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The superabsorbents' application as materials for the preparation of modern mineral fertilizers of controlled activity is presented. Under the static conditions, the commercial acrylic-based Agro® Hydrogel was used as a sorbent for Cu(II), Fe(III), Mn(II), and Zn(II) ions in the presence of three biodegradable complexing agents of the new generation: (N-1,2-dicarboxyethyl)-D,L-aspartate acid (IDHA), N,N-ethylenediaminedisuccinic acid (EDDS) and N,N-bis(carboxymethyl) glutamic acid (GLDA). The ions and complexes concentrations were determined by the inductively coupled plasma optical emission spectrometer (ICP-OES). The characterization of hydrogel before and after the adsorption process was made using the Fourier transform infrared spectroscopy (FT-IR), surface area determination (ASAP), scanning electron microscopy (SEM-EDS) as well as the thermogravimetric (TGA) methods. The influence of the phase contact time, initial concentration, and pH on the adsorption capacities was investigated. The kinetic and adsorption parameters were determined. The Langmuir, Freundlich, Dubinin–Radushkevich, and Temkin adsorption models were applied to describe the experimental data. The Langmuir isotherm model accurately characterized the equilibrium process. The adsorption process was fast, and it reached equilibrium after 60 min of the phase contact time. The research on the adsorption of Cu(II), Fe(III), Mn(II), and Zn(II) onto Agro® Hydrogel with IDHA, EDDS, and GLDA indicates that these complexing agents improve process efficiency. [ABSTRACT FROM AUTHOR]

Presently, it is a great challenge to maintain high catalytic reactivity and recycling performance of zero-valent iron (ZVI) for rapid degradation of refractory combined pollutants possessing electron withdrawing groups and electron-donating groups, simultaneously. The state-of-the-art ZVI technique aims to enhance the generation of reactive oxygen species (ROSs) and H 2 with the construction of novel noble metals-decorated ZVI-based tri(bi)metal. Herein, we selected the precursors of Cu(NO 3) 2 and KPdCl 6 to synthesize sponge iron (s-Fe0)-based trimetal via interfacial displacement reactions and further disclosed the main influencing factors for detailed evaluation of ideal trimetal. The results show that the preferred palladised copper-decorated s-Fe0 (0.025 wt %Pd-(5 wt %Cu-s-Fe0)) with 30 g/L input dosage could achieve ∼ 90% removal of 20 mg/L rhodamine B (RhB) within four recycling tests. The aeration process over trimetal (Pd-(Cu-s-Fe0)/O 2) as well as the addition of H 2 O 2 (Pd-(Cu-s-Fe0)/H 2 O 2) further achieves high catalytic reactivity and recycling performance. Moreover, Pd-(Cu-s-Fe0) could effectively degrade a series of combined pollutants including RhB + triclosan and RhB + tetrabromobisphenol A (TBBPA), respectively. Furthermore, the interfacial nanostructures of Pd–Cu covering the surface of trimetal have been characterized and the variations of ROS have been recorded with electron spin resonance (ESR) signals. Additionally, the bicatalytic mechanism over Pd-(Cu-s-Fe0) has been explored. Accordingly, the simultaneous generation of ROSs and H 2 over Pd-(Cu-s-Fe0) highlights the significant potential for rapid degradation of a series of refractory combined pollutants. [Display omitted] • Pd-(Cu-s-Fe0) with precursors of Cu(NO 3) 2 possesses excellent cycling performance. • Reactive oxygen species (ROSs) and hydrogen atoms (H*) were simultaneously produced. • ROSs and H* are essential for degradation of refractory RhB and its products, respectively. • Trimetal rapidly degrades a variety of combined pollutants via the role of ROSs and H*. [ABSTRACT FROM AUTHOR]

