Search

[Display omitted] • Non-antibiotic pharmaceuticals have higher risk than antibiotics in landfill leachates. • Population size contributed to the regional differences of pharmaceuticals in leachates. • Solid waste composition and loading affect pharmaceutical concentrations in leachate. • High level of pharmaceuticals was observed in the leachate of residual/food waste. Municipal solid waste (MSW) landfill sites have been identified as a significant source of pharmaceuticals in the environment because unused or expired pharmaceuticals are discarded into MSW, which eventually percolate into leachates. However, the contamination of pharmaceuticals in landfill leachate in China is not comprehensively understood. Previous research into factors influencing pharmaceutical concentrations focused on a limited number and type of target pollutants or restricted study area. In the present study, 66 pharmaceuticals were analyzed (including 45 antibiotic and 21 non-antibiotic pharmaceuticals, also categorized as 59 prescription and 7 non-prescription pharmaceuticals) in leachate samples from landfill sites with various characteristics in different regions of China. The results indicated that non-antibiotic pollutants were present at significantly higher concentrations than antibiotic pollutants, with median concentrations of 1.74 μg/L and 527 ng/L, respectively. Non-antibiotic pollutants also presented a higher environmental risk than antibiotic pollutants, by 2 to 4 orders of magnitude, highlighting that non-antibiotic pharmaceuticals should not be overlooked during the assessment of landfill leachate. Pharmaceutical concentrations in landfill leachate samples exhibited regional differences; the population size served by the landfills was the dominant factor contributing to the observed differences. In addition, landfill characteristics such as the solid waste composition and MSW loading can also affect pharmaceutical concentrations in landfill leachate. Despite the implementation of the classification and disposal policy of MSW in Shanghai, China since July 2019, specifying that unused or expired pharmaceuticals should be discarded as hazardous waste, high levels of pharmaceutical contaminations were detected in leachate from the main components of classified MSW (i.e., residual and food waste). These findings emphasize the importance of pharmaceutical management in solid waste systems. [ABSTRACT FROM AUTHOR]

l‐cysteine‐modified Fe3O4 nanoparticles (l‐cys@nFe3O4) were synthesized successfully and used as catalyst to activate persulfate (PS) for benzene, toluene, ethylbenzene, and xylenes (BTEX) degradation. The composite was fully characterized, and the l‐cys@nFe3O4 had more protrusions and l‐cys was combined on the surface of nFe3O4. The removals of BTEX were 78.2%, 85.1%, 85.3%, 81.2%, respectively, in PS/l‐cys@nFe3O4 system, while only 52.7% 57.8%, 60.8%, and 56.3% of BTEX removals reached under the same condition for nFe3O4 chelated with l‐cys in 48 h. Four successive cycles of BTEX degradation were completed in PS/l‐cys@nFe3O4 system. The synergistic mechanisms of BTEX degradation in PS/l‐cys@nFe3O4 system were investigated by electron paramagnetic resonance (EPR), benzoic acid (BA) probe and X‐ray photoelectron spectroscopy (XPS) tests. SFe bond in l‐cys‐Fe complexes promoted the electron transfer between nFe3O4 core and the solution, iron and iron at the interface, thereby promoting the Fe3+/Fe2+ cycle and the catalytic capacity of nFe3O4. The optimal pH of PS/l‐cys@nFe3O4 system was 3, while HCO3− and Cl− exhibited negative influences on BTEX degradation. Only 14.2%, 15.5%, 15.9%, and 15.6% BTEX had been removed in the presence of 0.12‐M PS and 8.0 g/L l‐cys@nFe3O4 under the actual groundwater condition. However, expanding the dosage of PS and l‐cys@nFe3O4 was an effective strategy to overcome the adverse effect. Practitioner Points: L‐cys@nFe3O4 were synthesized successfully and used as catalyst to activate PS for BTEX degradation.Four successive cycles of BTEX degradation were completed in PS/L‐cys@nFe3O4 system.lS―Fe bond in L‐cys@nFe3O4 promoted the electron transfer between PS and nFe3O4 core. [ABSTRACT FROM AUTHOR]

• nCaO 2 performed better for TCE degradation than conventional CaO 2. • Citric acid significantly enhanced TCE degradation. • HO was the primary ROSs in CaO 2 /Fe(II) and CaO 2 /Fe(II)–CA systems. • Cl− and HCO 3 − inhibited TCE degradation at different levels. • Effective degradation of TCE in actual groundwater was achieved. In this study, nCaO 2 was synthesized successfully and applied in the Fe(II)-based catalytic environments in investigating trichloroethylene (TCE) removal performance. nCaO 2 with the particle sizes in the range of 50–200 nm was prepared, and it performed better for TCE removal when compared to the conventional CaO 2. Further experimental results showed that 70.4% of TCE could be removed in 180 min at the nCaO 2 /Fe(II)/TCE molar ratio of 1/2/1, while this data was elevated to 86.1% in the presence of citric acid (CA) at the nCaO 2 /Fe(II)/CA/TCE molar ratio of 1/2/2/1 in the same test period. Probe compound tests, specifically designed for free radicals confirmation, demonstrated the presence of HO and O 2 − . Moreover, scavenging tests indicated that HO was the major radical responsible for TCE degradation but O 2 − promoted the removal of TCE in both nCaO 2 /Fe(II) and nCaO 2 /Fe(II)-CA system. In addition, the effects of initial solution pH and anions (Cl−, HCO 3 −) were also evaluated. The performance of TCE degradation in actual groundwater demonstrated that both nCaO 2 /Fe(II) and nCaO 2 /Fe(II)-CA systems can be applicable for TCE removal in ISCO practice and the nCaO 2 /Fe(II)-CA system is much promising technique. These fundamental data strongly confirmed the feasibility and potential of nCaO 2 based technique in the remediation of TCE contaminated groundwater. [ABSTRACT FROM AUTHOR]

In this study, 90.9% fluoranthene (FLT) was degraded in sodium percarbonate (2Na 2 CO 3 ·3H 2 O 2 , SPC) oxidation system by Fe(II) combined with sulfidated nano zero valent iron (S-nZVI) activation within 60 min in aqueous solution. Scavenging experiments and electron paramagnetic resonance detection suggested that HO•, O 2 −•, and 1O 2 contributed to the removal of FLT in SPC/Fe(II)/S-nZVI system. Based on the FLT degradation intermediates that were analyzed by GC-MS in SPC/Fe(II)/S-nZVI process, three potential FLT degradation pathways were speculated. The removal efficiency of FLT was inhibited with the presence of humic acid (HA) unless the concentration of HA was controlled at 1.0 mg L−1, and the presence of 1.0 mg L−1 HA favored the generation of HO•. The excellent removal performance of FLT (88.6%) could be achieved in actual groundwater by increasing the chemical dosages and adjusting the initial solution pH to acid environment. In soil slurry tests, the optimal reaction time and soil/water ratio were obtained as 24 h and 2/10, respectively, and the desired FLT degradation performances were obtained at pH 3 and 5 with the soil/water ratio of 2/10. This work effectively demonstrates the application potential of SPC/Fe(II)/S-nZVI system for the remediation of PAHs contamination in actual industrial sites. [Display omitted] • The mechanisms of FLT removal in aqueous solution were investigated. • HO• was the primary ROS in SPC/Fe(II)/S-nZVI system. • Three degradation pathways of FLT were proposed. • The effect of HA on FLT removal in aqueous solution was explored. • The optimal condition for FLT degradation in soil slurry system reaction time, soil/water, and pH were was clarified. [ABSTRACT FROM AUTHOR]

The use of zinc dioxide (ZnO2) powder as a source of H2O2 in a modified Fenton reaction catalyzed with Fe(II) to destroy trichloroethylene (TCE) was investigated. The experimental results showed that the optimum molar ratio of ZnO2/Fe(II)/TCE in ZnO2/Fe(II)/TCE system was 20/20/1 with a TCE removal of up to 99.6%. TCE degradation was significantly inhibited by the low reaction temperature and influenced by the initial solution pH, in which ZnO2/Fe(II)/TCE system was suited for high temperature and low pH settings. Both Cl− and HCO3− anions showed a detrimental effect on TCE elimination with HCO3− being more significant. The addition of a high concentration (100 mg/L) of HA in solution inhabited TCE degradation performance, while the effect was negligible at low concentrations (1–10 mg/L). The tests with hydroxyl radical (HO·) scavengers elucidated that TCE was mainly degraded by HO· radicals in ZnO2/Fe(II)/TCE system. TCE degradation and the dechlorination proceeded simultaneously, but the final release of Cl− was less than the degraded TCE, indicating the occurrence of chlorinated intermediates in the reaction process. [ABSTRACT FROM AUTHOR]

The degradation performance of trichloroethylene (TCE) by sodium percarbonate (SPC) activated with citric acid (CA) chelated Fe(II) in the presence of nonionic surfactant Tween-80 was investigated. The addition of CA successfully prevented the precipitation of iron and facilitated TCE degradation. However, Tween-80 had an inhibitory effect on TCE degradation mainly due to the competition of ∗OH between Tween-80 and TCE. The effect of SPC and Fe(II) dosage on TCE degradation was also explored and the results displayed that 87.2% of TCE could be degraded in 15 min at the SPC/Fe(II)/CA/TCE molar ratio of 3/4/2/1. Free radical probe tests confirmed that both O2−∗ and ∗OH were generated in the SPC/Fe(II)/CA system. Free radical scavenging tests implied that the degradation of TCE in the SPC/Fe(II)/CA system was mainly attributed to ∗OH, while O2−∗ was only partially involved in the degradation of TCE. In addition, TCE removal was suppressed with the raising of the initial solution pH from 3.0 to 9.0. The actual groundwater (containing Tween-80) tests confirmed that 93.2% of TCE degradation could be achieved at the SPC/Fe(II)/CA/TCE molar ratio of 30/40/10/1 and strongly demonstrated that the SPC/Fe(II)/CA process has potential for the in situ treatment of TCE contaminated groundwater in the presence of surfactant Tween-80. In conclusion, TCE degradation by Fe(II) activated SPC system in the presence of Tween-80 can be significantly enhanced with the addition of CA, and this finding offers an innovative direction for removing chlorinated organic contaminants from groundwater in contaminated site after surfactant solubilization treatment. Image 1 • SPC/Fe(II)/CA process was applied to remove TCE in the presence of Tween-80. • The addition of CA facilitated TCE degradation in SPC/Fe(II) system. • TCE removal was mainly attributed to. OH, while O 2 − also partially involved. • TCE degradation in actual groundwater was successfully achieved. [ABSTRACT FROM AUTHOR]

