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Virus clearance, a critical aspect of biopharmaceutical manufacturing processes, ensures the safety of biopharmaceutics. Virus filtration is widely used during biopharmaceutical downstream processes to remove viruses effectively by separating small viruses (e.g., parvovirus with a size of 18–26 nm) from biopharmaceutics (e.g., monoclonal antibodies with a size of ~12 nm) based on a size-exclusion mechanism (i.e., more than 4-log10 removal of viruses with high product recovery). This paper presents a review of key factors such as filter morphology, feed solution composition, and the performance of high-throughput virus filtration, mainly focusing on the log reduction value for virus removal efficiency. Flow interruption and protein fouling issues are also discussed. [ABSTRACT FROM AUTHOR]

Highlights: [•] A nanoporous WO3 photoanode was fabricated by electrochemical anodization. [•] We assessed the utility of the photoanode in the catalytic degradation of a dye. [•] The visible-light activity and the stability of the photoanode were examined. [•] The effects of various reaction parameters on the dye decoloration were also examined. [Copyright &y& Elsevier]

Abstract: Electrical discharge processes are emerging as water treatment technologies applicable to both the degradation of organic contaminants as well as inactivation of pathogens. Particularly as a disinfection technology, electrical discharge processes do not produce toxic byproducts, and effectively inactivate a wide spectrum of microorganisms by multiple lethal actions generated by the formation of plasma channels. This study demonstrates the inactivation of a virus using the streamer corona discharge process (SCDP) with MS2 phage as a surrogate. A rapid inactivation of MS2 phage (i.e., approximately 4loginactivation in 5min) was observed in all experimental runs conducted. Discharge conditions such as applied voltage and storage capacitance significantly affected the inactivation efficiency of MS2 phage, whereas the influence of water quality parameters was minor. In order to elucidate the mechanism of MS2 phage inactivation, potentially lethal factors that can be generated by the SCDP were selected, and their roles in the inactivation of MS2 phage were examined. As a result, effects of UV radiation, chemical oxidants, and pulsed electric fields were found to be insignificant. The shockwave generated upon plasma channel formation appears to be the most important factor responsible for MS2 phage inactivation. [ABSTRACT FROM AUTHOR]

Abstract: Fenton''s reagent (i.e., Fe[II]/H2O2) is known to generate strong oxidants capable of oxidizing a broad spectrum of organic compounds in aqueous solution. This study demonstrates the successful inactivation of MS2 coliphage (MS2) by the oxidants produced from Fenton''s reagent. The inactivation process of MS2 by Fenton''s reagent was found to proceed in two distinct stages. The first stage inactivation, which took place rapidly within 1 min reaction time, was mainly achieved by the reaction of Fe(II) with H2O2 (i.e., the Fenton reaction). The second stage, which occurred by the catalytic reactions of Fe(III) with H2O2, exhibited much slower inactivation than the first stage. The rate of MS2 inactivation increased as pH decreased from 8.0 to 6.0. The addition of oxalate and humic acids significantly inhibited the MS2 inactivation, whereas 1,10-phenanthroline and bipyridine resulted in a gradual and steady inactivation of MS2. These observations on the effects of pH and iron-chelating agents indicate that oxidants formed on the surface or inside MS2 are responsible for the inactivation. [Copyright &y& Elsevier]

Abstract: Ferric ion (Fe[III]) catalyzes the decomposition of hydrogen peroxide (H2O2) into strong oxidants such as hydroxyl radical (erryl ion (Fe[IV]) through the redox cycling of the iron couple (Fe[II]/Fe[III]). The use of these reactions for the catalytic oxidation of organic compounds is usually limited to the acidic pH region due to the low solubility of Fe(III) and the low efficiency of oxidant production at neutral pH values. The addition of phosphotungstate (PW12O40 3−), a polyoxometalate, extends the working pH range of the Fe(III)/H2O2 system up to pH 8.5. PW12O40 3− forms a soluble complex with iron that converts H2O2 into oxidants. The coordination of Fe(II) by PW12O40 3− also alters the mechanism of the reaction of Fe(II) with H2O2 at neutral pH, resulting in formation of an oxidant capable of oxidizing aromatic compounds. The base-catalyzed hydrolysis of PW12O40 3− gradually results in inactivation of the catalyst. In the absence of Fe(III), PW12O40 3− was completely hydrolyzed after 1 day at pH 7.5, whereas the Fe(III)–PW12O40 3− complex was active for at least 4 days under the same conditions. [Copyright &y& Elsevier]

Nanoparticulate zero-valent iron (nZVI) rapidly reacts with oxygen to produce strong oxidants capable of transforming organic contaminants in water. However, the low yield of oxidants with respect to the iron added normally limits the application of this system. Bimetallic nickel-iron nanoparticles (nNi-Fe; i.e., Ni-Fe alloy and Ni-coated Fe nanoparticles) exhibited enhanced yields of oxidants compared to nZVI. nNi-Fe (Ni-Fe alloy nanoparticles with [Ni]/[Fe] = 0.28 and Ni-coated Fe nanoparticles with [Ni]/[Fe] = 0.035) produced approximately 40% and 85% higher yields of formaldehyde from the oxidation of methanol relative to nZVl at pH 4 and 7, respectively. Nicoated Fe nanoparticles showed a higher efficiency for oxidant production relative to Ni-Fe alloy nanoparticles based on Ni content Addition of Ni did not increase the oxidation of 2-propanol or benzoic acid, indicating that Ni addition did not enhance hydroxyl radical formation. The enhancement in oxidant yield was observed over a pH range of 4-9. The enhanced production of oxidant by nNi-Fe appears to be attributable to two factors. First, the nNi-Fe surface is less reactive toward hydrogen peroxide (H2O2) than the nZVI surface, which favors the reaction of H2O2 with dissolved Fe(ll) (the Fenton reaction). Second, the nNi-Fe surface promotes oxidant production from the oxidation of ferrous ion by oxygen at neutral pH values. [ABSTRACT FROM AUTHOR]

l Roles of •OH, •Cl, SO 4 •−, and Fe(IV) were interrogated to reduce NDMA-FP. l Activated PDS showed a higher % RSE as compared to H 2 O 2 treatment. l Increasing pretreatment pH overall alleviated the reduction in NDMA-FP. l •OH alone was ineffective and UV/H 2 O 2 even increased NDMA-FP of ranitidine. l e-Fenton and e-PDS were cost-effective method for RO brine treatment. This study investigated the effects of thirteen (photo/electro) chemical oxidation processes on the formation potential (FP) of N -nitrosodimethylamine (NDMA) during the chloramination of ranitidine in reverse osmosis (RO) permeate and brine. The NDMA-FP varied significantly depending on the pretreatment process, initial pH, and water matrix types. At higher initial pH values (> 7.0), most pretreatments did not reduce the NDMA-FP, presumably because few radical species and more chloramine-reactive byproducts were generated. At pH < 7.0, however, electrochemical oxidation assisted by chloride and Fe2+/H 2 O 2 , catalytic wet peroxide oxidation and peroxydisulfate-induced pretreatments removed up to 85% of NDMA-FP in the RO brine. Ultraviolet (UV) irradiation or prechlorination alone did not reduce the NDMA-FP effectively, but combined UV/chlorine treatment effectively reduced the NDMA-FP. In contrast, after UV irradiation (2.1 mW cm−2 for 0.5 h) in the presence of H 2 O 2 and chloramine, NDMA formation increased substantially (up to 26%) during the post-chloramination of the RO permeate. Mass spectrometric analysis and structural elucidation of the oxidation byproducts indicated that compared with the reactive nitrogen species generated by UV/NH 2 Cl, sulfate radicals and (photo/electro)chemically generated reactive chlorine species were more promising for minimizing NDMA-FP. Unlike, the hemolytic •OH driven by UV/H 2 O 2 , the •OH from Fe(IV)-assisted pretreatments showed a significant synergistic effect on NDMA-FP reduction. Overall, the results suggest the need for a careful assessment of the type of radical species to be used for treating an RO water system containing amine-functionalized compounds. [Display omitted] [ABSTRACT FROM AUTHOR]