[Display omitted] • The types and stability constants of REE complexes with IDHA were determined. • Twelve common ion exchangers were analysed for the REE-IDHA complexes adsorption. • Physicochemical analysis of the ion exchangers was made by SEM, XPS, and FTIR methods. • A high sorption efficiency of REE with the biodegradable IDHA was obtained. • Comprehensive process optimization using static and dynamic methods was performed. Environmental pollution and the continued depletion of many deposits have made the recycling of used materials an urgent need. An important aspect of this topic is the development of alternative compounds with a more favourable environmental profile compared to those currently in use. Indeed, when designing such processes, the negative human impact on the environment should be mitigated as much as possible. This paper presents the results of a study on the application of biodegradable complexing agent iminodisuccinic acid (IDHA) for the recovery of La(III), Nd(III) and Ho(III) by adsorption (single-component systems, static and dynamic methods) using various types of ion exchangers. The results obtained allow to determine the optimal process conditions and show that the chelating ion exchanger Purolite S957 has the highest adsorption capacity related to the La(III) complexes (142.29 mg/g), while the Nd(III) and Ho(III) complexes adsorb with the highest efficiency (161.04 mg/g for Nd(III) and 201.74 mg/g for Ho(III)) in the cation exchanger Lewatit SP112. According to the desorption studies the adsorbents are characterized by a large regeneration capability. This paper also presents the characterization of the physicochemical properties of the applied ion exchangers and the analysis of the binary systems (Ln(III)-IDHA) to determine the overall stability constants of the complexes using the potentiometric methods. Biodegradable IDHA was used to this aim. [ABSTRACT FROM AUTHOR]

In this study, we firstly develop the photo-Fenton-like system with millimetric sponge iron (s-Fe 0 ), H 2 O 2 , visible light (vis, λ ≥ 420 nm) and rhodamine B (RhB), and present a comprehensive study concerning the mechanism. Thus, we investigate (1) the adsorption of RhB onto s-Fe 0 , (2) the photo-Fenton-like removal of RhB over iron oxides generated from the corrosion of s-Fe 0 , (3) the homogeneous photo-Fenton removal of RhB over Fe 2+ or Fe 3+ , (4) the Fe 3+ -RhB complexes, and (5) the photo-Fenton-like removal of tetrabromobisphenol A (TBBPA). The results show that neither the adsorption process over s-Fe 0 nor the photo-Fenton-like process over FeOOH, Fe 3 O 4 and Fe 2 O 3 , achieved efficient removal of RhB. For comparison, in homogeneous photo-Fenton process, the presence of Fe 3+ ions, rather than Fe 2+ ions, effectively eliminated RhB. Furthermore, the UV–vis spectra showing new absorbance at ∼ 285 nm indicate the complexes of RhB and Fe 3+ ions, adopting vis photons to form excited state and further eject one electron via ligand-to-metal charge-transfer to activate H 2 O 2 . Additionally, efficient TBBPA removal was obtained only in the presence of RhB. Accordingly, the s-Fe 0 – based photo-Fenton-like process assisted with dyestuff wastewater is promising for removing a series of persistent organic pollutants. [ABSTRACT FROM AUTHOR]

The microwave-induced catalytic oxidation (MICO) process has demonstrated promise for the treatment of dye contaminants in water but its mechanism has not been fully elucidated so far. In this study, NiFe 2 O 4 catalysts were synthesized using sol-gel and chemical co-precipitation (cp) methods and applied to decolorizing a series of pollutants in a MICO process. NiFe 2 O 4 (cp) calcined at 100 °C or 300 °C decolorized over 60% of brilliant green (BG) in 10 min, but the decolorization efficiency decreased quickly when the catalyst was reused. NiFe 2 O 4 (sol-gel), however, did not achieve any significant removal of BG. Moreover, the solution pH rose to 8.6 when suspensions containing NiFe 2 O 4 (cp-100 °C) were irradiated with microwave (MW) energy. Control experiments show that addition of NaOH achieved efficient decolorization of aqueous BG solution. This indicates that MW irradiation may promote the release of OH − residues and enhance the removal of dyes. Furthermore, in suspensions containing organic polydimethyl siloxane fluid and NiFe 2 O 4 (100 °C), the MW energy distribution could be greatly changed, accompanying with quick increase of temperature. Variations of XRD patterns for NiFe 2 O 4 (100 °C), however, were not observed, even if suspensions contained carborundum (SiC). This indicates that so-called hot-spots and reactive oxygen species could be hardly formed in suspensions containing inorganic solvent H 2 O. [ABSTRACT FROM AUTHOR]