In this study, nano‐CaO2 (nCaO2) was successfully synthesized and constituted the nCaO2/Fe(II) system applying to remediate BTEX, which are typical mixed pollutants in contaminated groundwater. The particle size of the synthesized nCaO2 was 108.91 nm, and it displayed better BTEX remediation performance than that of commercial CaO2. The innovative generation pattern of hydroxyl radicals (HO·) in the nCaO2/Fe(II) system has been investigated using benzoic acid as the HO· probe, and the proper molar ratio of nCaO2/Fe(II) was optimized as 1/1. Over 90% of BTEX was removed in 180 min with the nCaO2/Fe(II)/BTEX molar ratio of 40/40/1. Further experiments evaluated the influence of co‐existence of mixed pollutants chlorinated hydrocarbon compounds (CHCs) or surfactant constituents on BTEX remediation performance. The experimental results suggested that CHCs have limited influence on BTEX removal rate and surfactants have negative effects on BTEX remediation performance in the experimental conditions. In conclusion, the findings in this study could give some inspirations to apply the nCaO2/Fe(II) process in remediating co‐existing pollutants in contaminated groundwater. Practitioner points: nCaO2/Fe(II) system applied to remediate mixed contaminants.HO· generation pattern of the nCaO2/Fe(II) system has been investigated.The influence of chloride hydrocarbon compounds have been studied.The effects of surfactants were evaluated. [ABSTRACT FROM AUTHOR]

Highlights • CT degradation in CaO 2 /Fe(II) system is promoted by MeOH addition. • The leading species for CT degradation are O 2 −, CO 2 −. • CHCl 3 , C 2 Cl 4 , and C 2 Cl 6 were the intermediates of CT. • A reduction mechanism for CT degradation was proposed. • Efficient removal of CT in groundwater was attained. Abstract This study investigated the reductive initiation for the depletion of highly oxidized/perhalogenated pollutants, specifically the degradation of carbon tetrachloride (CT) was induced by adding methanol (MeOH) into a ferrous ion (Fe(II)) activated calcium peroxide (CaO 2) system. The results indicated that CT could be completely degraded within 20 min at CaO 2 /Fe(II)/MeOH/CT molar ratio of 30/40/10/1 in this system. Scavenging tests suggested that both superoxide radical anion (O 2 −) and carbon dioxide radical anion (CO 2 −) were predominant reactive species responsible for CT destruction. Hydroxymethyl radicals (CH 2 OH), an intermediate in the transformation of MeOH, could also initiate CT degradation by reducing C Cl bond. GC/MS analysis identified CHCl 3 , C 2 Cl 4 , and C 2 Cl 6 as the intermediates accompanied by CT destruction, and a reduction mechanism for CT degradation was proposed accordingly. In addition, the impact of solution matrix and initial solution pH were evaluated, and the results showed that Cl−, NO 3 −, and HCO 3 − had adverse effects on CT degradation. Moreover, the alkaline condition was unfavorable to CT depletion. In conclusion, the results obtained in the actual groundwater tests encouragingly demonstrated that the CaO 2 /Fe(II)/MeOH process is a highly promising technique for the remediation of CT-contaminated groundwater. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • FA and CIT can enhance Fe(II)/CP process for chlorinated hydrocarbons removal. • HO and CO2− radicals were proved to be co-existed in the process by EPR tests. • CO2− were responsible for CT dechlorination and HO for PCE and TCE degradation. • Effective degradation of CT, PCE and TCE was achieved in actual groundwater. Abstract Two carboxylic acids (formic acid (FA) and citric acid (CIT)) enhanced the Fenton process using Fe(II)-activated calcium peroxide (CP) to develop a hydroxyl (HO) and carbon dioxide radical (CO 2 −) coexistence process for the simultaneous redox-based degradation of three chlorinated hydrocarbons (CHs), namely carbon tetrachloride (CT), tetrachloroethene (PCE), and trichloroethene (TCE), was investigated. The experimental results showed that CT removal was increased while PCE and TCE degradation were decreased with the addition of FA to the Fe(II)/CP system. However, addition of CIT to the Fe(II)/CP/FA system enhanced the removal efficiency of all three contaminants. For example, 81.7%, 79.4%, and 96.1% of CT, PCE, and TCE, respectively, were removed simultaneously under the optimal molar ratio of 12/12/12/12/1 of CIT/CP/Fe(II)/FA/CHs. Mechanism study confirmed the specific roles of HO and secondarily generated CO 2 − radical. PCE and TCE were degraded oxidatively by HO while CT was degraded via reductive dechlorination by CO 2 −. Carbonate reduced PCE and TCE degradation in actual groundwater as it consumed reactive oxygen species, whereas humic acid and neutral pH had minimal impact on contaminant removal. These results can help us better understand the synergistic effects of carboxylic acids in the modified Fenton process for the redox degradation of refractory chlorinated hydrocarbons. [ABSTRACT FROM AUTHOR]

Abstract The surface properties of nanocomposites are influenced by the existence of inorganic species that may affect its performance for specific catalytic applications. The impact of different ionic species on particular catalytic activity had not been investigated to date. In this study, the surface charge (zeta potential) of graphene-oxide-supported nano zero valent iron (G-nZVI) was tested in definitive cationic (Na+, K+, Ca2+ and Mg2+) and anionic (Br−, Cl−, NO 3 −, SO 4 2−, and HCO 3 −) environments. The efficiency of G-nZVI catalyst was inspected by measuring the generation of reactive oxygen species (ROS) for the degradation of 1,1,1-trichloroethane (TCA) in sodium percarbonate (SPC) system. Tests conducted using probe compounds confirmed the generation of OH and O 2 − radicals in the system. In addition, the experiments performed using scavenging agents certified that O 2 − were primary radicals responsible for TCA removal, along with prominent contribution from OH radicals. The study confirmed that G-nZVI catalytic capability for TCA degradation is notably affected by various cationic species. The presence of Ni2+ and Cu2+ significantly enhanced (94%), whereas Na+ and K+ had minor effects on TCA removal. Overall, the results indicated that groundwater ionic composition may have low impact on the effectiveness of G-nZVI-catalyzed peroxide TCA treatment. Graphical abstract Unlabelled Image Highlights • Dominant groundwater cations effect the performance efficiency for degradation • Surface charge and organic ions effect investigated for the degradation of TCA a persistent contaminant in hydrosphere. • Generation of reactive oxygen species for remediation of TCA in percarbonate system • The ionic composition of groundwater has a relatively minor effect on TCA removal for the G-nZVI catalyzed system. [ABSTRACT FROM AUTHOR]

Fe(II) activated sodium percarbonate (SPC) process (SPC/Fe(II)) could efficiently remove sulfamethoxazole (SMX) in the aqueous phase, and has the potential in groundwater remediation. However, the degradation mechanisms, especially the degradation products and pathways till now have remained unclear. In the present study, intermediate products were identified using high resolution liquid chromatography coupled with ion trap and time-of-flight mass spectrometry (LCMS-IT-TOF). Nine intermediate products were identified, six of which have not yet been reported during the oxidation of SMX. The oxidation mechanisms involved hydroxyl substitution, the cleavage of sulfonamide bond, isoxazole ring opening and a rearrangement following the loss of the SO 2 -group. Based on the identified intermediate products, the degradation pathways of SMX by SPC/Fe(II) process were illustrated. Fenton's reaction after the dissolution of SPC was proposed as the main reaction mechanisms, which was checked and confirmed by radical species detection tests and radical species scavenging studies. The results showed that although both O 2 − and HO were present in SPC/Fe(II) system, HO was dominant in the system while O 2 − was seldom involved in the degradation of SMX. These findings provided useful information and supported the application of this advanced oxidation process for antibiotics elimination in the groundwater. [ABSTRACT FROM AUTHOR]

The degradation of carbon tetrachloride (CT) by Fe(II) activated calcium peroxide (CaO 2 ) in the presence of ethanol (CH 3 CH 2 OH, EtOH) was investigated. The results showed that CT could be completely degraded in 20 min with 3.90 mmol L −1 CaO 2 , 5.20 mmol L −1 Fe(II) and 1.30 mmol L −1 EtOH in CaO 2 /Fe(II)/EtOH system. Superoxide radical anion (O 2 •− ) and hydroxyethyl radical ( • CHCH 3 OH, HER) were demonstrated as the main radicals for CT degradation which were confirmed by scavenging tests and electron paramagnetic resonance (EPR) detection. The mechanism of CT degradation was mainly due to the split of C–Cl and CT degradation pathway was proposed accordingly. Further investigation suggested that the solution pH in range of 3–5 were favorable to CT degradation. Both Cl − and HCO 3 − had inhibitive effect on CT removal, while the influence of NO 3 − and SO 4 2− could be negligible. Moreover, the results of experiments performed using actual groundwater demonstrated that an adverse impact occurred on CT degradation, but this drawback could be overcome by increasing reagent dosages. In summary, CT degradation in Fe(II) activated CaO 2 system can be significantly promoted by EtOH addition, and this finding, for the first time, provides an innovative technology for degradation of the highly oxidized organic contaminants. [ABSTRACT FROM AUTHOR]