• Some •OH probes were over-degraded by unknown reactive species in UV/H 2 O 2 system. • Unknown reactive species was not found in dark •OH production systems. • Unknown reactive species seems related to unidentified transitional state H 2 O 2. • [•OH] ss can be overestimated depending on the type of •OH probe. The UV/H 2 O 2 process is a benchmark advanced oxidation process (AOP) that in situ generates highly reactive and nonselective hydroxyl radical (•OH) to oxidatively destroy a wide range of organic compounds. Accurately quantifying the concentration of short-lived •OH is essential to predict process performance, optimize the operation parameters, and compare with other process options. The •OH concentration is typically measured using organic probe molecules that react with •OH but not with other oxidants. In the extremely well-characterized UV/H 2 O 2 system in which •OH is proven to be the dominant oxidant, using photolysis-resistant probes such as benzoic acid and its derivatives is a widely agreed and practiced norm. We herein report that certain •OH probe compounds can be degraded in UV/H 2 O 2 system by unknown reactive species that has not been reported in the past. Several common organic probes, particularly p -substituted benzoic acid compounds (i.e., p -hydroxybenzoic acid, p -chlorobenzoic acid, and p -phthalic acid), were found to be vulnerable to attack by the unknown reactive species, leading to false quantification of •OH concentration under high radical scavenging conditions. Lines of evidence obtained from a series of •OH scavenging experiments performed under various conditions (i.e., different concentrations of H 2 O 2 , •OH probe compounds, and dissolved oxygen) point toward excited state H 2 O 2. The results from this study suggest the importance of using appropriate •OH probe compounds in mechanistic studies and needs for considering the unidentified role of excited state of H 2 O 2 on the UV/H 2 O 2 process and related AOPs. [ABSTRACT FROM AUTHOR]

Silver ions have been widely used as an effective water disinfectant or antimicrobial material for many decades. In addition, the application of silver ions in combination with other biocides, especially UV254 (UV-C) irradiation, was reported to be effective in enhancing its germicidal activity. However, it is not yet known how UV-A (300–400nm) or visible light irradiation, which have little or no antimicrobial activities, affect microorganism inactivation by silver ions. This study newly reports that the inactivation efficiencies of Escherichia coli and MS-2 phage by silver ions were significantly enhanced by UV-A or visible light irradiation. UV-A irradiation enhanced the inactivation of E. coli and MS-2 phage by 3.0 and 2.5log/30min, respectively, as compared with the simple summated value of individual applications of silver ions and UV-A. A similar trend was observed with visible light irradiation (>400nm) although the level of enhancement was lessened. The photochemical reaction of silver–cysteine complex was suggested as a possible mechanism for this enhancement. Spectrophotometric and MALDI-TOF mass analyses support the fact that silver ions coupled with light irradiation causes critical cell damage through the complexation of silver ions with thiol (–SH) groups in structural or enzymatic proteins of the microorganisms and their subsequent photochemical destruction. [Copyright &y& Elsevier]

The potential of ferrate (Fe(VI)) oxidation to remove N-nitrosodimethylamine (NDMA) precursors during water treatment was assessed. Apparent second-order rate constants (k app) for the reactions of NDMA and its suspected precursors (dimethylamine (DMA) and 7 tertiary amines with DMA functional group) with Fe(VI) were determined in the range of pH 6–12. Four model NDMA precursors (dimethyldithiocarbamate, dimethylaminobenzene, 3-(dimethylaminomethyl)indole and 4-dimethylaminoantipyrine) showed high reactivity toward Fe(VI) with k app values at pH 7 between 2.6×102 and 3.2×105 M−1 s−1. The other NDMA precursors (DMA, trimethylamine, dimethylethanolamine, dimethylformamide) and NDMA had k app values ranging from 0.55 to 9.1M−1 s−1 at pH 7. In the second part of the study, the NDMA formation potentials (NDMA-FP) of the model NDMA precursors and natural waters were measured with and without pre-oxidation by Fe(VI). For most of the NDMA precursors with the exception of DMA, a significant reduction of the NDMA-FP (>95%) was observed after complete transformation of the NDMA precursor. This result was supported by low yields of DMA from the Fe(VI) oxidation of tertiary amine NDMA precursors. Pre-oxidation of several natural waters (rivers Rhine, Neckar and Pfinz) with a high dose of Fe(VI) (0.38mM=21mgL−1 as Fe) led to removals of the NDMA-FP of 46–84%. This indicates that the NDMA precursors in these waters have a low reactivity toward Fe(VI) because it has been shown that for fast-reacting NDMA precursors Fe(VI) doses of 20μM (1.1mgL−1 as Fe) are sufficient to completely oxidize the precursors. [Copyright &y& Elsevier]

Abstract: The photochemical nitrosation of dimethylamine (DMA) has been suggested as a possible pathway for the occurrence of N-nitrosodimethylamine (NDMA) in aquatic environments. The aim of this study was to investigate the formation of NDMA from the nitrosation of DMA during nitrite (NO2 −) photolysis in aqueous solution by varying several of the experimental parameters. NDMA was formed at neutral pH, in the presence of DMA and NO2 − under UV-A irradiation, and exhibited an increase in concentration with irradiation time. Increasing the concentrations of DMA and NO2 − led to enhanced NDMA formation. Through experiments employing ger (t-BuOH), und to play an important role in the production of nitrosating agents during the photolysis of NO2 −. The optimum pH for the formation of NDMA was around 10. This pH dependence was explained by the dual role of deprotonated DMA as a nucleophile, which enhances the nitrosation reaction between nitrosating agents and DMA, and a hydroxyl radical (nger, which reduces the production of nitrosating agents. A higher concentration of NDMA was obtained under N2 condition due to the lower quantum yield for NDMA photolysis in the absence of oxygen. Various anions, including phosphate ions in the buffer solution, retarded the formation of NDMA, possibly due to degradation of the nitrosating agents. [Copyright &y& Elsevier]

This study investigates the oxidative degradation of N-nitrosodimethylamine (NDMA), a probable human carcinogen, by conventional ozonation and the advanced oxidation process ozone/hydrogen peroxide (AOP O3/H2O2). The rate constants of reactions of NDMA with ozone and hydroxyl radical (•OH) were determined to be 0. 052±0. 0016M−1 s−1 and (4. 5±0. 21)×108 M−1 s−1, respectively. The experiments performed with buffered deionized water varying solution pH and employing H2O2 and HCO3 − clearly showed that the reaction with •OH dominates the NDMA oxidation during ozonation. Conventional ozonation with up to 160μM (=7. 7mgL−1) ozone led to less than 25% NDMA oxidation in natural waters. The AOP O3/H2O2 required 160–320μM ozone ([O3]0/[H2O2]0=2:1) to achieve 50–75% NDMA oxidation. However, multiple injections of ozone of the same overall dose somewhat improved the oxidant utilization efficiency by minimizing •OH scavenging contribution of oxidants. Methylamine (MA) was found to be a major amino product from NDMA oxidation initiated by •OH. The mechanism of NDMA oxidation to MA is discussed based on the results obtained in this study and the previous literature. Bromate formation may be the limiting factor for NDMA oxidation during ozonation and ozone-based AOPs in bromide-containing waters. [Copyright &y& Elsevier]

Abstract: This study systematically investigates the characteristic degradation behaviors of dimethylsulfoxide (DMSO) by the streamer corona discharge process (SCDP) in water. The analysis of the oxidized intermediates of DMSO shows that hydroxyl radical ( OH) is the main oxidant responsible for the degradation of DMSO in the SCDP. The various experiments on the degradation and mineralization of DMSO, and the effect of the OH scavenger suggest that the SCDP produces locally concentrated OHs in and around the plasma channel. This explanation was also supported by the formation of H2O2 and the effect of the OH scavenger on the H2O2 production rate in the SCDP. Based on the kinetic data for the degradation of DMSO and the production of H2O2 in the SCDP, the volume of the active region in which the OHs are concentrated, and the effective concentration of OH in that region were estimated to be 0.21μl and 5.0×10−3 M, respectively. This level of OH concentration in the SCDP is approximately 107–109 times higher than that generated in ordinary advanced oxidation processes using OH. The ramifications of the results obtained in this study on successful water treatment using the SCDP are also discussed. [Copyright &y& Elsevier]