To enhance the dechlorination reactivity of millimetric sponge iron (s-Fe 0 ), a facile one-pot method was used to decorate s-Fe 0 with Ag + ions under ambient conditions. The results recorded by X-ray diffraction patterns, X-ray photoelectron spectra and high-resolution transmission electron microscopy demonstrated that the growth of Ag 0 was dominated primarily by (1 1 1) plane with a mean length of ∼20 nm. The roles of Ag 0 loading, catalyst dosage, particle size, initial pH and contaminant concentration were assessed during the removal of pentachlorophenol (PCP). Catalyst recyclability was also studied. The results revealed that 3–5 mm s-Fe 0 particles with 5 wt% Ag 0 loading exhibited the best performance with a dose of 3.0 g per 60 mL PCP solution. In addition, the dechlorination of PCP followed two-step, pseudo-first-order reaction kinetics, and Ag 0 -s-Fe 0 was advantageous compared with bimetals of nanoscale zero-valent iron, iron power and iron flakes. The dechlorination mechanism of PCP over Ag 0 -s-Fe 0 was attributed to the surface Ag 0 decoration, which catalyzed the formation of reactive hydrogen atoms for indirect reaction, and the direct electron transfer via Fe–Ag 0 galvanic cells for direct reaction. This suggests that Ag-based bimetals of s-Fe 0 have great potential in the pretreatment of organic halogen compounds in aqueous solution. [ABSTRACT FROM AUTHOR]

[Display omitted] • A single-mode microwave combustion process (MCP) anneals sol–gel precursors of ZnFe 2 O 4. • Primary parameters of MCP for synthesis of ZnO@ZnFe 2 O 4 have been determined. • Negatively charged ZnO@ZnFe 2 O 4 achieves photosensitization degradation of cationic dyes. • Lifetime of electron/hole carriers in ZnO@ZnFe 2 O 4 has been effectively prolonged. • A single-mode MCP endows P25 TiO 2 with visible light-driven activation for the degradation of estradiol. To date, the inferior physicochemical properties of nanomaterials synthesized with a household microwave (MW) oven have been attributed to a large extent to the non-uniform electromagnetic field. Herein, we developed a single-mode MW combustion process (MCP) considering criteria of green chemistry and further annealled the amorphous ZnFe 2 O 4 -based sol–gel precursors. The preferred single-mode MCP-based parameters mainly include 7 g : 2 g of the mass ratio (w/w) of SiC : sol–gel precursors, 1 : 1.5 of initial molar ratio of citric acid : metal ions (CA : M), 300 ℃ ∼ 600 ℃ range of the calcination temperature, N 2 atmosphere of 3 L/min as well as the washing pretreatment of precursors. Moreover, based on Mössbauer spectroscopy, we infer that the reduction of structural ferric ions into ferrous ions in the lattice resulted in excellent magnetic separation of multiphase heterojunctions ZnO@ZnFe 2 O 4 during a single-mode MCP. Furthermore, the ζ potentials of ZnO@ZnFe 2 O 4 and ZnFe 2 O 4 indicate that cationic dyes could be spontaneously adsorbed onto the negatively charged surface of ZnO@ZnFe 2 O 4. Thus, the visible-light-driven catalytic mechanism of ZnO@ZnFe 2 O 4 was also proposed. Additionally, the aforementioned single-mode MCP strategy could also endow P25-based TiO 2 with excellent visible light-responsive photo-activities for effective degradation of estradiol. To our best knowledge, this is the first report associated with a novel single-mode MCP method to endow ZnO@ZnFe 2 O 4 or P25-based TiO 2 with an enhanced visible light-responsive (λ ≥ 420 nm) photoactivity. [ABSTRACT FROM AUTHOR]