Highlights • PPCPs in a typical urban river of megacity Shanghai were investigated. • Untreated wastewater was proposed as a major source of PPCPs in Huangpu River. • Higher concentrations of PPCPs were detected in the lower reach and dry seasons. • Overflow of untreated wastewater led to higher PPCPs load after rainfall. Abstract Occurrence of eleven pharmaceuticals and personal care products (PPCPs) along Huangpu River, a representative urban river of megacity Shanghai, was investigated in four sampling campaigns. The overall concentrations of PPCPs ranged from

[Display omitted] • The presence of TW-80 improved the reductive degradation of CT in PS oxidation system. • The strengthening effect of CA or nZVI on CT removal in PS/Fe(II) system was confirmed. • Both the secondary surfactant radicals (R•CHOH) and O 2 −• were responsible for CT removal. • Efficient degradation of mixed TCE, PCE, and CT was achieved with TW-80 presence in both PS/Fe(II)/CA and PS/Fe(II)/nZVI systems. Despite the wide range of applications for persulfate-based advanced oxidation processes (PS-based AOPs) in groundwater remediation, the elimination of perchlorinated hydrocarbon contaminants such as carbon tetrachloride (CT) remains a challenge. In this research, we discovered that CT degradation in PS/Fe(II) system was greatly promoted with the presence of surfactant Tween-80 (TW-80), whereas it was hardly removed without TW-80 presence. The introduction of citric acid (CA) or nano zero-valent iron (nZVI) could both enhance the efficacy of PS/Fe(II) system. Through scavenging experiments and electron paramagnetic resonance analysis, the generated secondary surfactant radicals (R•CHOH) from TW-80 and superoxide radicals (O 2 −•) were identified as the driving factors behind CT degradation. CT dechlorination reached 70.6% and 71.8% in PS/Fe(II)/CA and PS/Fe(II)/nZVI systems, respectively, and the potential degradation routes of CT were offered. Additionally, the effect of TW-80 concentration and solution matrixes (solution pH and inorganic ions) on CT degradation was assessed. Furthermore, the removal of mixed chlorinated hydrocarbon contaminants and actual groundwater tests were also performed. Given that surfactants are commonly used in soil and groundwater remediation, this research provides a new prospect and theoretical support for the treatment of perchlorinated contaminants in groundwater with the presence of surfactants. [ABSTRACT FROM AUTHOR]

Surfactant-enhanced in-situ chemical oxidation (S-ISCO) is widely applied in soil and groundwater remediation. However, the role of surfactants in the reactive species (RSs) transformation remains inadequately explored. This work introduced nonionic surfactant Tween-80 (TW-80) into a nano zero-valent iron (nZVI) activated persulfate (PS) system. The findings indicate that PS/nZVI/TW-80 system can realize the concurrent removal of trichloroethylene (TCE), tetrachloroethene (PCE), and carbon tetrachloride (CT), whereas CT cannot be eliminated without TW-80 presence. Further analysis unveiled that hydroxyl (HO•) and sulfate radicals (SO 4 －•) were the primary species for TCE and PCE degradation, while CT was reductively eliminated by surfactant radicals generated from TW-80. Moreover, the surfactant radicals were found to accelerate Fe(III)/Fe(II) cycle, reduce the production of iron sludge, and increase PS decomposition. The possible degradation routes of mixed chlorinated hydrocarbons (CHCs) and the decomposition pathways of TW-80 were proposed through the density function theory (DFT) calculation and intermediates analysis. Additionally, the effects of other nonionic surfactants on the simultaneous removal of TCE, PCE, and CT, and the practical applications using the actual contaminated groundwater were also evaluated. This study provides theoretical support for the simultaneous removal of CHCs, particularly those containing perchlorinated contaminants, using the S-ISCO techniques. [Display omitted] • Simultaneous removal of CHCs (TCE, PCE, and CT) was achieved with TW-80 presence. • TCE and PCE were degraded by HO• and SO 4 －•, while CT was reductively eliminated by surfactant radicals. • The accelerated Fe(III)/Fe(II) cycle by the surfactant radicals was confirmed. • Possible degradation pathways of CHCs and TW-80 decomposition routes were proposed. [ABSTRACT FROM AUTHOR]

In this study, the removal performance and degradation mechanisms of fluoranthene (FLT) in sodium percarbonate (SPC) activated by Fe(II) system were investigated, in which 97.5% removal of FLT could be achieved within 15 min when the concentrations of SPC and Fe(II) were 0.03 and 0.2 mM, respectively. The presence of HO·, O2−· and 1O2 was demonstrated by probe tests and electron paramagnetic resonance (EPR) detections, and scavenging experiments further proved that the leading reactive oxygen species (ROSs) contributed to FLT removal in SPC/Fe(II) system was HO·. The p-hydroxybenzoic acid analytical result (the reaction product between benzoic acid and HO·) found that 66.5% of HO· in the system was produced in the first 5 min of the reaction. Several intermediates of FLT were detected by GC–MS and three probable FLT degradation pathways were proposed. The effect of SPC dosage, Fe(II) concentration, initial solution pH and inorganic anions (Cl− and HCO3−) on FLT degradation were assessed. 90.3% FLT was removed in actual groundwater when the dosages of SPC and Fe(II) were 0.15 and 1.0 mM, respectively. This result indicated that FLT removal could be improved by elevating the dosages of SPC and Fe(II) and adjusting the initial solution pH to 5.0, confirming the effective removal of FLT in actual groundwater in SPC/Fe(II) system. Overall, this study demonstrated that SPC/Fe(II) system has broad prospective in the remediation of FLT-contaminated groundwater. [ABSTRACT FROM AUTHOR]

Few researches have focused on the role of nanoscale zero‐valent iron (nZVI) in Fenton‐like process for polycyclic aromatic hydrocarbons (PAHs) removal. In this study, the naphthalene (NAP) degradation tests in ultrapure water showed that nZVI addition could enhance NAP degradation from 79.7% to 99.0% in hydrogen peroxide (H2O2)/Fe (II)/nZVI/NAP system at the molar ratio of 10/5/3/1, showing the excellent role of nZVI in promoting NAP removal. Multiple linear regression analysis found that the correlation coefficient between H2O2 consumption and NAP degradation was converted from −9.17 to 0.48 with nZVI and 1‐mM H2O2, indicating that nZVI could decompose H2O2 more beneficially for NAP degradation. Multiple Fe (II)‐dosing and iron leaching tests revealed that nZVI could gently liberate Fe (II) and promote Fe (II)/Fe (III) redox cycle to enhance the NAP degradation. When the H2O2/Fe (II)/nZVI/NAP molar ratios of 10/5/3/1 and 50/25/15/1 were applied in the simulated NAP contaminated actual groundwater and soil slurry, respectively, 75.0% and 82.9% of NAP removals were achieved. Based on the major degradation intermediates detected by GC/MS, such as 1,4‐naphthalenedione, cinnamaldehyde, and o‐phthalaldehyde, three possible NAP degradation pathways were proposed. This study provided the applicable potential of nZVI in Fenton process for PAHs contaminated groundwater and soil remediation. Practitioner Points: nZVI enhanced the NAP degradation in Fenton‐like process.Three schemes of NAP degradation pathway were proposed.nZVI performed well in the remediation of the simulated NAP contamination. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fe 3 S 4 was synthesized and used for the enhancement of advanced oxidation systems. • The enhanced mechanisms on the surface of Fe 3 S 4 were elucidated. • The existing reactive species and their contributions were evaluated. • The degradation pathways and the toxicities of intermediates were investigated. In this research, greigite (Fe 3 S 4) was innovatively applied for the enhancement of PDS/Fe(II) system. From XRD and SEM analyses, Fe 3 S 4 was successfully synthesized and appeared uniform sphere-like particles with a petal-like structure. Trichloroethylene (TCE), as the target, was significantly degraded from 28.5 % to 92.8 % in PDS/Fe(II)/Fe 3 S 4 system. The enhanced mechanisms, differences, and superiority of Fe 3 S 4 against the other three iron sulfides were elucidated as follows: (1) on account of the abundant reduction sites on its surface, Fe 3 S 4 could not only directly release Fe(II) and accelerate Fe(II) regeneration by sulfur substances, but also participate in the process of O 2 −• generation, and (2) the reaction mainly took place on Fe 3 S 4 surface, in which the surface-bound reactive species (RSs) were of great importance for TCE degradation. Through EPR, quantification, and scavenging tests of RSs, HO•, SO 4 −•, and O 2 −• were all the dominant RSs responsible for TCE removal. Besides, these enhanced systems had high tolerance on complex water conditions and could remediate various contaminants in actual groundwater. Three TCE degradation pathways were deduced in four iron sulfide-enhanced systems and the toxicities of intermediates were evaluated, recommending that Fe 3 S 4 -enhanced system was of the least toxicity and most favorable for application in practice. [ABSTRACT FROM AUTHOR]