The photolytic mechanism of N-nitrosodimethylamine (NDMA) in aqueous solution was investigated under ultraviolet (UV) irradiation at 253.7 nm, by determining the quantum yield of NDMA photolysis and analyzing the photolysis products in the pH range of 2-11 under O2 or N2 saturation. Several important photolytic behaviors of NDMA photolysis regarding the roles of dissolved oxygen and solution pH were newly observed, and novel photolytic mechanisms were proposed based on these observations. First the presence of dissolved oxygen clearly increased the quantum yield of the NDMA photolysis, and promoted the photolytic pathway leading to the formation of methylamine and nitrate. The direct oxidation of photoexcited NDMA by dissolved oxygen (photooxidation) was suggested as a novel photolytic pathway to explain the observed effect of dissolved oxygen. This photooxidation mechanism was supported by the detection of superoxide radicals during the photolysis of NDMA under O2 saturation. Second, the dependence of the quantum yield of NDMA photolysis and the yields of the known photolysis products (methylamine, dimethylamine, nitrite, and nitrate) on the solution pH were different under O2 and N2 saturation. N-Methylformamide was observed as the novel photolysis product of NDMA in the neutral pH region under N2 saturation. These pH-dependent photolytic behaviors of NDMA were successfully explained by the interaction of the photoexcited NDMA with a proton, and the pH-dependent secondary reactions between the primary photolysis products. [ABSTRACT FROM AUTHOR]

The determination of quantum yields for the photolysis of Fe(III)-hydroxo complexes is important for the quantitative investigation of hydroxyl radical (OH) production, not only in a natural water body, but also in the photo-Fenton process. A novel kinetic method, using a OH probe compound, was established for the determination of the quantum yields in this study. The method was based on measuring the pseudo-first-order rate constant of the photodecomposition of dimethylsulfoxide (DMSO) in which DMSO and its primary products scavenged the OH at an identical rate. The preliminary experiments for the photodecomposition kinetics supported the suitability of DMSOs as a probe compound for determining quantum yields. The individual quantum yields for the photolysis of the monomeric Fe(III) complexes, in the wavelength range 240–380nm, were determined by the photodecomposition kinetics of the hydroxyl radical (OH) probe compound (DMSO). The determined values of the individual quantum yields were 0.046±0.00052 for Fe3+ (H2O)6 (hexaaquo ion) and 0.69±0.025 for Fe(OH)2+(H2O)5 (hydroxypentaaquo ion) at 254nm, and showed decreasing values with increasing wavelength, in the ranges of 240–380nm. The quantum yields between 240 and 280nm were newly reported in this study, and the values obtained between 280 and 380nm were in good agreement with the literature values. [Copyright &y& Elsevier]

The thermal enhancement of the formation of ⋅OH by the hv/Fe(III)/H2O2 system (including the Fe(III)/H2O2 system) was quantitatively investigated with reaction temperatures ranging from 25 to 50 °C. A temperature dependent kinetic model for the hv/Fe(III)/H2O2 system, incorporating 12 major reactions with no fitted rate constants or activation energies, was developed, and successfully explained the experimental measurements. Particularly, the thermal enhancement of Fe(OH)2+ photolysis which is the most significant step in the hv/Fe(III)/H2O2 system was effectively explained by two factors; (1) the variation of the Fe(OH)2+ concentration with temperature, and (2) the temperature dependence of the quantum yield for Fe(OH)2+ photolysis (measured activation energy=11.4 kJ mol-1). Although in both the hv/Fe(III)/H2O2 and Fe(III)/H2O2 systems, elevated temperatures enhanced the formation of ⋅OH, the thermal enhancement was much higher in the dark Fe(III)/H2O2 system than the hv/Fe(III)/H2O2 system. Furthermore, it was found that the relative thermal enhancement of the formation of ⋅OH in the presence of ⋅OH scavengers (tert-butyl alcohol) was magnified in the Fe(III)/H2O2 system but was not in the hv/Fe(III)/H2O2 system. [Copyright &y& Elsevier]

The decolorization of the reactive dye, reactive black 5 (RB5), by the photoactivated periodate (UV/IO4-) was investigated under ultraviolet (UV) irradiation at 254 nm, and its possible mechanism based on periodate photochemistry was discussed, in order to elucidate the main oxidants involved in the decolorization of RB5 as the reaction parameters, such as the light intensity, periodate concentration, dissolved oxygen, and solution pH, were varied, with the intermittent employment of an ⋅OH scavenger. The decolorization rate of RB5 increased linearly with increasing light intensity. The decolorization rate was found to increase at low periodate concentrations (0–5 mM), but slightly decrease at higher concentrations (>5 mM). Dissolved oxygen did not have any measurable effect on the decolorization rate of the reactive dye. No pH dependence of the decolorization rate was observed over the pH range of 1.5–10, regardless of the periodate speciation. Based on these results, the main oxidants responsible for the RB5 decolorization with UV 254 were found to be ⋅OH and IO3⋅ (IVI⋅), after considering the six intermediate species which are reported to be produced as a result of periodate photolysis, namely the radical species (⋅OH, IO3⋅, and IO4⋅) and the non-radical species (O3, IO4-, and IO3-). [Copyright &y& Elsevier]

The efficient recovery of rare earth elements (REEs) from secondary sources is an urgent global challenge. Although zeolite‐imidazolate‐framework‐8 (ZIF‐8) has unique advantages for REE recovery, its nanopowder form poses a significant obstacle to its practical application. Herein, the study proposes a novel in situ strategy for shaping ZIF‐8 into hierarchical 3D center‐radial channels of a polymeric macrocapsule (PMC) via a hybrid approach. Core–shell‐type ZIF‐8‐PMC hybrids (ZIF‐8@PMC) with the intrinsic physicochemical properties of ZIF‐8 are synthesized by combining counter‐diffusion‐based in situ growth and phase transformation, enabling unprecedented REE recovery of 463.6 and 580 mg g−1 for Nd3+ and Dy3+, respectively, which are superior to that of traditional encapsulating protocols. Moreover, ZIF‐8@PMC exhibits good applicability in the simulated permanent magnet leachate with recovery efficiencies of 92.5% (Nd3+) and 81.8% (Dy3+), after five repetitive cycles because of its protective nanoporous shell layer that prevents the release of in situ‐shaped ZIF‐8 to the exterior and invasion of external particulates into the PMC. Overall, these findings demonstrate the suitability of PMC as an ideal platform for the in situ shaping of ZIF‐8 and the application of the newly proposed protocol as a promising approach to expand the applicability of ZIF‐8 in various fields. [ABSTRACT FROM AUTHOR]

Capacitive deionization (CDI) is an emerging desalination technology with an environmental-friendly operation and energy-efficient properties. However, activated carbon (AC) used for CDI electrode does not have a significant preference toward anions, leading to unnecessary energy consumption for treating fluoridated water. Hence, we achieved selective fluoride removal in CDI system using a reduced graphene oxide/hydroxyapatite composite (rGO/HA), a novel fluoride selective electrode material. The results showed that the rGO/HA electrode has 4.9 times higher fluoride removal capacity than the AC electrode from a ternary solution consisting of fluoride, chloride, and nitrate ions. The fluoride removal capacity increased when the adequate voltage was applied. Furthermore, the rGO/HA electrode exhibited stability and reusability without significant capacity loss even after 50-cycle operation, maintaining about 0.21 mmol g−1 of fluoride removal capacity and approximately 96% of regeneration efficiency. Thus, this study suggests a novel electrode material for effective and selective fluoride removal in the CDI system. [ABSTRACT FROM AUTHOR]

Virus filtration in biopharmaceutical downstream process ensures viral safety with removal efficiency greater than 99.99%. Despite its robust performance, it has been reported that viruses can escape through the membrane under certain conditions. This study aimed to investigate virus breakthrough using Viresolve® Pro membrane with PP7 bacteriophage under high bacteriophage titer, high protein concentration, flow interruption, and low-flux operation. The results show high virus removal performance (LRV >6.8) up to 109 PFU/mL for 200 L/m2, with the first phage breakthrough observation over 1012 PFU/m2 of phage challenge in the membrane. As the protein concentration increased in the coexistence condition, a greater number of phages passed through the membrane. During the post-buffer flush and the operation at low filtrate flux, diffusion plays an important role in the escape of phages, which were detected as high as 1012 PFU/m2, but as low as 109 PFU/m2. These results suggest that the virus-retentive membrane may become susceptible to undesired virus breakthrough when exposed to phage challenges of > 1012 PFU/mL, providing important key factors to ensure viral safety during the downstream process of biopharmaceutical production. • Virus breakthrough during filtration was investigated under harsh conditions. • Viresolve® Pro membrane showed robust virus removal performance as LRV > 6.8. • The first phage breakthrough occurred at ∼1012 PFU/m2 of phage challenge. • As the protein concentration increased, more phages escaped. • Diffusion plays an important role in virus breakthrough. [ABSTRACT FROM AUTHOR]