To enhance the catalytic reactivity of millimeter-scale particles of sponge iron ( s -Fe 0 ), Cu 2+ ions were deposited on the surface of s -Fe 0 using a simple direct reduction reaction, and the catalytic properties of the bimetallic system was tested for removal of rhodamine B (RhB) from an aqueous solution. The influence of Cu 0 loading, catalyst dosage, particle size, initial RhB concentration, and initial pH were investigated, and the recyclability of the catalyst was also assessed. The results demonstrate that the 3 ∼ 5 millimeter s -Fe 0 particles ( s -Fe 0 (3 ∼ 5 mm)) with 5 wt% Cu loading gave the best results. The removal of RhB followed two-step, pseudo-first-order reaction kinetics. Cu 0 – s -Fe 0 showed excellent stability after five reuse cycles. Cu 0 – s -Fe 0 possesses great advantages compared to nanoscale zero-valent iron, iron power, and iron flakes as well as its bimetals. The surface Cu 0 apparently catalyzes the production of reactive hydrogen atoms for indirect reaction and generates Fe-Cu galvanic cells that enhance electron transfer for direct reaction. This bimetallic catalyst shows great potential for the pre-treatment of recalcitrant wastewaters. Additionally, some oxides containing iron element are selected to simulate the adsorption process. The results prove that the adsorption process of FeOOH, Fe 2 O 3 and Fe 3 O 4 played minor role for the removal of RhB. [ABSTRACT FROM AUTHOR]

To investigate the removal capability of millimetric zero valent iron (mmZVI), sponge iron (s-Fe 0 ) particles were characterized with XRD, XPS, TEM, HRSEM and EDS techniques. Moreover, the roles of particle size, catalyst dosage, dye concentration, mixing conditions (e.g. ultrasound (US), stirring or shaking), and regeneration treatment were studied with the removal of cationic triphenylmethane dyes. Notably, the reduction process was also revealed as compared to nanoscale zero valent iron (nZVI), microscale iron power, and iron scurf. Furthermore, the reductive mechanism was exemplified with brilliant green. The results demonstrated that (1) the synergetic effect between US and s-Fe 0 greatly enhanced the removal of dyes, (2) the dosage of preferred s-Fe 0 (1–3 mm) particles was optimized as 30.0 g/L; (3) reuse cycles of s-Fe 0 catalyst were enhanced with the assistance of diluted HCl solution; (4) the main degradation routes included the cleavage of conjugated structure reactions, N-de-ethylation reactions, hydroxylation reactions, the removal of benzene ring reactions, and opening ring reactions. Accordingly, the pretreatment of aqueous solution over s-Fe 0 was hypothesized to achieve mainly through direct reduction reaction by electron transfer and indirect reductive reactions by the highly activated hydrogen atom. Additionally, decoration with noble metals was utilized to reveal the reaction mechanism. [ABSTRACT FROM AUTHOR]

[Display omitted] • Thiourea (TU) is selected for a Microwave (MW)-induced pyrolysis of fly ash. • The parameters include fly ash to SiC of 1:9, 5–23.1 wt% TU, 380–610 °C and N 2. • TU reinforced the MW-absorbing properties of fly ash and shortened pyrolysis time. • The presence of TU could transform the targeted heavy metals into metal sulfides. • Unintentionally-Produced Persistent Organic Pollutants were also detoxified. Presently, it is a great challenging issue to inhibit the regeneration for dioxin and simultaneously detoxify Municipal solid waste incinerators (MSWI) fly ash with conventional Hagenmaier pyrolysis process (250–400 °C). The addition of inorganic S- and/or N-containing dioxin inhibitors could effectively inhibit the catalytic roles of residual heavy metals (HMs; e.g. Cu, Pb) for formation pathway of dioxin. In this study, we conducted a newly-proposed single-mode Microwave (MW)-based Hagenmaier process to investigate the impact of N, S-containing inhibitors of Thiourea (TU) on inhibiting the catalytic roles of targeted HMs and simultaneously detoxifying fly ash as well as to elucidate the corresponding mechanism. Synchrotron radiation analysis verified the sulfidation of targeted HMs including Cu and Pb, indicating the inhibition routes for dioxin regeneration. Moreover, the pyrolysis products of TU could apparently increase the MW-absorption properties of fly ash layer, and shorten by ~81.5% of processing time compared with that in the absence of TU. Under the optimized conditions (pyrolysis temperature of 480 °C, a mass ratio of fly ash to SiC as 1:9 and the addition of 23.1 wt% TU), ~99.2% of dioxin and ~94.1% of the bioassay-derived 2,3,7,8-tetrachlorodibenzo-p-dioxin toxic equivalent values (Bio-TEQs) were eliminated. Furthermore, the fundamental mechanism of a single-mode MW-induced Hagenmaier process was also proposed in detail. Additionally, a series of Unintentionally-Produced Persistent Organic Pollutants (UP-POPs) including chlorobenzenes were also detoxified by a single-mode MW-based Hagenmaier pyrolysis process, simultaneously. To the best of our knowledge, this is the first report adopting TU to inhibit the regeneration of dioxin and simultaneously detoxify fly ash by a single-mode MW-based pyrolysis process. [ABSTRACT FROM AUTHOR]