[Display omitted] • ZVI and B-assisted nCP/Fe(III) systems could achieve efficient decontamination. • The dominant active species in the enhanced nCP/Fe(III) systems were identified. • Fe(II) was generated simultaneously by Fe(III) reduction and ZVI corrosion. • B continuously supplied electrons to Fe(III) to ensure fast Fe(II) generation. • Efficient NAP degradation in various water matrixes was achieved. Nano calcium peroxide (nCP) has attracted attention as an alternative for liquid H 2 O 2 -mediated advanced oxidation processes. However, the slow reduction kinetics of Fe(III) still significantly limit its application. Here, zero valent iron (ZVI) and amorphous boron (B) could remarkably promote the Fe(III)/Fe(II) cycle in nCP/Fe(III) system to generate various active species (HO•, O 2 −•, and 1O 2) with HO• acting as the predominant role in naphthalene (NAP) degradation. nCP/Fe(III)/ZVI process could achieve 98.2% NAP degradation and 70.6% TOC removal, compared with 97.5% NAP degradation and 56.3% TOC removal in nCP/Fe(III)/B process. ZVI could donate electrons to Fe(III) to generate Fe(II) and itself could also be corroded to release Fe(II). B was stepwise oxidized (B0 to B(I)/B(II) to B 2 O 3) and continuously supplied electrons to Fe(III) to ensure fast and long-lasting Fe(II) generation. Moreover, B 2 O 3 was dissolved as H 3 BO 3 in aqueous solution, which kept the B surface reactive for the continuous reduction of Fe(III). Although the two co-activators showed different promotion mechanisms in nCP/Fe(III) system, both systems exhibited excellent NAP degradation performance in different experimental conditions and various water matrixes. Overall, this study provided the strategies to overcome the limitation of nCP/Fe(III) system and extended its application potential in contaminants remediation. [ABSTRACT FROM AUTHOR]

• PFASs in different MSW disposal sites worldwide are summarized and compared. • Ultrashort-chain PFASs showed unexpectedly high concentration levels in leachate. • Levels of PFASs in incineration ash were lower than that in incineration leachate. • Application of composts led to the release of PFASs back into the soil-crop system. • Non-specific methods and non-target analysis are promising for PFAS identification. Per- and polyfluoroalkyl substances (PFASs) have become a crucial environmental concern owing to their exceptional persistence, ability to bioaccumulate within ecosystems, and potential to adversely affect biota. Products and materials containing PFASs are usually discarded into municipal solid waste (MSW) at the end of their life cycle, and the fate of PFASs may differ when different disposal methods of MSWs are employed. To date, limited research has focus on the occurrence, behaviors, and fate of PFASs emitted from various MSW disposal sites. This knowledge gap may lead to an underestimation of the contribution of MSW disposal sites as a source of PFASs in the environment. In this review, we collated publications concerning PFASs from typical MSW disposal sites (i.e., landfills, incineration plants, and composting facilities) and explored the occurrence patterns and behaviors of PFASs across various media (e.g., landfill leachate/ambient air, incineration plant leachate/ash, and compost products) in these typical MSW disposal sites. In particular, this review highlighted ultrashort-chain perfluoroalkyl acids and "unknown"/emerging PFASs. Additionally, it meticulously elucidated the use of non-specific techniques and non-target analysis for screening and identifying these overlooked PFASs. Furthermore, the composition profiles, mass loads, and ecological risks of PFASs were compared across the three typical disposal methods. To the best of our knowledge, this is the first review regarding the occurrence, behaviors, and fate of PFASs in typical MSW disposal sites on a global scale, which can help shed light on the potential environmental impacts of PFASs harbored in MSWs and guide future waste management practices. [Display omitted] [ABSTRACT FROM AUTHOR]

Nano zero-valent (nZVI) based composite have been widely utilized in environmental remediation. However, the rapid agglomeration and quick deactivation of nZVI limited its application on large scale. In this work, CaCO 3 supported nZVI-Ni catalyst, namely nZVI-Ni@CaCO 3 was prepared and used for the efficient removal of trichloroethylene (TCE) in PS oxidation process. The successful disbursement of nZVI-Ni on CaCO 3 support material not only increased the surface area of nZVI-Ni@CaCO 3 (69.45 m2/g) with respect to CaCO 3 (5.92 m2/g) and bare nZVI (13.29 m2/g) but also improved the catalytic activity. XRD, XPS and FTIR analysis confirmed the successful formation of nZVI-Ni@CaCO 3 nanoparticles. The nZVI-Ni@CaCO 3 nanoparticles combined with PS had achieved complete removal of TCE (99.8%) with dosage of 36 mg/L and 1.34 mM respectively. These results showed that the use of CaCO 3 as support material for nZVI-Ni could have significant influence on contaminant removal process. Scavenging and EPR tests validated the existence of SO 4 •–, OH• and O 2 •– radicals in PS/nZVI-Ni@CaCO 3 system and highlighted the dominant role of SO 4 •– radicals in TCE removal process. HCO 3 ˉ ions and humic acid have shown adverse effect on TCE removal due to radical scavenging and buffering effect. Owing to improved catalytic activity and easy preparation, the nZVI-Ni@CaCO 3 nanoparticles could be served as an alternative strategy for environmental remediation. [Display omitted] • Incorporation of Ni and CaCO 3 has significantly alleviated the passivation problem of nZVI. • About 99.9% TCE removal was achieved in PS/nZVI-Ni@CaCO 3 system after 1 h. • PS/nZVI-Ni@CaCO 3 system has showed excellent TCE removal in weak alkaline pH. • HCO 3 ˉ showed more adverse effect on TCE removal in comparison to Clˉ. • SO 4.•– played dominant role in TCE removal in PS/nZVI-Ni@CaCO 3 system. [ABSTRACT FROM AUTHOR]

[Display omitted] • Over 90% NAP could be removed in PDS/Fe(II)/CaSO 3 and PMS/Fe(II)/CaSO 3 systems. • The enhancement mechanism of CaSO 3 on the removal of NAP was illuminated. • SO 4 − was the dominant ROS for NAP degradation in CaSO 3 -enhanced systems. • NAP degradation intermediates and pathways were elucidated. • The applicability of CaSO 3 -enhanced systems in various water matrixes was assessed. Na 2 SO 3 and NaHSO 3 have been widely used as the source of SO 3 2− to participate in the reproduction of Fe(II) in iron-based advanced oxidation processes. In this work, CaSO 3 with low solubility was innovatively introduced and compared with Na 2 SO 3 and NaHSO 3 to investigate their effects on naphthalene (NAP) degradation in Fe(II)-activated peroxydisulfate (PDS) and peroxymonosulfate (PMS) processes. The results showed that CaSO 3 displayed a better performance due to its sustained-release of SO 3 2−, and NAP removal increased from 57.6% and 77.7% to 91.4% and 98.5% in PDS/Fe(II) and PMS/Fe(II) processes, respectively, with the addition of CaSO 3. The enhancement mechanisms of CaSO 3 were illustrated by measuring the variation of iron and SO 3 2− concentrations and by quantitatively determining the production of reactive oxygen species (ROS). The dominant ROS generated in CaSO 3 -enhanced systems was confirmed by scavenging tests. Moreover, NAP degradation intermediates and pathways, as well as the toxicological properties of intermediates, were accordingly elucidated. Finally, CaSO 3 -enhanced systems had a wide application range of pH, and exhibited a great performance on the tolerance of various water matrixes. The significant removal of various contaminants in CaSO 3 -enhanced processes confirmed that these techniques are suitable for the remediation of organic contaminated groundwater. [ABSTRACT FROM AUTHOR]

[Display omitted] • The degradation kinetics and mechanisms of OH with FF were systematically studied. • The k of OH with FF was corrected to be 1.96 × 109 M−1 s−1 by LFP experiment. • HAA reaction of chiral carbons was the most favorable initial pathway for OH. • Chlorine moiety was resistant to be destroyed during initial oxidation process. Antibiotic residues in aquatic environments can be effectively degraded by hydroxyl radical (OH)-based advanced oxidation processes (AOPs). However, the reaction kinetics and mechanisms have not been comprehensive determined due to the limitations of conventional competition kinetic methods and mass spectrometry-based product identification, as these methods fail to exclude interference from secondary radicals and are unable to capture unstable intermediates or transient species. In this study, these limitations were overcome using laser flash photolysis (LFP) and density functional theory (DFT) calculations, allowing accurate determination of the OH-initiated reaction kinetics and degradation mechanisms of florfenicol (FF), a model veterinary antibiotic compound that is frequently detected in the environment. Based on the LFP experiment results, the second order rate constant (k) between OH and FF was determined to be 1.96 × 109 M−1 s−1 by tracking the typical signal of (SCN) 2 −. Furthermore, DFT calculations revealed two distinct mechanisms for OH addition to the benzene ring and identified hydrogen atom abstraction (HAA) reaction from chiral carbons as being the most favorable initial reaction for OH. In addition, the destruction of chlorine moiety occurred via hydroxylation-chlorine abstraction, rather than direct chlorine abstraction or substitution reactions. The resistance of chlorine moiety to degradation during the initial oxidation process, resulted in the formation of chlorine-containing by-products. This study provided a novel approach to comprehensively investigate the mechanisms of emerging contaminants elimination during OH-based AOPs. [ABSTRACT FROM AUTHOR]