Ranitidine (RNT) has been an important tertiary amine precursor of N -nitrosodimethylamine (NDMA) in chlorine-based water treatment, due to reaction with monochloramine (NH 2 Cl) with exceptionally high molar yields up to 90%. This study examined the effects of nitrite ions (NO 2 − ) on the kinetics of NDMA formation during the chloramination of RNT under variable concentrations of dissolved oxygen (DO, 0.7–7.5 mg/L), RNT (5–30 μM), NH 2 Cl (5–20 mM), NO 2 − or NO 3 − (0–2 mM) and pH (5.6–8.6). In the absence of the NO 2 − , the ultimate molar yield of NDMA after 6 h of reaction was primarily influenced by [DO] and pH, while marginally affected by initial [RNT] and [NH 2 Cl]. A kinetic model, prepared in accordance with the reaction sequence of NDMA formation, suggested that the rate determining step was accelerated with increasing [NH 2 Cl] 0 , [DO], and pH. A Kinetic study together with ultra-performance liquid chromatography-quadrupole-time of flight mass spectrometer (UPLC-Q-TOF MS) and gas chromatography (GC)/TOF MS analyses in parallel demonstrated that the nitrite ion inhibited the nucleophilic substitution of the terminal amine on NH 2 Cl, and reduced the pseudo-steady state concentration of N -peroxyl radicals, significantly decreasing the ultimate yields of NDMA. [ABSTRACT FROM AUTHOR]

Combinations of Cu(II) with hydroxylamine (HA) and hydrogen peroxide (H 2 O 2 ) (i.e., Cu(II)/HA, Cu(II)/H 2 O 2 , and Cu(II)/HA/H 2 O 2 systems) were investigated for the control of P. aeruginosa biofilms on reverse osmosis (RO) membranes. These Cu(II)-based disinfection systems effectively inactivated P. aeruginosa cells, exhibiting different behaviors depending on the state of bacterial cells (planktonic or biofilm) and the condition of biofilm growth and treatment (normal or pressurized condition). The Cu(II)/HA and Cu(II)/HA/H 2 O 2 systems were the most effective reagents for the inactivation of planktonic cells. However, these systems were not effective in inactivating cells in biofilms on the RO membranes possibly due to the interactions of Cu(I) with extracellular polymeric substances (EPS), where biofilms were grown and treated in center for disease control (CDC) reactors. Different from the results using CDC reactors, in a pressurized cross-flow RO filtration unit, the Cu(II)/HA/H 2 O 2 treatment significantly inactivated biofilm cells formed on the RO membranes, successfully recovering the permeate flux reduced by the biofouling. The pretreatment of feed solutions by Cu(II)/HA and Cu(II)/HA/H 2 O 2 systems (applied before the biofilm formation) effectively mitigated the permeate flux decline by preventing the biofilm growth on the RO membranes. [ABSTRACT FROM AUTHOR]

Semiconductor wastewater usually has a low level of dissolved oxygen and alcohol because ultra-pure water used in the process undergoes rigorous degassing and wafer development, respectively. In this study, we investigated the degradation mechanism of tetramethylammonium hydroxide (TMAH), a compound of concern in the semiconductor manufacturing process, during the UV-LED/H 2 O 2 under initial nitrogen purging conditions to remove dissolved oxygen. The effect of the initial degassing was negligible due to the in-situ O 2 production during the reaction. Along with hydroxyl radical (•OH), we first observed hydrated electron (e aq •-) formation by electron paramagnetic resonance (EPR) analysis in the presence of an excessive amount of tertiary butanol (t-BuOH), •OH scavenger, during the UV-LED/H 2 O 2 reaction. However, the contribution of e aq •- on TMAH degradation was negligible compared to •OH which played a major role in TMAH degradation. The calculated reaction rate constant of TMAH with •OH was 7.5 × 107 M−1 s−1. From competitive kinetics, [•OH] ss and k •OH, TMAH value was found to be 7.1 × 10−13 M and 7.5 × 107 M−1 s−1, respectively. The optimum pH and temperature for TMAH degradation were pH 7 and 35 °C. Three demethylated amines (trimethylamine, dimethylamine, and methylamine), along with NH 4 + and NO 3 - ions, were detected as the byproducts, implying that the main degradation mechanism of TMAH in this reaction is H abstraction by •OH-induced oxidation and hydrolysis resulting from the •OH-induced oxidation, and demethylation. Our result implies that the UV-LED/H 2 O 2 reaction can be one of the options to treat TMAH contaminated water by recycling H 2 O 2 produced in the semiconductor manufacturing process and lowering the energy consumption by using UV-LED. [Display omitted] • OH radical played a major role in the TMAH degradation in the UV-LED/H 2 O 2 reaction. • Hydrated electron (e aq •-) was observed, but the contribution can be neglected. • Neutral pH and higher temperature favored TMAH degradation. • Demethylated amines, ammonium, and nitrate were identified as major byproducts. • H abstraction by •OH oxidation and hydrolysis were the main degradation reactions. [ABSTRACT FROM AUTHOR]

Polyamide (PA) thin-film composite (TFC) membranes, fabricated by interfacial polymerization (IP) process, have been widely used for the desalination process due to high water permeability with high water/salt selectivity. A number of advanced PA TFC membranes have been developed as more efficient alternatives to further improve separation performance and address the fouling problem of commercial membranes. Here, we utilized amphiphilic functionalized cellulose nanocrystal (f-CNC) having antibacterial property as a nanofiller material for the preparation of an advanced PA membrane system, featuring improved water permeability with high salt rejection ability. This strategy is inexpensive, scalable, environmentally friendly, and practically relevant, given that typical IP process with a renewable nanofiller was employed. The amphiphilic f-CNC manipulates interfacial diffusion of monomers upon IP process, thereby decreasing the effective PA layer thickness by 30 % (from ~377 nm to ~268 nm) and increasing water permeability by 44 % (from 1.26 L m−2 h−1 bar−1 to 1.82 L m−2 h−1 bar−1). In addition, the PA membrane with f-CNC showed improved antibacterial (~90 %) and antifouling properties (~84 %, FRR) due to the specific nature of f-CNC. This study provides insights for the development of thin, effective, and antibacterial, yet more green and scalable PA membrane alternatives to the conventional desalination membranes. [Display omitted] • A new TFN membrane is prepared with amphiphilic f-CNC. • The f-CNC near the interface manipulates the monomer diffusion during IP. • Thin and asymmetric PA layer is formed through the manipulation of IP dynamics. • The water permeability of TFN membrane with f-CNC (~0.02 w/v%) increases by 44 %. • TFN membrane with f-CNC exhibits improved antibacterial and antifouling properties. [ABSTRACT FROM AUTHOR]

[Display omitted] • Zinc silicate glass powder imparts robust antimicrobial activity to polypropylene composite. • Introduction of zinc silicate glass powder effectively maintains transparency in polypropylene. • Polypropylene composite having zinc silicate glass powder exhibits excellent biocompatibility. • Nucleating effect of zinc silicate glass powder in polypropylene composite was demonstrated. • Introduction of zinc silicate glass powder enhances thermal stability and mechanical properties of polypropylene composites. Polypropylene (PP) is one of the widely utilized thermoplastics for ordinary applications, attributed to its excellent mechanical properties and resistance to heat and chemicals. However, during pandemic periods like the COVID-19 outbreak, the lack of antibacterial properties in PP might limit its usage as it does not effectively prevent bacterial adhesion and contamination. Therefore, to expand the applications of PP, it becomes crucial to impart antibacterial activity to make it a safer and more versatile material. Herein, we introduce a novel antimicrobial zinc silicate glass powder (ZS), prepared by incorporating a substantial amount of zinc oxide (35 wt%) into a silica network, as an antimicrobial filler in PP. We demonstrate that ZS significantly affects the overall performance of the PP composites, encompassing thermal properties, mechanical performances, and antimicrobial activities, while maintaining the optical transparency of PP. Notably, incorporating ZS results in a significant increase of hydrophilicity and the negative charge of the composite surface compared to the pristine PP surface, leading to the effective inhibition of microbial adhesion. This study offers valuable insights for developing antimicrobial fillers in PP composites by demonstrating the synergetic role of the physicochemical properties of ZS in imparting remarkable antibacterial activity and biocompatibility to PP. [ABSTRACT FROM AUTHOR]