Abstract: In this research, we choose photolysis degradation (PD) course and H2O2-enhanced PD (HPD) course using UV–vis light from two microwave-powered electrodeless discharge lamps (MPEDL-2) as simplified models. The results verified that (1) ∼70% and 99.7% of MG were removed in PD and HPD courses within 5min irradiation, and PD course was proved to be dependent on ml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" display="inline" overflow="scroll"> O 2 - , (2) major routes were related to transformation of MG into malachite green carbinol base (MGCB), which could be further decomposed into 4-dimethylaminobenzophenone (DLBP), and (3) after 0.5min irradiation, PD course verified that ∼30% and 1% of MG was converted into MGCB and DLBP; for comparison, HPD course demonstrated that ∼12.9% and 28.5% of MG was transformed into MGCB and DLBP. Accordingly, we draw conclusions that degradation mechanism of MG could be revised as seven steps with MGCB as a key product and pH variation of aqueous dyes solution played minor role. Additionally, these conclusions were also enlightened for degradation of MG by advanced oxidation process. [Copyright &y& Elsevier]

Abstract: Aqueous crystal violet (CV) solutions containing P25–TiO2 photocatalyst were irradiated with ultraviolet–visible (UV–vis) light from two microwave-powered electrodeless discharge lamps (EDL-2). The results demonstrated that approximately 94.4% of CV was effectively removed after 3min of irradiation, with a pseudo-first order kinetic constant of 0.838min−1. According to 32 kinds of products, a five-step degradation pathway of CV was proposed. Further investigations showed that (1) three kinds of N-demethylated products and 4-dimethylaminobenzophenone (DLBP) were the main intermediates; (2) malachite green (MG) and leuco-crystal violet could not be generated by N-demethylation and phototransformation reactions, respectively; (3) bis(4-(dimethylamino)phenyl)methanone preferentially generated via decomposition of the conjugated structure of CV could be further N-demethylated into DLBP. Moreover, the unique degradation pathways of CV and MG were ascribed to the different substituents on the conjugated structures. Additionally, the cost and kinetic constant of different processes was also evaluated, and the results indicated the feasibility of this method for treatment of CV in field situations. [ABSTRACT FROM AUTHOR]

Abstract: This work was originally performed to compare H2O2-based degradation of aqueous malachite green (MG) under microwave (MW)-enhanced and conventional heating (CH)-enhanced conditions, with the whole reaction courses traced by UV–vis spectrophotometer. The results showed that the higher discoloration rates of MG were available during MW-enhanced process, implying that the special heating way of MW might be more benefit for the generation of hydroxyl radicals than that of CH. Furthermore, major intermediates were separated and identified by HPLC–ESI-MS and GC–MS techniques. On the basis of 53 intermediates, degradation mechanism was deduced as follows: firstly, N-de-methylation reactions. Secondly, adduction reactions. Thirdly, decomposition of conjugated structure reactions of MG. Fourthly, removal of benzene reactions. Finally, open-ring reactions. Additionally, results revealed that microwave-enhanced H2O2-based treatment had more advantages, such as higher degradation efficiency, and no removal of catalyst after treatment. [Copyright &y& Elsevier]