[Display omitted] • The removal performance of various types of CHCs was systematically examined. • The predominant reactive species were identified in different enhanced systems. • The removal efficiencies, costs, and toxicity of the enhancers were evaluated. • The most applicable techniques for the single CHC were elucidated. • A complete set of remediation strategies for multiple mixed CHCs were formed. Conventional Fe(II)-based advanced oxidation processes required enhancement to achieve desired contaminant removal. In this study, the introduced enhancers were divided into four categories: organic acids-based enhancers, inorganic reductants, slow-release iron substances, and short-chain alcohols or acids. Chlorinated hydrocarbons (CHCs) were chosen as the targets and classified into three groups: chlorinated olefins, non-perchlorinated alkanes, and perchlorinated alkanes. The remediation effects of different enhanced systems (oxidant/Fe(II)/enhancer) on different types of CHCs were systematically examined. The predominant reactive species were identified and elucidated to provide the most applicable technique for the remediation of each type of chlorinated hydrocarbon. Their dechlorination and mineralization degree were investigated as well. Meanwhile, a complete set of remediation strategies for multiple mixed CHCs in contaminated groundwater were formed by combining the remediation efficiencies, costs, and toxicity of the enhancers, which could provide far-reaching implications for the systemic governance of CHCs in practical applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • The mechanisms of FLT degradation by FeS 2 /SPC process were revealed. • HO•, CO 3 –•, O 2 –•, and 1O 2 were participated in FLT degradation. • Three degradation pathways of FLT were proposed. • The effects of various solution matrixes on FLT removal were explored. • The effects of surfactants and organic acids on FLT solubilization from soil were investigated. Sodium percarbonate (SPC) induced advanced oxidation processes have been used for the remediation of polycyclic aromatic hydrocarbons (PAHs) contamination, however, the feasibility studies of SPC and pyrite (FeS 2) process are scarce. In this work, FeS 2 served as a catalyst and reductant to activate SPC for fluoranthene (FLT) removal. 100% FLT removal was obtained at an initial solution pH of 5.90 with FeS 2 and SPC dosages of 0.5 g/L and 0.02 mM, respectively, and the influences of initial aqueous solution pH, dissolved oxygen, and various aqueous solution matrixes on FLT degradation were explored. Based on the results of electron paramagnetic resonance detection and scavenging experiments, it was demonstrated that HO•, 1O 2 , and O 2 −• played dominant roles in the removal of FLT, whereas CO 3 −• could only be involved in the ROS proliferative reaction in FeS 2 /SPC process due to the weak oxidizing capacity. Additionally, three FLT degradation pathways were proposed based on the detected degradation intermediates 1-phenylnaphthalene, indane, and phthalic acid. Finally, the desorption of FLT in soil was investigated by employing surfactants and organic acids, with organic acids being less effective than surfactants. Since the majority of organic acids can be utilized as advanced oxidation process promoters, their practical application is advantageous. [ABSTRACT FROM AUTHOR]

• nCP/FeS 2 /CA system could degrade over 90% NAP at a wide pH range of 3–9. • Reductive sulfur species and citric acid played a vital role in Fe(II) regeneration. • nCP/FeS 2 /CA system achieved over 90% of NAP removal in various water matrixes. • Mechanisms of NAP degradation in nCP/FeS 2 /CA system were explored in detail. • NAP degradation intermediates were successfully detoxified. In this research, pyrite was applied in synergy with citric acid for the activation of homemade nano-calcium peroxide to degrade naphthalene in aqueous solution. Results showed that over 90% of naphthalene could be removed within 180 min at a pH range of 3–9 due to the proton-releasing ability of pyrite. Hydroxyl radical, alkyl radical, and singlet oxygen were all detected by electron paramagnetic resonance spectra, with hydroxyl radical playing a dominant role in naphthalene degradation. The nano-calcium peroxide was mainly activated by Fe(II) leached from pyrite in homogeneous ways and the vital role of Fe(III) was also revealed. The superior naphthalene degradation in this system was attributed to the excellent electron-donating capacity of reductive sulfur species in Fe(II)/Fe(III) cycle and the increased concentration of available iron species by the chelating effect of citric acid. Meanwhile, the system showed high tolerance to complex water matrixes and excellent degradation performance for other polycyclic aromatic hydrocarbons and chlorinated olefins. In addition, the naphthalene degradation pathways and the toxicity of detected intermediates were investigated. This research revealed the mechanism of nano-calcium peroxide activation by pyrite coupled with citric acid and demonstrated the great application potential of this system in the treatment of polluted groundwater. [ABSTRACT FROM AUTHOR]

The performance of trichloroethylene (TCE) degradation by sodium percarbonate (SPC) activated with Fe(II) in the presence of 3.0 g/L sodium dodecyl sulfate (SDS) as well as the role of SDS in the SPC/Fe(II) system was investigated since SDS is a common surfactant used in groundwater remediation for improving TCE dissolution to the aqueous phase. The results showed that though the introduction of SDS could inhibit the TCE degradation, the inhibiting effect was less with the increasing SDS dose. In the presence of SDS, TCE could be completely removed with the SPC/Fe(II)/TCE molar ratio of 40/80/1. Experiments with free radical probe compounds and radical scavengers elucidated that TCE was mainly oxidized by both HO· and O2-·. A weakly acidic environment was more favorable to TCE degradation. Nevertheless, HCO3- at a high concentration had a strongly inhibitive effect on the TCE degradation but the influence of Cl− was negligible. Finally, the excellent TCE degradation achieved in actual groundwater demonstrated that Fe(II) activated SPC technique was applicable in the remediation of TCE contaminated groundwater in the presence of SDS. Practitioner points: The effects of SDS were evaluatedSPC/Fe(II)/SDS system applied to remediate TCEThe mechanism of HO· and O2-· generation had been investigatedCl− and HCO3- affected TCE degradation at different levelsThe performance of TCE removal in actual groundwater had been studied [ABSTRACT FROM AUTHOR]

A comprehensive characterisation of four phenolic compounds in surface water and various emission sources was conducted simultaneously in a typical industrial city upstream of the Taihu Lake watershed. The overall concentrations of the target compounds ranged from 0.15 to 2.75 μg/L in the surface water and from 0.43 to 377 μg/L in the emission sources. Relatively high concentration levels were observed in August, during which the rainy season typically occurred in the study area, indicating seasonal emission sources. The spatial distribution revealed severe phenolic-compound contamination in the northeast part of the study area. According to the relationships between the surface water and emission sources, combined-sewer overflow and surface runoff from agricultural activities were identified as seasonal emission sources that were responsible for the increased concentration levels in wet seasons. Indirect discharge of industrial wastewater was proposed as a persistent emission source responsible for the severe contamination level in the northeast region over the entire sampling period, accounting for 16.5% of the phenolic-compound load in a demonstration river section. The findings of this study are useful for identifying the sources of phenolic compounds and controlling the contamination from the main sources in a typical industrial city. Unlabelled Image • Phenolic compounds were studied in surface water and wastewater. • Relationships between surface water and emission sources were discussed. • CSOs and agricultural runoff were identified as two major seasonal sources. • Indirect discharge of industrial wastewater was proposed as a persistent source. [ABSTRACT FROM AUTHOR]

• FeS@nZVI-rGO catalyst was applied to activate SPS and PMS to remove TCE. • FeS@nZVI-rGO had better performance characteristics than nZVI-rGO for SPS and PMS systems. • Rapid oxidant decomposition and iron loss from FeS@nZVI-rGO were mitigated. • FeS@nZVI-rGO had wider pH application range in SPS and PMS systems. The performance of trichloroethene (TCE) removal was initially investigated in sodium persulfate (SPS) or potassium monopersulfate triple salt (PMS) oxidative environment by reduced graphene oxide (rGO) supported nZVI (nZVI-rGO) catalyst and further the role of sulphur by anchoring nano FeS on nZVI-rGO (FeS@nZVI-rGO) was evaluated. The high usage of oxidants and stability of FeS@nZVI-rGO catalyst were significantly improved due to the insoluble nature of this innovative catalyst by involvement of nano FeS which limited the rapid iron loss caused by the corrosion of active sites and mitigated rapid oxidants decomposition in FeS@nZVI-rGO/SPS and FeS@nZVI-rGO/PMS systems. The tests for target contaminant removal showed that over 95 % TCE could be removed at 100 mg L−1 FeS@nZVI-rGO and 1.2 mM SPS or 0.3 mM PMS dosages, in which over 85 % TCE could be dechlorinated. The reactive oxygen radicals (ROSs) generation mechanisms and their contribution to TCE removal were investigated through radical scavenge tests in both systems, indicating that both HO and SO 4 − were the major ROSs rather than O 2 −. In conclusion, this study revealed the well function and fundamental mechanism of this innovative catalyst by anchoring nano FeS and worth of further demonstration of this technique in TCE contaminated groundwater remediation application. [ABSTRACT FROM AUTHOR]

• nZVI-Ni bimetallic composite showed better properties in activating SPS for TCE degradation in the presence of surfactant. • Nickel significantly enhanced the reactivity of nanocomposite. • OH radical was the major contributor to TCE degradation. • nZVI-Ni/SPS system is more effective than conventional Fenton system. Trichloroethylene (TCE) is chloride organic solvent used in industrial process and frequently detected as one of contaminants in groundwater. In present study, nano zero valent iron-nickel composite (nZVI-Ni) was prepared successfully by ion exchange process and investigated as a proficient sodium persulfate (SPS) activator for the removal of TCE in Fenton-like oxidation system. The physico-chemical characteristics, structure, and surface morphology of the prepared nZVI-Ni nanocomposite was analyzed through energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM), N 2 adsorption-desorption, transition electron microscopy (TEM), X-ray diffractometry (XRD) and X-ray photoelectron spectroscopy (XPS). The experimental results obtained from batch tests in lab showed that more than 95% of TCE could be removed efficiently at nZVI-Ni/SPS/TCE molar ratio of 4/4/1 within 120 min at 20 °C. Further scavenging tests were designed to examine the presence of HO, SO 4 − and O 2 − radicals and verified the major role of HO radical in the nZVI-Ni/SPS system for the complete removal of TCE. Moreover, the generation of HO radicals in the system was confirmed through electrons paramagnetic resonance (EPR) of nZVI-Ni composite. The influence of surfactants on TCE removal was tested and the results showed that the percentage removal of TCE was recorded as 97.75%, 95.63% and 77.50% in the presence of Tween-80, BRIJ-35 and TX-100 surfactants at the nZVI-Ni/SPS/TCE molar ratio of 80/80/1, respectively. Results of TCE degradation in real groundwater revealed that nZVI-Ni can be applicable and is a promising catalyst for TCE removal in in-situ chemical oxidation (ISCO) practice. In Summary, these significant findings strongly demonstrate the feasibility and potential of nZVI-Ni activated SPS process as an alternative technique for TCE contaminated groundwater remediation. [ABSTRACT FROM AUTHOR]