In natural environments, the fate and migratory behavior of metalloid contaminants such as antimony (Sb) significantly depend on the interfacial reactivity of mineral surfaces. Although boehmite (γ-AlOOH) is widely observed in (sub)surface environments, its underlying interaction mechanism with Sb oxyanions at the molecular scale remains unclear. Considering Sb-contaminated environmental conditions in this study, we prepared boehmite under weakly acidic conditions for use in the systematic investigation of interfacial interactions with Sb(III) and Sb(V). The as-synthesized boehmite showed a nanorod morphology and comprised four crystal facets in the following order: 48.4% (010), 27.1% (101), 15.0% (001), and 9.5% (100). The combined results of spectroscopic analyses and theoretical calculations revealed that Sb(III) formed hydrogen bonding outer-sphere complexation on the (100), (010), and (001) facets and that Sb(V) preferred to form bidentate inner-sphere complexation via mononuclear edge-sharing configuration on the (100), (001), and (101) facets and binuclear corner-sharing configuration on the (010) facet. These findings indicate that the facet-mediated thermodynamic stability of the surface complexation determines the interaction affinity toward the Sb species. This work is the first to document the contribution of boehmite to (sub)surface media, improving the ability to forecast the fate and behavior of Sb oxyanions at mineral–water interfaces. [Display omitted] • Interfacial interaction between boehmite nanorods (BNRs) and Sb(III/V) was studied. • XAS and DFT analyses show a molecular-scale interaction mechanism. • Affinity of BNRs was determined by energy-based geometric structures of Sb(III/V). • The (100), (010), and (001) facets preferred to form hydrogen bonding for Sb(III). • Four facets were functional to form a bidentate inner-sphere complex for Sb(V). [ABSTRACT FROM AUTHOR]

Adsorption of per- and poly-fluoroalkyl substances (PFAS) on activated carbon (AC) is considerably hindered by the surface water constituents, degrading the ability of the AC adsorption process to remove PFAS in drinking water treatment. Herein, we developed ionic-liquid-impregnated AC (IL/AC) as an alternative to AC for PFAS sorption and demonstrated its performance with real surface water for the first time. Ionic liquids (ILs) of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (IL(C2)) and 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (IL(C6)) were selected from among 272 different ILs using the conductor-like screening model for realistic solvents (COSMO-RS) simulation. Impregnation of the ILs in AC was verified using various analytical techniques. Although the synthesized IL/ACs were less effective than pristine AC in treating PFAS in deionized water, their performances were less impacted by the surface water constituents, resulting in comparable or sometimes better performances than pristine AC for treating PFAS in surface water. The removal efficiencies of 10 wt% IL(C6)/AC for six PFAS were 1.40–1.96 times higher than those of pristine AC in a surface water sample containing 2.6 mg/L dissolved organic carbon and millimolar-level divalent cation concentration. PFAS partitioning from the surface water to ILs was not hindered by dissolved organic matter and was enhanced by the divalent cations, indicating the advantages of IL/ACs for treating significant amounts of PFAS in water. The synthesized IL/ACs were effective at treating coexisting pharmaceutical and personal-care products in surface water, showcasing their versatility for treating a broad range of water micropollutants. [Display omitted] • IL/ACs were developed for enhanced treatability of PFAS in drinking water. • One IL/AC showed up to 1.96-fold greater %removal of PFAS than AC in surface water. • PFAS partitioning from water to ILs was not inhibited by DOM and improved by Ca2+. • IL/ACs were effective for treating surface water co-contaminated by PFAS and PPCPs. [ABSTRACT FROM AUTHOR]

Highlights: [•] The oxidation of pharmaceuticals using copper-catalyzed Fenton systems was examined. [•] The rates of pharmaceutical oxidation were optimized at neutral pH values. [•] The decomposition of H2O2 and the oxidant shift explain the pH-dependence. [•] The enhanced oxidation with UV-A is explained by the role of the superoxide radical. [ABSTRACT FROM AUTHOR]

Abstract: The use of calcium oxide (CaO) demonstrates a superior potential for the activation of ground granulated blast furnace slag (GGBFS), and it produces a higher mechanical strength than calcium hydroxide [Ca(OH)2]. The mechanical strength differences between CaO- and Ca(OH)2-activated GGBFS binders are explored using isothermal calorimetry, powder X-ray diffraction, thermogravimetric and differential thermal analysis (TGA and DTA) as well as compressive strength testing. Calcium silicate hydrate (C–S–H), Ca(OH)2 and a hydrotalcite-like phase are found as reaction products in all samples. The TGA and DTA results indicate that the use of CaO produces more C–S–H, although this is not likely to be the primary cause of higher strength development in the CaO-activated GGBFS. Rather, other factors such as porosity may govern the strength at a higher order of magnitude. Significant reduction of Ca(OH)2 occurs only with the use of Ca(OH)2, followed by the formation of carbonate (CaCO3), indicating carbonation. [Copyright &y& Elsevier]

• A novel dye-sensitized oxidation system was developed by utilizing RM and PMS. • Amorphous FeO(OH)/α-Fe 2 O 3 in RM played a crucial role in the enhanced PMS activation. • Photo-sensitized AO7* enhanced the electron transfer in the FeIII/FeII cycle. • Oxidized dye and 1O 2 played an additional role in the enhanced PMS activation. • AO7/RM/PMS/vis system exhibits notable reusability and applicability in water samples. A dye-sensitized photocatalysis system was developed for degrading persistent organic contaminants using solid waste (i.e., red mud, RM) and peroxymonosulfate (PMS) under visible light. Complete degradation of acid orange 7 (AO7) was achieved in RM suspension with PMS, where the co-existence of amorphous FeO(OH)/α-Fe 2 O 3 was the key factor for PMS activation. The experimental results obtained from photochemical and electrochemical observations confirmed the enhanced PMS activation due to the Fe-OH phase in RM. DFT calculations verified the acceleration of PMS activation due to the high adsorption energy of PMS on FeO(OH) and low energy barrier for generating reactive radicals. Compared to the control experiment without AO7 showing almost no degradation of other organic contaminants (phenol, bisphenol A, 4-chlorophenol, 4-nitrophenol, and benzoic acid), photo-sensitized AO7* enhanced electron transfer in the FeIII/FeII cycle, dramatically enhancing the degradation of organic contaminants via radical (•OH, SO 4 •−, and O 2 •−) and non-radical (dye*+ and 1O 2) pathways. Therefore, the novel finding of this study can provide new insights for unique PMS activation by heterogeneous Fe(III) containing solid wastes and highlight the importance of sensitized dye on the interaction of PMS with Fe charge carrier for the photo-oxidation of organic contaminants under visible light. [Display omitted] [ABSTRACT FROM AUTHOR]

Despite the great potential of electrochemical nitrate reduction as a hydroxylamine production method, this strategy has not been sufficiently examined, and the effects of electrode material type on the selectivity and efficiency of this reduction remain underexplored. To bridge this gap, the present study evaluated six metals (Ag, Cu, Ni, Sn, Ti, and Zn) as cathode materials for the electrochemical reduction of nitrate to hydroxylamine, showing that the selectivity of hydroxylamine production was maximal for Sn, while the corresponding faradaic and energy utilization efficiencies were maximal for Ti. Although all tested materials favored nitrate reduction over hydrogen evolution, the disparity in the onset potentials of these reactions did not adequately explain the variations in nitrate removal efficiency, which was found to be influenced by material resistance and charge-transfer properties. The rate constants of elementary nitrate reduction steps determined from the time-dependent concentrations of nitrate and its reduction products (nitrous acid, hydroxylamine, and ammonium) were used to calculate the selectivity and efficiency of hydroxylamine production for each electrode. In turn, these selectivities and efficiencies were correlated with the density functional theory–computed adsorption energies of a key hydroxylamine precursor on different electrodes to afford a volcano-type plot with Ti and Sn at its pinnacle. Thus, this study introduces valuable descriptors and methods for the further screening of electrocatalysts for hydroxylamine generation and the establishment of more environmentally friendly hydroxylamine production techniques utilizing sustainable electricity. [Display omitted] • Hydroxylamine (HA) was produced through electrochemical nitrate reduction • Ag, Cu, Ni, Sn, Ti, & Zn cathodes were evaluated for electrochemical HA production • Sn and Ti demonstrated highest HA production selectivity & efficiency, respectively • Rates of individual nitrate reduction steps were determined using kinetic modeling • DFT calculations found optimal adsorption energies of the HA precursor state [ABSTRACT FROM AUTHOR]