The possibility of application of chitosan-modified zeolite as sorbent for Cu(II), Zn(II), Mn(II), and Fe(III) ions and their mixtures in the presence of N-(1,2-dicarboxyethyl)-D,L-aspartic acid, IDHA) under different experimental conditions were investigated. Chitosan-modified zeolite belongs to the group of biodegradable complexing agents used in fertilizer production. NaP1CS as a carrier forms a barrier to the spontaneous release of the fertilizer into soil. The obtained materials were characterized by Fourier transform infrared spectroscopy (FTIR); surface area determination (ASAP); scanning electron microscopy (SEM-EDS); X-ray fluorescence (XRF); X-ray diffraction (XRD); and carbon, hydrogen, and nitrogen (CHN), as well as thermogravimetric (TGA) methods. The concentrations of Cu(II), Zn(II), Mn(II), and Fe(III) complexes with IDHA varied from 5–20 mg/dm3 for Cu(II), 10–40 mg/dm3 for Fe(III), 20–80 mg/dm3 for Mn(II), and 10–40 mg/dm3 for Zn(II), respectively; pH value (3–6), time (1–120 min), and temperature (293–333 K) on the sorption efficiency were tested. The Langmuir, Freundlich, Dubinin–Radushkevich, and Temkin adsorption models were applied to describe experimental data. The pH 5 proved to be appropriate for adsorption. The pseudo-second order and Langmuir models were consistent with the experimental data. The thermodynamic parameters indicate that adsorption is spontaneous and endothermic. The highest desorption percentage was achieved using the HCl solution, therefore, proving that method can be used to design slow-release fertilizers. [ABSTRACT FROM AUTHOR]

• A washing pretreatment containing phosphate anions was adopted to stabilize heavy metals. • The adsorbed fly ash was further detoxified by a single-mode microwave process. • The detoxification was optimized with wet fly ash to SiC of 2:10, 23.1% thiourea and ~480 °C. • The polychlorinated dibenzo-p-dioxins and dibenzofurans were destructed by ~99.1%. • MW-based pyrolysis of thiourea greatly prompted the generation of hot spots in fly ash. Presently, control of the environmental risk posed by fly ash from municipal solid waste incinerators (MSWIs) urgently requires novel strategies to stabilize targeted heavy metals (HMs), detoxify toxic organic pollutants and separate residue alkali metal chlorides. In this study, a washing pretreatment containing phosphate (P) anions was adopted to stabilize HMs, and the main influencing factors as well as the thermodynamics were investigated. The results show that the adsorption process fits well with the Langmuir model, giving a maximal adsorption capacity of 114.35 mg P g−1 with a preferred liquid-to-solid ratio of 2.5 L g−1; the thermodynamics equation indicated that this was a spontaneous, endothermic and entropy-increasing process. Moreover, wet fly ash absorbed with P anions was further irradiated with single-mode microwave (MW) energy. The results show that under the preferred conditions of a mass ratio of SiC to wet fly of 10:2, temperature of ~480 °C and N 2 atmosphere, ~99.1% of the total PCDD/Fs were efficiently degraded, accompanied by a residual toxicity equivalent of 13.0 ng I-TEQ/kg. Notably, the presence of thiourea (TU) shortened the MW irradiation time by 27.8%–61.5% compared with the absence of TU and enhanced the generation of hot spots. Furthermore, the principal parameters of MW-based Hagenmaler reactions apparently demonstrate significant difference with traditional heating-based Hagenmaler reactions mainly including the pyrolysis temperature over the range of 200–450 °C, an inert atmosphere and at least 1 h of residue time. Accordingly, this study provides a promising alternative strategy to stabilize HMs and detoxify organic pollutants, accompanied with a separation of residue alkali metal chlorides. [ABSTRACT FROM AUTHOR]