• Glutamate (Glu) significantly enhanced carbon tetrachloride (CT) degradation. • O 2 − was one of the primary reactive species responsible to degrade CT. • The introduction of Glu benefited the Fe(III)/Fe(II) recycle and OH generation. • Simultaneous removal of CT and trichloroethene was attained. In this study, we examined the effects of chelators on reductive degradation of carbon tetrachloride (CT) in Fe(II) activated CaO 2 system in the presence of methanol (MeOH). The results suggested that glutamate (Glu) could significantly enhance CT degradation percent with around 25.9% increase in 20 min at the initial CaO 2 /Fe(II)/MeOH/Glu/CT molar ratios of 20/20/10/10/1. In the system, MeOH and Glu acted through different mechanisms, in which MeOH was used to directly stimulate the reductants formation and its reactivity, whereas Glu was acted to keep relatively high soluble iron and thus promote Fenton reaction. The results of scavenging tests suggested that O 2 − was one of the reductive radicals for CT depletion and the mechanism of CT degradation was significantly distinguished from trichloroethene (TCE) degradation which was primarily through oxidation by OH. CH 2 Cl 2 , C 2 Cl 4 , and C 2 Cl 6 were detected as the intermediates accompanied by CT destruction, and a reduction mechanism for CT degradation by the CaO 2 /Fe(II)/MeOH/Glu process was proposed accordingly. Finally, the simultaneous removal of CT and TCE was achieved in the CaO 2 /Fe(II)/MeOH/Glu system, indicating a potential technique for complex contaminated sites remediation. [ABSTRACT FROM AUTHOR]

• PPCPs in the aquatic environment near the largest landfill in China was studied. • Concentration of PPCPs in groundwater decreased with the distance from landfill. • Composition of PPCPs in groundwater was similar to that in raw landfill leachate. • Impacts of studied landfill on PPCPs in the surface water were negligible. Landfill leachates are identified as a significant source of pharmaceutical and personal care products (PPCPs), which might pose a threat to groundwater and surface water nearby the landfill. However, knowledge of PPCP contamination in the surrounding water environment of landfills is very limited. Here we investigated eighteen PPCPs in water environment near the largest landfill in China, focusing on their occurrences and spatial distribution, as well as the environmental risks. The results showed the concentration of target PPCPs was below the limit of quantification (

In this study, ferrous sulfide (FeS) was introduced to nano calcium peroxide (nCP)/Fe(III) system to facilitate the generation of Fe(II), more than 90% of naphthalene (NAP) could be removed at a wide pH range of 3–9. As a heterogeneous reductant, FeS could mitigate competitive reactions with reactive oxygen species (ROS), which favored the NAP degradation. As evidenced by scavenging experiments, HO• was the major ROS contributing to NAP degradation. The role of sulfur species (S2−, SO 3 2−, and S 2 O 3 2−) in nCP/Fe(III) system was investigated with S 2 O 3 2− showing the preferable reactivity in Fe(III) reduction. In addition, the surface-bound HO• and surface Fe(II) were detected and the role of them on NAP degradation was revealed and concluded that both dissolved and surface Fe(II) contributed to NAP degradation, whereas surface-bound HO• was not superior to solution HO• in degrading NAP. Furthermore, nCP/Fe(III)/FeS system showed high feasibility to different solution matrixes and various types of water as well as the broad-spectrum reactivity to other toxic organic pollutants, exhibiting promise for practical application to remediate complex contaminants. [Display omitted] • FeS played a vital role in accelerating Fe(II)/Fe(III) circulation. • The competitive reactions in nCP/Fe(III)/FeS system could be minimized. • Mechanisms of NAP degradation in nCP/Fe(III)/FeS system were revealed. • NAP degradation performances in various water matrixes were investigated. • Excellent reactivity for other organic contaminants was achieved. [ABSTRACT FROM AUTHOR]

[Display omitted] • CT removal could be effectively achieved with surfactant presence in Fenton system. • Radical scavenger and EPR tests revealed that surfactant radicals (R•CHOH) with TW-80 presence, and O 2 −• and CO 2 −• with SDS presence were responsible for CT degradation. • Surfactant solutions could be recycled for CT solubilization and degradation. • Significant CT removal in actual groundwater containing TW-80 or SDS was achieved. This study investigates the mechanisms of surfactants in surfactant-in situ chemical oxidation (S-ISCO) for enhanced degradation of perchlorinated organic contaminants. The addition of Tween-80 (TW-80) or sodium dodecyl sulfate (SDS) in Fenton system resulted in a significant improvement in carbon tetrachloride (CT) removal from 6.2 % to 97.2 % and from 8.2 % to 91.8 %, respectively. Upon further analysis of free radical quenching studies and electron paramagnetic resonance (EPR) tests, it was observed that surfactant radicals were responsible for CT removal with TW-80 presence, while superoxide radicals (O 2 −•) and carbon dioxide radicals (CO 2 −•) were the primary radicals with SDS presence. The dechlorination of CT reached 82.1 % and 75.3 % with TW-80 or SDS presence, respectively, indicating that most of the degraded CT could be completely mineralized. The possible degradation pathways of CT were proposed based on the detected intermediates. Additionally, degradation of various single or mixed chlorinated hydrocarbon contaminants with TW-80 or SDS presence in Fenton system was performed. The study also assessed the influence of different solution matrixes on CT degradation and the impact of the recovered surfactant solution after reaction on CT solubilization and removal. In summary, this study provides theoretical support for groundwater remediation with perchlorinated contaminants when containing surfactants. [ABSTRACT FROM AUTHOR]

Metal-organic frameworks (MOFs) as precursors for catalysts has drawn growing attentions. In this study, heterojunction Co 3 O 4 –CuO doped carbon materials (noted as Co 3 O 4 –CuO@CN) were prepared by direct carbonization of CuCo-MOF in air. It was found that the Co 3 O 4 –CuO@CN-2 exhibited excellent catalytic activity with the highest Oxytetracycline (OTC) degradation rate of 0.0902 min−1 at 50 mg/L of Co 3 O 4 –CuO@CN-2 dosage, 2.0 mM of PMS and 20 mg/L of OTC, which was 4.25 and 4.96 times that of CuO@CN and Co 3 O 4 @CN, respectively. Furthermore, Co 3 O 4 –CuO@CN-2 was efficient over a wide pH range (pH 1.9–8.4), and possessed good stability and reusability without OTC degradation decrease after five consecutive uses at pH 7.0. In a comprehensive analysis, the rapid regeneration of Cu(II) and Co(II) is responsible for their excellent catalytic performance, and the p-p heterojunction structure formed between Co 3 O 4 and CuO acts as an intermediary of electron transfer to accelerate PMS decomposition. Moreover, it was interesting to find that Cu rather than Co species played a vital role in the PMS activation. The quenching experiments and electron paramagnetic resonance demonstrated that . OH, SO 4 •−, and 1O 2 were the reactive species responsible for oxidation of OTC and the non-radical pathway triggered by 1O 2 was dominant. [Display omitted] • The k obs of Co 3 O 4 –CuO@CN-2 was 4.25 and 4.96 times that of CuO@CN and Co 3 O 4 @CN. • 1O 2 was the dominant species responsible for elimination of OTC. • The heterojunction and fast regeneration of Cu(II) and Co(II) accelerated catalytic activity. • Cu rather than Co species played a vital role in the PMS activation. • The Co 3 O 4 –CuO@CN-2 showed excellent stability and reusability for degradation of OTC. [ABSTRACT FROM AUTHOR]

The application of S(IV) for the regeneration of Fe(II) has been widely investigated. As the common S(IV) sources, sodium sulfite (Na 2 SO 3) and sodium bisulfite (NaHSO 3) are soluble in the solution, resulting in excessive SO 3 2− concentration and redundant radical scavenging problems. In this research, calcium sulfite (CaSO 3) was applied as the substitution for the enhancement of different oxidant/Fe(II) systems. The advantages of CaSO 3 could be summarized as follows: (1) it could sustainedly supplement SO 3 2− for Fe(II) regeneration, preventing radical scavenging and unnecessary reagent waste; (2) the cost and toxicity of CaSO 3 were extremely lower than that of other S(IV) sources; (3) the concentration of reactive species increased in the presence of CaSO 3 ; and (4) after the reaction, SO 4 2− would form CaSO 4 precipitate, which would not increase the burden of SO 4 2− in the solution. In the participation of CaSO 3 , the removal of trichloroethylene (TCE) and other organic contaminants were significantly promoted and different enhanced systems had high tolerance on complex solution conditions. The major reactive species in different systems were determined through qualitative and quantitative analyses. Eventually, the dechlorination and mineralization of TCE were measured and the differentiated degradation pathways in different CaSO 3 -enhanced oxidants/Fe(II) systems were elucidated. [Display omitted] • CaSO 3 was introduced in different oxidants/Fe(II) systems for the removal of various organic contaminants. • The advantages and enhanced mechanisms in CaSO 3 over other S(IV)-based chemicals were compared. • The major reactive species and their quantities were determined. • The differentiated degradation pathways of TCE in various CaSO 3 -enhanced oxidants/Fe(II) systems were elucidated. • The effects of complex solution conditions on contaminant removal were demonstrated. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The oxidation capabilities of CaO 2 /Fe(II) and CaO 2 /Fe(III) systems were compared. • Fe(II)/Fe(III), H 2 O 2 , HO, and intermediate products are evaluated in both systems. • An optimal implementation strategy for the CaO 2 application was proposed. • The strategy derived from benzene degradation works for TCE degradation. Abstract This study conducted a comparison of the CaO 2 -based Fenton (CaO 2 /Fe(II)) and Fenton-like (CaO 2 /Fe(III)) systems on their benzene degradation performance. The H 2 O 2 , Fe(II), Fe(III), and HO variations were investigated during the benzene degradation. Although benzene has been totally removed in the two systems, the variation patterns of the investigated parameters were different, leading to different benzene degradation patterns. In terms of the Fe(II)/Fe(III) conversion, the CaO 2 /Fe(II) and CaO 2 /Fe(III) systems were actually inseparable and had the inherent mechanism relationships. For the CaO 2 /Fe(III) system, the initial Fe(III) must be converted to Fe(II), and then the consequent Fenton reaction could be later developed with the regenerated Fe(II). Moreover, some benzene degradation intermediates could have the ability to facilitate the transformation of the Fe(III) to Fe(II) without the classic H 2 O 2 -associated propagation reactions. By varying the Fe(II) dosing method, an effective degradation strategy has been developed to take advantage of the two CaO 2 -based oxidation systems. The proposed strategy was further successfully tested in TCE degradation, therefore extending the potential for the application of this technique. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • nZVI-PDA@rGO catalyst was applied into oxidative environments to remove PHE. • nZVI-PDA@rGO had a better catalytic reactivity than nZVI for PHE removal. • HO and SO 4 − were the predominant radicals in the nZVI-PDA@rGO/SPS, PMS system. • PHE degradation pathways were proposed in the two SO 4 − based oxidative systems. Abstract The ability of SO 4 − based advanced oxidation processes activated by nano zero-valent iron (nZVI) on reduced graphene oxide (rGO) functionalized by polydopamine (PDA) (nZVI-PDA@rGO) in degradation of phenanthrene (PHE) was investigated under various environmental conditions. The results showed that, compared with nZVI, the catalytic degradation of PHE was enhanced after anchoring nZVI on the PDA@rGO nanosheet in the activation of sodium persulfate (SPS) and peroxymonosulfate (PMS). The maximum PHE removal efficiency reached 95.9% and 98.7% in the nZVI-PDA@rGO/SPS (50 mg L−1/0.3 mM) and nZVI-PDA@rGO/PMS (50 mg L−1/0.0375 mM) systems, respectively. The effects of pH, anions and humic acid (HA) on the PHE degradation were tested in the nZVI-PDA@rGO coupling with PMS or SPS system. The higher PHE removal could be maintained in the nZVI-PDA@rGO/SPS system at pH up to 7.74 and in the nZVI-PDA@rGO/PMS system at pH up to 7.86, respectively. Cl− had a positive effect on PHE removal in both SPS and PMS systems, while a negative effect was observed in the presence of SO 4 2−, NO 3 − and HCO 3 − (HCO 3 − > SO 4 2− > NO 3 −). In addition, the PHE removal was inhibited significantly after addition of 50 mg L−1 HA. The radical scavenger tests were carried out to identify the dominant reactive oxygen species (ROSs), which demonstrated that SO 4 − and HO were the two primary ROSs responsible for the PHE removal. The intermediate products were identified by LC-MS and the degradation pathway of PHE was proposed. [ABSTRACT FROM AUTHOR]