Biodegradable cellulose acetate (CA) nanofibers containing Rose Bengal (RB) dye were fabricated by electrospinning technique. RB dye, an anionic photosensitizer, has been used in photodynamic therapy due to its excellent biocompatibility and ability to absorb light to generate reactive oxygen species (ROS), but has a decisive disadvantage of water solubility on infection prevention. Firstly, water-insoluble RB dye was synthesized through complexation with cationic ionic liquid (IL) for antiviral agents. The synthesized water-insoluble RB dyes were embedded into biodegradable CA nanofibers by electrospinning. The electrospun nanofibers passed both antiviral test for φx174 virus under visible light irradiation and biodegradability-test using enzymes. The fabricated RB nanofibers absorbed light and generated ROS to inactivate the virus. As a result, the log reduction (-Log 10 (N/N 0)) of φx174 titer under visible light reached a detection limit of 5.00 within 30 min. Also, the fabricated nanofibers were degraded up to 34 wt % in 9 weeks by lipase and cellulase enzymes compared with non-biodegradable nanofibers. [Display omitted] • Antiviral nanofiber mats were fabricated using biodegradable CA and photosensitive RB dyes by electrospinning technique. • Only green solvents such as ethyl lactate and ethanol were used to prepare electrospinning solution instead of harmful organic solvents. • Anionic RB dye was converted into water-insoluble by complexing with cationic IL. • Nanofibers yielded more than 5 in the log reduction of φx174 titer under visible light irradiation within 30 min. • Nanofibers were degraded up to 34 wt % in 9 weeks by lipase and cellulase enzymes. [ABSTRACT FROM AUTHOR]

Abstract: The photocatalytic activity of a brick grain-supported iron oxide (denoted as B1) was tested for its activity to degrade Reactive Black 5 (RB5) in the presence of oxalic acid. B1 was obtained as a solid waste from a wastewater treatment plant, and characterized using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray powder diffraction (XRD) and N2 adsorption/desorption isotherm analyses. The decolorization experiments were performed in a fluidized bed reactor with aeration under UV-A irradiation (λ =365nm). The effects of various factors such as solution pH, concentration of oxalic acid and dissolved oxygen on the decolorization of RB5 were evaluated considering the contributions of adsorption and photo-catalytic degradation. The role of dissolved iron in the removal of RB5 and the stability of B1 were also examined. In addition, the removal of TOC during the photo-catalytic reaction was monitored. [Copyright &y& Elsevier]

The influence of various reaction parameters on herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) removal were examined in the photo/ferrioxalate/H2O2 system, with regard to: (1) sulfate, phosphate, and ⋅OH scavenger, as solution constituent; and (2) light intensity, ferrioxalate, H2O2, and oxalate concentration, as operating parameter. In terms of 2,4-D removal, the photo/ferrioxalate/H2O2 system has always been superior to the photo/Ferric ion/H2O2 system, despite the high presence of anions (sulfate 100 mM, phosphate 1 mM) or ⋅OH scavenger. Not only the rate of 2,4-D removal, but also the decomposition rate of H2O2 and oxalate proportionally increase with light intensity. The ferrioxalate concentration determines the light absorption fraction, and thus, controls the rates of 2,4-D removal, and the decomposition of H2O2 and oxalate, are predicted from kinetic formulations. The optimal concentration of H2O2 and oxalate, according to the extent of the ⋅OH scavenging reaction with these reagents, has been demonstrated for 2,4-D removal. It was found that an increasing oxalate concentration, which bears the burden of increased dissolved organic carbon (DOC), does not occur. This is because its decomposition, as a result of the photochemical reduction of the ferric oxalate complex, results in a decrease of the equivalent DOC. The importance of the key reaction factors to be considered, when applying this system to real wastewater treatment, is also discussed. [Copyright &y& Elsevier]

• The oxidative performance of the bl-TNAs/PEC system was enhanced by PS. • Adding persulfate led to a high yield of •OH and the generation of SO4•−. • System showed highly stable performance under broad pH range and water matrix. • Degradation of multiple pollutants occurred in the order BPA > 4-CP > SMX > CBZ. This study investigated the influence of adding peroxydisulfate (PDS) to a photoelectrocatalysis (PEC) system using self-doped TiO 2 nanotube arrays (bl-TNAs) for organic pollutant degradation. The addition of 1.0 mM PDS increased the bisphenol-A (BPA) removal efficiency of PEC (PEC/PDS) from 65.0% to 85.9% within 1 h. The enhancement could be attributed to the high formation yield of hydroxyl radicals (·OH), increased charge separation, and assistance of the sulfate radicals (SO 4 ·−). The PDS concentration and applied potential bias were influential operating parameters for the PEC/PDS system. In addition, the system exhibited a highly stable performance over a wide range of pH values and background inorganic and organic constituents, such as chloride ions, bicarbonate, and humic acid. Further, the degradation performance of the organic pollutant mixture, including BPA, 4-chlorophenol (4-CP), sulfamethoxazole (SMX), and carbamazepine (CBZ), was evaluated in 0.1 M (NH 4) 2 SO 4 solution and real surface water. The degradation efficiency increased in the order of CBZ < SMX < 4-CP < BPA in the PEC and PEC/PDS systems with both water matrices. Compared with the PEC system, the PEC/PDS (1.0 mM) system showed a threefold higher pseudo first-order reaction rate constant for BPA among pollutant mixtures in surface water. This was attributed to enhanced ·OH production and the selective nature of SO 4 ·−. The pseudo first-order reaction rate constants of other pollutants, i.e., 4-CP, SMX, and CBZ increased ca. twofold in the PEC/PDS system. The results of this study showed that the PEC/PDS system with bl-TNAs is a viable technology for oxidative treatment. Image, graphical abstract [ABSTRACT FROM AUTHOR]

• C 60 -ND clusters were produced by simple hand-grinding of C 60 and NDs. • C 60 -ND showed enhancement in water dispersibility and photosensitized ROS yield. • C 60 -ND effectively oxidized organic contaminants under visible light illumination. • The photochemical reactions of ND-C 60 induced cancer cell apoptosis. The unique capability of fullerene (C 60) to absorb light and generate reactive oxygen species (ROS) has been extensively studied for photosensitized water treatment and cancer therapy. Various material synthesis strategies have been proposed in parallel to overcome its intrinsic hydrophobicity and to enhance availability in water and physiological media. We present here a strikingly simple approach to make C 60 available to these applications by hand-grinding dry C 60 powder with nanodiamond (ND) using a mortar and pestle. The resulting ND-C 60 composite was found to form a stable aqueous colloidal suspension and efficiently drive photosensitized production of ROS under visible light illumination. ND-C 60 rapidly adsorbed and oxidized organic contaminants by photogenerated ROS. In the experiments for photodynamic cancer therapy, ND-C 60 was internalized by cancer cells and induced cell apoptosis without noticeable toxicity. Treatment of tumor-bearing mice with ND-C 60 and light irradiation resulted in tumor shrinkage and prolonged survival time. [ABSTRACT FROM AUTHOR]

In this study, we first comprehensively studied peroxymonosulfate (PMS) and peroxydisulfate (PDS) activation mechanisms using N, O codoped sludge biochar (NOSB) to degrade organics from water. Among the catalysts, NOSB with a higher content of graphitic N, optimal edge nitrogen (pyridinic N and pyrrolic N), C O groups, sp2-hybridized C, and rich defects were demonstrated to be a superior catalyst. Therefore, by activating PDS and PMS, NOSB exhibited the highest rate of BPA degradation, which was 22-fold and 13-fold that of pristine sludge biochar, respectively. However, owing to different oxidation potentials and molecular structures, PMS and PDS show different degradation performances due to various catalytic mechanisms occurring, even with the same biochar. Due to the asymmetrical structure of PMS, electrons passed from PMS to NOSB and further generated singlet oxygen (1O 2), which governs the degradation of bisphenol A with an auxiliary contribution of single electron transfer. Meanwhile, PDS is reduced at the Lewis basic sites of NOSB, forming inner-surface-bound {PDS-NOSB}, which was oxidizing around neighboring carbon and decomposed targets through transferring single and double electrons. NOSB is promising for practical applications because of its adaptation to a wide pH range, anions, high total organic carbon removal, tunable active sites, and re-usability for degrading organics via PMS/PDS activation. This study unveils knowledge about N, O codoped sludge biochar catalysts for activating PMS/PDS and advocates a great approach for organics' degradation in the environment. [Display omitted] • N-doped O-rich biochar was prepared using wet sludge and dicyandiamide. • N and O codoping create five reactive sites simultaneously, making biochar a unique catalyst for PMS/PDS. • PMS activation occurred at Lewis-acid sites and generated dominant ROS 1O 2. • PDS activation occurred at Lewis-basic sites and generated inner-sphere-bound complexes. [ABSTRACT FROM AUTHOR]