The rapid urbanization and industrialization in China have led to an urgent dilemma for controlling urban air pollution, including the intensified emission of gasoline vapor into the atmosphere. Herein, we selected highland barley straw as a raw material and KOH and tetramethylammonium hydroxide (TMAOH) as activators to synthesize nitrogen-doped layered porous carbon (K-thAC) by a three-step activation method. The obtained K-thAC materials had a high specific surface area, reaching 3119 m2/g. Dynamic adsorption experiments demonstrated a superior adsorption capacity of up to 501 mg/g (K-thAC-25) for gasoline vapor compared with other documented carbon adsorbents. Moreover, adjusting the ratio of raw materials with a series of active ingredients could further improve the pore properties of the obtained K-thACs and their adsorption performance for gasoline vapor. Furthermore, the K-thAC materials were also characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), synchronous thermogravimetry (STA), X-ray powder diffraction (XRD), energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and nitrogen adsorption tests. This study synthesized a novel plant-based material to treat gasoline vapor pollution efficiently. [ABSTRACT FROM AUTHOR]

The recycling of REEs from the end of life (EoL) products, such as nickel metal hydride batteries (NiMH), offers great opportunities for their supply in Europe. In the presented paper, the application of 'green' extractants such as citric (CA), metatartaric (TA), and ethylenediaminedisuccinic acid (EDDS) (also with H2O2 addition) for the recovery of REEs was studied. The studies were conducted considering the effects of the phase contact time, the initial concentration of CA, TA, and EDDS, as well as H2O2, pH, and temperature. It was found that the addition of TA to the CA solution meant that higher rates of metal ion binding and, thus, leaching was observed. The optimal conditions were obtained in the system: CA-TA and H2O2 for the concentration 0.6M-0.3 M-2%. [ABSTRACT FROM AUTHOR]

Three acrylic-based superabsorbents—TerraHydrogel®Aqua (THA), Zeba®Hydrogel (ZH) and Agro®Hydrogel (AH) were used to investigate the influence of chemical conditions on kinetic and adsorption behavior towards metal ions in the presence of a chelating agent of a new generation called ethylenediamine-N,N′-disuccinic acid (EDDS). The effects of relevant parameters—mainly including those of sorbent dose, pH of the solution and initial concentration of Cu(II), Zn(II), Mn(II) and Fe(III) complexes with EDDS as well as phase contact time and temperature—on the adsorption efficiency were studied in detail by the static method. The experimental data were also characterized by kinetic and adsorption parameters obtained based on the Langmuir and Freundlich models of sorption as well as the Lagergren, Ho and McKay and Weber–Morris models. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Municipal incinerator fly ash was detoxified by a single-mode microwave process. • The detoxification was optimized with fly ash to SiC of 1:9, 23.1% urea and ˜ 480 °C. • The polychlorinated dibenzo-p-dioxins and dibenzofurans was destructed with ˜ 98.5%. • MW-based pyrolysis of urea (133˜300 °C) was favourable for generation of hot spots. Abstract The detoxification of municipal solid waste incinerator (MSWI) fly ash dioxins urgently requires an effective treatment technology. In this study, we adopted a single-mode microwave (MW)-based pyrolysis to treat MSWI fly ash under N 2 atmosphere and further elucidated the main influencing factors, including the chemical inhibitor, for dioxin control. The results show that (1) the detoxification process was optimized with a mass ratio of fly ash to SiC of 1:9, 23.1% (wt%) urea addition and pyrolysis temperature of ˜ 480 °C; (2) the total polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) destruction efficiency and the bioassay-derived 2,3,7,8-TCDD toxic equivalent (Bio-TEQ) removal efficiency reached 98.5% and 97.9%, respectively, accompanied with ˜ 1.3% of the total amount of dioxin being submitted to exhaust gas; (3) the MW-based pyrolysis of urea (133˜300 °C) was favourable for the generation of hot spots as well as the PCDD/F rapid destruction in fly ash. In addition, the leaching toxicity of heavy metals was also partially reduced after MW pyrolysis reactions. To the best of our knowledge, this is the first report adopting a MW-based pyrolysis to eliminate dioxin in MSWI fly ash with the addition of urea, which is a promising alternative to current methods. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Millimetric sponge iron (s-Fe0) were decorated with palladium for removal of TBBPA. • Series of solvents, including CH 3 OH:H 2 O, CH 3 OH, CH 2 Cl 2 and isopropanol, were adopted. • Products were identified by liquid chromatography time-of-flight mass spectrometry. • Not electron transfer but H-atom transfer was affected by the presence of cosolvents. Abstract The exploration of an effective treatment is necessary to eliminate the emerging environmental pollutant tetrabromobisphenol A (TBBPA). In this study, a direct reduction reaction was adopted to synthesize millimetre-scale palladised sponge iron (Pd0-s-Fe0), the main influencing factors were further explored, the degradation intermediates were identified in detail, and the cosolvent effect on the degradation mechanism was determined. The results show that (1) within a 30 min reaction, Pd(II) ions in aqueous solution were successfully decorated onto the s-Fe0 surface as supported by XPS, SEM, EDS, and ICP-OES analyses, (2) after 120 min of reaction, the normalized removal of TBBPA was ∼92.2% over 0.06 wt%-Pd0-s-Fe0, compared with 98.2% over 0.06 wt%-Pd-nZVI and 44.4% over bare nZVI. Moreover, the extend of debromination of TBBPA surprisingly increased as the ratio of the CH 3 OH:H 2 O cosolvent decreased, compared with the debromination rates that were greatly restricted in CH 3 OH (100%, v/v), CH 2 Cl 2 (100%, v/v) and isopropanol (100%, v/v), respectively. Furthermore, the O -methylation reactions over Pd0-s-Fe0 produced unique intermediates, including 2,6-dibromo-4-(2-(3,5-dibromo-4-methoxyphenyl)propan-2-yl)phenol (MeO-TBBPA) and 5,5′-(propane-2,2-diyl)bis(1,3-dibromo-2-methoxy-benzene) (diMeO-TBBPA) with lower toxicity. This study greatly enriches knowledge regarding the degradation mechanism of TBBPA over millimetre-scale sponge iron. [ABSTRACT FROM AUTHOR]