Calcium peroxide (CaO 2 ) is a stable hydrogen peroxide (H 2 O 2 ) carrier, and the CaO 2 /Fe(II) system has been applied for treatment of various pollutants. It is commonly reported in the literature that hydroxyl radical (HO ) and superoxide radical anions (O 2 − ) are the two main reactive oxygen species (ROSs) generated in the CaO 2 /Fe(II) system. However, many of the reported results were deduced from degradation performance rather than specific testing of radical generation. Thus, the specific generation of ROSs and the influence of system conditions on ROSs yield are still unclear. To our knowledge, this is the first study specifically focusing on the generation of HO and O 2 − in the CaO 2 /Fe(II) system. Experimental conditions were optimized to investigate the production of HO and O 2 − . The results showed the influences of CaO 2 , Fe(II), and solution pH on HO and O 2 − generation, and the HO generation efficiency was reported for the first time. In addition, the ROSs generation pathways in the CaO 2 /Fe(II) system were elucidated. A strategy for enhancing HO yield is developed, based on the continuously dosing Fe(II). This proposed strategy has implications for the effective application of in situ chemical oxidation employing CaO 2 /Fe(II) for groundwater remediation. [ABSTRACT FROM AUTHOR]

Abstract A novel and highly effective adsorbent LHMS (lanthanum hydroxide loaded on molecular sieve) for phosphate (PO 4) removal was investigated for the first time, possessing huge surface area (582.9836 m2 g−1) and adsorption capacity (12.2158 mg g−1) under the circumstance of pH = 5 and 5 mg L−1 phosphorus solution. Adsorption capacity of the adsorbent showed up the increasing trend with the increase of La contents after mixing Ce, and decreased with the elevation of temperature. The adsorption process followed the pseudo-second-order kinetic model and Freundlich, as well as Termkin, isotherm model, indicative of the existence of chemisorption and strong intermolecular interactions (i.e. ligand exchange). The strong binding between La and phosphate (LaPO 4) could not be readily substituted by most anions and humic acid. The potential mechanism for the adsorption process by LHMS was explained based on the SEM-EDS, XRD, XPS, FTIR, and NMR analysis. Furthermore, the formation of LaPO 4 on account of ligand exchange reaction was considered to be the primary pathway for selective adsorption by the immobilized La(OH) 3. The above findings displayed that LHMS was deemed to be the promising adsorbent, efficiently removing PO 4 from real wastewater, and it would open the new avenues for the application of adsorbents in the field of wastewater treatment. Graphical abstract Image 1 Highlights • LHMS was the first La-based adsorbent composed of available molecular sieve. • Compared with Ce, loading La on MS was better adsorbent for PO 4 removal. • LaPO 4 was the main pathway by ligand exchange based on systematic characterizations. • LHMS has been proved to possess the practical application in real wastewater treatment. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • nZVI-PDA@rGO catalyst was applied into oxidative environments to remove TCE. • nZVI-PDA@rGO had the better stability against oxidation exposed to the air. • nZVI-PDA@rGO had a better catalytic reactivity than nZVI-rGO at a lower dosage. • nZVI-PDA@rGO depended mostly on SO 4 − by contrast of nZVI-rGO relying on HO. Abstract Nano zero-valent iron (nZVI) particles with higher reactivity have been recognized as more efficient catalysts than Fe(II) for the groundwater remediation. The rapid emergence of novel catalyst supports efficiently prevent the rapid aggregation of nZVI and further improve catalytic reactivity. However, the lack of ability to avoid the potential oxidation of bare nZVI-support structure in air environment hinders its wider application in the actual contaminated sites. In this study, nZVI on reduced graphene oxide (rGO) functionalized by polydopamine (PDA) (nZVI-PDA@rGO) was synthesized successfully and applied into sodium persulfate (SPS), potassium monopersulfate (PMS) and H 2 O 2 oxidative environments to remove trichloroethylene (TCE). For comparison, nZVI supported on solely rGO was prepared. The XRD test displayed the stronger stability of α-Fe(0) in nZVI-PDA@rGO catalyst against oxidation exposed to air. Compared with nZVI-rGO, a core shell structure of nZVI-PDA@rGO was observed in TEM image obviously. The dosage tests showed nZVI-PDA@rGO had a better catalytic reactivity than nZVI-rGO for TCE removal at lower catalyst and oxidant dosages, i.e. PMS dosage: 0.3 mM, catalyst dosage: 50 mg L−1, TCE removal: 45.0% (nZVI-rGO) up to 99.6% (nZVI-PDA@rGO). TCE removal mechanisms were revealed through radical scavenger tests, demonstrating sulfate radicals played more important role in nZVI-PDA@rGO catalyzed-oxidant systems. [ABSTRACT FROM AUTHOR]

The in situ generation of hydrogen peroxide (H 2 O 2 ) for water treatment is more practical than the use of liquid H 2 O 2 , which is costly to store and transport. Calcium peroxide (CaO 2 ), a solid carrier of H 2 O 2 , can release H 2 O 2 on dissolution in water. However, the constant H 2 O 2 release rate of CaO 2 has been a bottleneck constraining its wider application. In this study, a practical electrochemical method using a divided cell is developed to control the rate of release of H 2 O 2 from CaO 2 . The results show that the rate of H 2 O 2 release from CaO 2 is enhanced in the anolyte. The increase in H 2 O 2 release is positively correlated with the current. Under a current of 100 mA, the H 2 O 2 concentration was 2.5 times higher after 30 min of electrolysis than in the control experiment in which no current was applied. Water electrolysis in the anodic compartment generates protons that not only: (i) enhance dissolution of CaO 2 and release of H 2 O 2 , but also (ii) neutralize the alkaline pH resulting from CaO 2 dissolution, thus providing new advantages for the use of CaO 2 . This effective technique may be suitable for the sophisticated control of H 2 O 2 release in environmental applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • The homogeneous reaction played a dominant role in H 2 O 2 /FeS 2 /NAP system. • FeS 2 performed best compared with S-nZVI and FeS. • Sulfur intermediates from FeS 2 facilitated the iron redox cycle. • FeS 2 performed well in complex environment conditions. Fe-containing natural minerals, such as pyrite, have been conducted an extensive study in Fenton-like processes, however, answers for the role of homogeneous and heterogeneous reactions and their application potentials need to be theoretically demonstrated. In this study, the performance and mechanism of Fenton-like process catalyzed by pyrite were investigated by surface characterizations and degradation experiments using naphthalene as a target contaminant. First, the major role of homogeneous reaction in the naphthalene degradation in H 2 O 2 /pyrite system was confirmed by iron determination and iron quenching tests, where 2,2′-bipyridine was used as the iron quencher. Second, it was clarified that sulfur species including polysulfides, elemental sulfur, and thiosulfate facilitated the Iron redox cycle and the yield of reactive oxygen species, thus enhanced the degradation of naphthalene. Moreover, compared with sulfidated nanoscale zero valent iron and ferrous sulfide, pyrite exhibited superiority in naphthalene degradation due to higher reaction stoichiometry efficiency (0.31) and lower running cost (77 RMB (kg naphthalene)−1). Finally, pyrite showed excellent performance for various pollutants removal and in multiple water environments. This work provides the underlying mechanisms of H 2 O 2 /pyrite process and a solid step forward to pyrite application in the remediation of naphthalene contaminated water. [ABSTRACT FROM AUTHOR]