Phosphate removal is a critical issue in water treatment because excess levels of phosphate can cause severe eutrophication. Capacitive deionization (CDI), which has several advantages, such as simple, eco-friendly, and energy efficient operations, has gained attention as a potential alternative over conventional phosphate removal technologies like activated sludge, chemical precipitation, and adsorption processes. However, CDI suffers from a lack of selectivity for phosphate, resulting from non-selective anion removal of positively biased electrodes. Herein, the layered double hydroxide/reduced graphene oxide (LDH/rGO) composite electrode in the CDI process was examined for selective phosphate removal. LDH/rGO showed the selective phosphate removal performance with sustained phosphate removal efficiency even in the presence of excess chloride. In addition, the selective phosphate removal in the CDI process with the LDH/rGO was successfully demonstrated in the simulated water, fabricated by adding a significantly low concentration of phosphate (0.4 mg∙L−1) into real river water matrix (Han River, Seoul, Korea). This result was explained by the high electrochemical selectivity of the LDH/rGO for phosphate. [ABSTRACT FROM AUTHOR]

• Sulfate oxidation on BDD anodes causes sulfate radical and persulfate formation. • Anodically produced persulfate is activated via one-electron reduction on cathodes. • Anodic persulfate formation and resistive heating lead to sulfate radical generation. • Combination with UV photolysis transforms residual persulfate into sulfate radical. • Interconversion between sulfate and persulfate hinders oxyanion accumulation. This study scrutinized the roles of sulfate radicals (SO 4 −) and peroxydisulfate (PDS) formed from SO 4 2− in electrochemical organic oxidation on a boron-doped diamond (BDD) electrode. The substrate-specific performance of electrochemical oxidation using SO 4 2− as the electrolyte aligned with the reactivity of SO 4 − produced via radiolysis- or heat-induced PDS activation, but was distinct from the non-selective oxidation efficiency observed in an aqueous ClO 4 − solution. A comparison of the treatment efficiencies using different electrolytes (i.e., Cl−, SO 4 2−, and ClO 4 −) showed no pronounced enhancing effect of SO 4 − on the anodic oxidation of diverse organics (except perfluorooctanoate), which implied that direct electron transfer and hydroxyl radical-induced oxidation proceeded as complementary reaction routes. Repeated electrolytic oxidation caused substantial electrolyte exchange from Cl− to ClO 4 −, which retarded organic oxidation accompanied by ClO 4 − accumulation. Conversely, high-yield PDS production observed when SO 4 2− was used instead barely reduced treatment efficiency. Together with SO 4 − detection in the electron paramagnetic resonance spectrum, a correlation between 4-chlorophenol oxidation rate and the faradaic efficiency for SO 4 2− formation, monitored in PDS solutions while varying the cathode material, suggested cathodic PDS activation. The electrocatalytic performance was demonstrated to be further improved with anodically formed PDS activation through naturally occurring resistive heating or combination with UV photolysis as a post-treatment step. [ABSTRACT FROM AUTHOR]

Owing to the surge in plastic waste generated during the COVID-19 pandemic, concerns regarding microplastic pollution in aqueous environments are increasing. Since microplastics (MPs) are broken down into submicron (< 1 µm) and nanoscale plastics, their real-time morphological detection in water is necessary. However, the decrease in the scattering cross-section of MPs in aqueous media precludes morphological detection by bright-field microscopy. To address this problem, we propose and demonstrate a differential interference contrast (DIC) system that incorporates a magnification-enhancing system to detect MPs in aqueous samples. To detect MPs in both the stationary and mobile phases, a microfluidic chip was designed, taking into consideration the imaging depth of focus and flow resistance. MPs of various sizes flowing in deionized, tap, and pond water at varying speeds were observed under Static and Flow conditions. Successful real-time morphological detection and quantification of polystyrene beads down to 200 nm at a constant flow rate in water were achieved. Thus, the proposed novel method can significantly reduce analysis time and improve the size-detection limit. The proposed DIC microscopy system can be coupled with Raman or infrared spectroscopy in future studies for chemical composition analysis. Microplastics (MPs), particularly submicron plastics < 1-µm, can pose a risk to human health and aquatic ecosystems. Existing methods for detecting MPs in the aqueous phase have several limitations, including the use of expensive instruments and prolonged and labor-intensive procedures. Our results clearly demonstrated that a new low-cost flow-channeled differential interference contrast microscopy enables the real-time morphological detection and quantification of MPs down to 200 nm under flowing conditions without sample labeling. Consequently, our proposed rapid method for accurate quantitative measurements can serve as a valuable reference for detecting submicron plastics in water samples. [Display omitted] • Differential interference contrast (DIC) microscopy was used to detect microplastic. • The flow-channeled DIC system was combined with a microfluidic chip. • The DIC system successfully visualized submicron plastics down to 200 nm in water. • Real-time detection was successful in the mobile phase without labeling. • High quantitative accuracy was attained under static and flowing conditions. [ABSTRACT FROM AUTHOR]

• Chemical disinfectants inactivated and lysed C. polykrikoides in seawater. • Cell inactivation efficacy followed the order O 3 > MnO 4 − > NaOCl > H 2 O 2. • Secondary oxidants produced by O 3 and NaOCl contributed to cell removal. • H 2 O 2 is a suitable disinfectant for field applications with minimal toxicity to fish. For decades, red tide control has been recognized as necessary for mitigating financial damage to fish farms. Chemical disinfectants, frequently used for water disinfection, can reduce the risk of red tides on inland fish farms. This study systematically evaluated four different chemical disinfectants (ozone (O 3), permanganate (MnO 4 −), sodium hypochlorite (NaOCl), and hydrogen peroxide (H 2 O 2)) for their potential use in inland fish farms to control red tides by investigating their (i) inactivation efficacy regarding C. polykrikoides , (ii) total residual oxidant and byproduct formation, and (iii) toxicity to fish. The inactivation efficacy of C. polykrikoides cells by chemical disinfectants from highest to lowest followed the order of O 3 > MnO 4 − > NaOCl > H 2 O 2 for different cell density conditions and disinfectant doses. The O 3 and NaOCl treatments generated bromate as an oxidation byproduct by reacting with bromide ions in seawater. The acute toxicity tests of the disinfectants for juvenile red sea bream (Pagrus major) showed that 72-h LC 50 values were 1.35 (estimated), 0.39, 1.32, and 102.61 mg/L for O 3 , MnO 4 −, NaOCl, and H 2 O 2 , respectively. Considering the inactivation efficacy, exposure time of residual oxidants, byproduct formation, and toxicity toward fish, H 2 O 2 is suggested as the most practical disinfectant for controlling red tides in inland fish farms. [Display omitted] [ABSTRACT FROM AUTHOR]

• pH-swing chlorination from acidic to neutral conditions effectively degraded urea. • Urea degradation was accelerated with increasing the second-stage pH. • Deprotonation of chloroureas is responsible for the accelerated urea degradation. • pH-swing chlorination successfully reduced total nitrogen during urea degradation. Urea reacts with chlorine to form chlorinated ureas (chloroureas), and fully chlorinated urea (tetrachlorourea) is further hydrolyzed into CO 2 and chloramines. This study found that the oxidative degradation of urea by chlorination was enhanced by the pH swing, wherein the reaction proceeded under an acidic pH (e.g., pH = 3) in the first stage, and the solution pH was subsequently increased to a neutral or alkaline value (e.g., pH > 7) in the second-stage reaction. The degradation rate of urea by pH-swing chlorination increased with increasing chlorine dose and pH during the second-stage reaction. The pH-swing chlorination was based on the opposite pH dependence of sub-processes comprising urea chlorination. The formation of monochlorourea was favored under acidic pH conditions; however, the subsequent conversion into di- and trichloroureas was favored under neutral or alkaline pH conditions. The deprotonation of monochlorourea (pK a = 9.7 ± 1.1) and dichlorourea (pK a = 5.1 ± 1.4) was suggested to be responsible for the accelerated reaction in the second stage under increased pH conditions. pH-swing chlorination was also effective in degrading urea at low concentrations (micromolar levels). In addition, the total nitrogen concentration significantly decreased during the degradation of urea because of the volatilization of chloramines and the release of other gaseous nitrogen compounds. [Display omitted] [ABSTRACT FROM AUTHOR]

In this study, we explored the correlation between the catalytic activity of UK Biochar Research Center biochars (BCs) and their physicochemical properties, suggesting a potential role of endogenous iron in promoting their persulfate activation capability by heat treatment. A steady improvement in the persulfate activation efficiency with increasing annealing temperature was observed exclusively for iron-containing BCs (e.g., sewage sludge (SS) BCs). Along with increasing the Brunauer–Emmett–Teller surface area, thermal annealing formed carbon-wrapped iron particles on the SS BC surfaces, produced crystalline elemental iron and iron carbides, and caused an sp 3 -to-s p 2 conversion in the carbon phase. Comparing the annealed SS BCs in terms of the open circuit potential shift, electrical conductivity, and thermodynamic binding parameters showed that the heat-initiated modification enhanced the electron transfer-mediating capacity and surface affinity toward persulfate, which led to the beneficial effect of annealing on the carbocatalytic activity of iron-containing BCs for non-radical persulfate activation. [Display omitted] • UKBRC standard biochars were assessed in terms of persulfate activation capability. • Enhancing effect of thermal annealing was unique to iron-containing biochars. • Heat-induced iron-carbon interaction produced elemental iron and iron carbides. • Endogenous iron catalyzed carbon phase transformation during thermal annealing. • Thermal modification improved electrical conductivity and binding affinity. [ABSTRACT FROM AUTHOR]

Abstract ZSM-5 zeolite beads (ZB) modified with lanthanum (La) were prepared by impregnating ZB in a lanthanum nitrate solution (denoted as La-ZB). La-ZB was characterized via SEM, BET, ICP-OES and XRD techniques, which confirmed the doping of La on the surface of the ZB. The surface area and pore volume of La-ZB decreased marginally after the La-modification due to a partial pore blockage by the La dopant. La-ZB showed an improved phosphate adsorption compared to ZB, and the maximum phosphate adsorption capacities by ZB and La-ZB (determined by Langmuir isotherm) were 59.8 and 106.2 mg/g, respectively. Moreover, the adsorption kinetics proceeded according to the mechanism of the pseudo-second-order model. The phosphate adsorption by La-ZB exhibited an optimum at pH 6. In regeneration process of phosphate-loaded La-ZB, five times adsorption-desorption cycles were applied and 81.8% phosphate was recovery. In a test using wastewater containing a high phosphate concentration (218.6 mg/L), La-ZB exhibited 96.8% phosphate removal, which is 1.8 times higher than that of ZB (53.5%). The results indicate that La-ZB can be a promising recyclable adsorbent for the removal and recovery of phosphate from wastewater. Graphical abstract Image 1 Highlights • La-ZB is an effective adsorbent for removal and recovery of phosphate in wastewater. • La-ZB was superior in phosphate adsorption to other La-modified adsorbents. • 81.8% phosphate was recovery even after 5 times adsorption-desorption cycles. [ABSTRACT FROM AUTHOR]

Changes in surface carbon hybridization through high-temperature annealing (>1000 °C) of nanodiamond (ND), i.e., surface graphitization, enable peroxymonosulfate (PMS) activation by ND. Alternatively, this study suggests low-temperature surface modification (500 °C) of ND as an effective strategy for allowing ND to activate PMS. ND calcination in the presence of poly(diallydimethylammonium chloride) (PDDA) and graphene oxide (GO) in an NH 3 atmosphere produced binary and ternary nitrogen-doped ND composites (i.e., N-ND/PDDA and N-ND/PDDA/GO). Compared with bare ND, theses surface-modified NDs markedly enhanced organic oxidation associated with PMS activation. In particular, N-ND/PDDA/GO outperformed graphitized ND in terms of PMS activation capacity. Spectroscopic characterization implied that the content of pyridinic N and the N doping level increased with further modification of ND. Oxidation by PMS activated with ND-based materials did not involve radical attack, as methanol did not exhibit a quenching effect, formaldehyde yield was insignificant, conversion of bromide into bromate was negligible, the substrate specificity contradicted sulfate radical (SO 4 − ) reactivity, and no electron paramagnetic resonance spectral features were assignable to SO 4 − adducts. Impedance spectroscopic analysis indicated a high correlation between PMS activation efficacy and electrical conductivity. Chronoamperometric measurements showed that sequential injection of PMS and 4-chlorophenol caused current generation at electrodes coated with ND-based activators, and the increase in current intensity correlated well with PMS activation capacity. These findings suggest that ND-derived materials facilitated the electron transfer from organics to PMS, resulting in a degradative reaction route not reliant on radical species. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • TiO 2 nanoparticles were immobilized on steel mesh without polymer binder. • Immobilization was performed by electrospraying and hot-pressing treatment. • The immobilized photocatalyst was effective in the removal of pharmaceuticals. • It also exhibited excellent disinfection activity against E.coli and MS2 phage. Abstract An immobilized photocatalyst was prepared by thermally treating TiO 2 -coated steel mesh (TiO 2 -IS) in a laboratory hot-press with no binder. TiO 2 coating was performed by electrospraying a 1 mg/mL methanol dispersion of Evonik P25 powder. The thermal treatment conditions at 350 °C, 100 Mpa, and 1 h were found to be the optimum conditions. Scanning electron microscopic images displayed a robust and adherent TiO 2 layer on steel mesh. X-ray photoelectron spectroscopy and elemental mapping studies confirmed that the Fe 3 O 4 interface formed during thermal treatment strongly bound the TiO 2 on steel mesh. The XRD patterns of TiO 2 -IS indicated the preservation of crystalline structure of Evonik P25 (anatase and rutile mixture) and the existence of iron oxide interface. Under UVA irradiation, 10 μM of methylene blue was completely decolorized within 40 min using an immobilized photocatalyst with 2.120 mg of TiO 2 per 2.5 × 5.0 cm2 and showed stable efficacy in 25 consecutive photocatalytic runs. Furthermore, this sample degraded the organic micropollutants (e.g., pharmaceuticals) such as carbamazepine, ranitidine, acetaminophen, and trimethoprim at the rates of 0.041, 0.165, 0.089, and 0.079 min−1, respectively. Under UVA irradiation, it exhibited high photocatalytic disinfection activity for Escherichia coli and MS2 coliphage. [ABSTRACT FROM AUTHOR]

Ozonation, a viable option for improving wastewater effluent quality, requires process optimization to ensure the organic micropollutants (OMPs) elimination and disinfection under minimized byproduct formation. This study assessed and compared the efficiencies of ozonation (O 3) and ozone with hydrogen peroxide (O 3 /H 2 O 2) for 70 OMPs elimination, inactivation of three bacteria and three viruses, and formation of bromate and biodegradable organics during the bench-scale O 3 and O 3 /H 2 O 2 treatment of municipal wastewater effluent. 39 OMPs were fully eliminated, and 22 OMPs were considerably eliminated (54 ± 14%) at an ozone dosage of 0.5 gO 3 /gDOC for their high reactivity to ozone or •OH. The chemical kinetics approach accurately predicted the OMP elimination levels based on the rate constants and exposures of ozone and •OH, where the quantum chemical calculation and group contribution method successfully predicted the ozone and •OH rate constants, respectively. Microbial inactivation levels increased with increasing ozone dosage up to ∼3.1 (bacteria) and ∼2.6 (virus) log 10 reductions at 0.7 gO 3 /gDOC. O 3 /H 2 O 2 minimized bromate formation but significantly decreased bacteria/virus inactivation, whereas its impact on OMP elimination was insignificant. Ozonation produced biodegradable organics that were removed by a post-biodegradation treatment, achieving up to 24% DOM mineralization. These results can be useful for optimizing O 3 and O 3 /H 2 O 2 processes for enhanced wastewater treatment. [Display omitted] • 70 OMPs and 6 bacteria/viruses in sewage effluent were treated by O 3 and O 3 /H 2 O 2. • 33 k O3 and 23 k •OH were newly reported, calculated from QSAR and GCM. • Good prediction of OMP removals using O 3 /•OH reactivity and exposure. • The microbial inactivation was lower than the linear kinetic model prediction. • O 3 /H 2 O 2 minimized bromate formation but decreased microbial inactivation than O 3. [ABSTRACT FROM AUTHOR]