• CaSO 3 , slow-released SO 3 2− source, was introduced in S(IV)-based AOPs. • Fe(III)/CaSO 3 system was established for the removal of various organic contaminants. • The major ROS, contaminants degradation mechanism, and pathways were revealed. • The degradation performance of contaminants in complex solution matrixes was investigated. • Extensive applications and broad-spectrum of Fe(III)/CaSO 3 system were demonstrated. S(IV)-based advanced oxidation process has been applied for contaminants remediation. However, as a traditional source of sulfite (SO 3 2−), Na 2 SO 3 is extremely soluble in water, resulting in a high concentration of SO 3 2− to quench the generated reactive oxygen species (ROS). In this work, CaSO 3 was introduced instead of Na 2 SO 3 for its slow-released SO 3 2− ability and Fe(III)/CaSO 3 system was established for the removal of trichloroethylene (TCE) and other organic contaminants. The degradation efficiency of TCE reached 94.0% and TCE could be completely dechlorinated and mineralized, while the removal of other contaminants was all over 85.0% at the optimal tested conditions. Through EPR detection, ROS scavenging and probe tests, and quantification of ROS amounts, it was concluded that the dominant ROS in Fe(III)/CaSO 3 system were SO 4 −· and 1O 2 , of which the transformation mechanism of SO 4 −· to 1O 2 was revealed and demonstrated comprehensively. The synergistic contaminants degradation performance in different sulfur-iron-containing systems and in the presence of oxidants was evaluated. The effects of various solution conditions were assessed and Fe(III)/CaSO 3 system was of higher resistance on complex solution matrixes, suggesting the broad-spectrum and application perspective for the remediation of complex contaminants in actual water. [ABSTRACT FROM AUTHOR]

In this work, the effect of different desorbents (low molecular weight organic acids (LMWOAs), surfactants, and inorganic salts) on naphthalene (NAP) desorption in soil was investigated, and the results showed that NAP desorption pattern fitted the pseudo-second-order kinetics. The addition of LMWOAs, especially citric acid (CA), could stimulate the reactive oxygen species (ROS) generation and NAP degradation in Fe(II) activated persulfate (PS) system, while the presence of surfactants and CaCl 2 could inhibit the NAP removal due to the competitive consumption of ROS. The maximum removal of NAP was 97.5% within 120 min at the PS/Fe(II)/CA/NAP molar ratio of 15/5/1/1, and the pseudo-first-order kinetic constant of NAP removal increased from 0.0110 min−1 to 0.0783 min−1 with the addition of CA. Compared with surfactants and inorganic salts, LMWOAs, especially CA, were more suitable as desorbent in soil washing coupled with in situ chemical oxidation technique. Moreover, 1.86 mg L−1 desorbed amount and 36.1% removal of NAP from soil could be obtained with the presence of 1 mM CA. Finally, the significant removal of NAP and other contaminants (phenanthrene, fluoranthene, and benzene series) in actual groundwater could provide theoretical basis and technical support for the remediation of organic contaminated sites with desorbents. [Display omitted] This study systematically reported the performance and mechanisms of NAP desorption and degradation in the presence of three different kinds of desorbents. The kinetics of NAP desorption and degradation with desorbents were elucidated. The effect of different desorbents on NAP removal was compared and LMWOAs, especially CA, were evaluated to be the optimal desorbents in the soil washing coupled with ISCO process. The enhancement of LMWOAs for NAP degradation was further illuminated. The significant removal of NAP in actual groundwater and other contaminants (PHE, FLT, and BTEX) could provide technical support for the remediation of organic contaminated sites with desorbents. • Effect of different desorbents on NAP desorption and degradation was investigated. • The kinetics of NAP desorption and degradation with desorbents was elucidated. • SO 4 −• and HO• contributed to NAP degradation in PS/Fe(II) system with desorbents. • Effective removal of NAP in actual groundwater containing desorbents was achieved. [ABSTRACT FROM AUTHOR]

Naphthalene (NAP) has received increasing concern due to frequent detection in groundwater and harm to humans. In this study, FeS 2 was selected as a novel catalyst to activate nano calcium peroxide (nCP) for NAP degradation. Batch experiments were conducted in a 250 mL glass reactor containing 0.1 mM NAP solution to investigate the effect of reagents dosage, pH, air conditions (with or without N 2 purge), and different solution matrixes on NAP degradation. Scavenging tests, electron paramagnetic resonance (EPR) spectrum, and radical probe tests were conducted to identify the main radicals. Results indicated that over 96% NAP was removed in a wide pH range (3.0–9.0) within 180 min at optimal dosage of nCP = 1.0 mM and FeS 2 = 5.0 g L−1 in nCP/FeS 2 system. Aerobic condition was more beneficial to NAP degradation and the system could tolerate complex solution conditions. Moreover, HO• was determined to be responsible for NAP degradation. NAP degradation intermediates were detected by gas chromatography-mass spectrometry (GC-MS) and the possible degradation pathways were revealed. Finally, the efficient degradation of other organic pollutants confirmed the broad-spectrum reactivity of the nCP/FeS 2 system. Overall, these findings strongly demonstrated the potential applicability of nCP/FeS 2 system in remediating organic contaminated groundwater. [Display omitted] • nCP/FeS 2 system could degrade NAP efficiently at a wide pH range of 3.0–9.0. • FeS 2 played a significant role in Fe(II)/Fe(III) cycle. • Mechanisms of NAP degradation in nCP/FeS 2 system were revealed. • Performance of NAP degradation in different solution matrixes was investigated. • Excellent reactivity for other organic pollutants in nCP/FeS 2 system was achieved. [ABSTRACT FROM AUTHOR]

[Display omitted] • UV/PMS could efficiently inactivate ARB and control the risk of photoreactivation. • bla NDM-1 was greater resistance to UV/PMS than bla OXA-58 in the same plasmid. • ARGs base pairs number and length were responsible for ARGs removal. • 1O 2 plays an important role on the plasmid-encoded ARGs removal in UV/PMS. The super-resistant bacteria that produce the New Delhi metallo-β-lactamase 1 (NDM-1) enzyme are becoming a conceivably major worldwide clinical issue with serious consequences. Studying the disinfection and mechanism of super-resistant bacteria and their antibiotic resistance genes (ARGs) is crucial for controlling their spread in the water environment. In this study, the disinfection of the super-resistant bacterium Acinetobacter sp. CS-2 and its transferable ARGs (plasmid-encoded bla NDM-1 and bla OXA-58) by ultraviolet radiation (UV), peroxymonosulfate (PMS), and ultraviolet/peroxymonosulfate (UV/PMS) exposure were investigated. UV/PMS could completely inactivate CS-2 and control the photoreactivation risk, while bacteria that underwent UV and PMS treatment had survival ratios of 0.22% and 0.28%, respectively. The removal efficiencies of bla NDM-1 and bla OXA-58 ranged from 3.64 to 4.05 log, and the advantage of UV/PMS treatment on ARGs damage was further identified by gel electrophoresis analysis. The removal efficiency of bla NDM-1 was lower than that of bla OXA-58 , which was attributed to the low number of adjacent 5′-TT-3′ harbored by bla NDM-1. The removal rate constants of the ARGs by UV treatment were significantly correlated with the number of adjacent base pairs (e.g., 5′-TT-3′, 5′-CT-3′, 5′-TC-3′ and 5′-CC-3′) and length, with R -values ranging from 0.9044 to 0.9512. Singlet oxygen (1O 2) played a vital role in the reduction of bla NDM-1 and bla OXA-58 in the UV/PMS treatment. UV/PMS showed high removal efficiency under natural pH conditions and in the presence of various aqueous ions (e.g., Cl−, SO 4 2− and HCO 3 −). Overall, this study provides new understandings and theoretical support for the risk control of super-resistant bacteria and plasmid-encoded ARGs. [ABSTRACT FROM AUTHOR]

The performance of naphthalene (NAP) degradation in peroxodisulfate (PDS) and peroxymonosulfate (PMS) oxidation systems by nano zero valent iron (nZVI) combined with citric acid (CA) activation was reported in aqueous solution and soil slurry medium. The results in aqueous solution tests indicated that 98.1% and 98.9% of NAP were individually degraded in PDS/nZVI/CA and PMS/nZVI/CA systems within 2 h when the dosages of PDS, PMS, nZVI and CA were 1.0 mM, 0.1 mM, 0.2 mM and 0.1 mM, respectively. The consequences of scavenging tests and electron paramagnetic resonance detection demonstrated that HO• and SO 4 −• were the key factors on NAP removal. The presence of surfactants could consume ROSs and inhibit NAP removal. In addition, GC-MS was applied for the determination of NAP degradation intermediates, and three possible NAP degradation pathways were proposed in PDS oxidation process and two pathways in PMS oxidation process, respectively. The results in soil slurry medium showed that the presence of CA could promote the dissolution of soil minerals and the desorption of NAP from soil medium. 93.5% and 96.8% degradation of NAP were obtained in PDS/nZVI/CA and PMS/nZVI/CA systems within 24 h. Besides, the existence of DOM in soil could promote Fe(II)/Fe(III) cycle and NAP degradation through electron transfer. Based on the NAP degradation performance in the actual groundwater and soil medium, the above findings could provide basis and strong support for the potential application of PDS/nZVI/CA and PMS/nZVI/CA systems in the remediation of NAP contaminated sites. [Display omitted] • NAP degradation in actual groundwater and soil slurry medium was investigated. • HO.• and SO 4 −• were the key factors in PDS and PMS oxidation systems. • The possible degradation pathways of NAP were proposed. • The enhancement of citric acid for NAP removal was illuminated. • The mechanism of NAP degradation influenced by DOM in soil was clarified. [ABSTRACT FROM AUTHOR]