Chitosan hydrogel beads (CHBs) have displayed prominent advantages as adsorbents, including easy separation after adsorption. To further increase their adsorption capacity, CHBs were modified with malic acid and further freeze-dried. The structural characteristics of malic acid modified CHBs (mCHBs) were explored along with the factors primarily influencing their effectiveness. The mechanisms of Cr(VI) and Cu(II) ion removal were reevaluated in detail. The results show that (1) porous mCHBs were clearly observed by scanning electron microscopy, accompanying with the observation of particles of elemental Cu or Cr about 300 nm in diameter within the pores of the mCHBs; (2) the maximum equilibrium adsorption capacity of mCHBs for Cr(VI) was 383.2 mg g −1 , reached within 2 h, and the removal of Cr(VI) was an efficient adsorption-reduction process. For comparison, the chemisorption of Cu(II) onto mCHBs formed a monolayer with a maximum equilibrium adsorption capacity of 183.8 mg g −1 , reached within 24 h, and the adsorption of Cu(II) ions was spontaneous and endothermic. Moreover, CHBs modified with a series of carboxylic acids also showed enhanced removal of heavy metals. In addition, the presence of Cu(II) ions in the matrix of mCHBs could function as an effective adsorbent for removal of phosphate ions. [ABSTRACT FROM AUTHOR]

Currently, the pharmaceutical and personal care products (PPCPs) have posed great challenge to advanced oxidation techniques (AOTs). In this study, we decorated sponge iron (s-Fe0) with Cu and Pd (s-Fe0-Cu-Pd) and further optimized the synthesis parameters with a response surface method (RSM) to rapidly degrade diclofenac sodium (DCF). Under the RSM-optimized conditions of Fe: Cu: Pd = 100: 4.23: 0.10, initial solution pH of 5.13, and input dosage of 38.8 g/L, 99% removal of DCF could be obtained after 60 min of reaction. Moreover, the morphological structure of trimetal was characterized with high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), X-ray diffraction (XRD), X-ray photoelectron spectra (XPS). Electron spin resonance (ESR) signals have also been applied to capture reactive hydrogen atoms (H*), superoxygen anions, hydroxyl radicals, and single state oxygen (1O 2). Furthermore, the variations of DCF and its selective degradation products over a series of s-Fe0-based bi(tri)metals have been compared. Additionally, the degradation mechanism of DCF has also been explored. To our best knowledge, this is the first report revealing the selective dechlorination of DCF with low toxicity over Pd–Cu co-doped s-Fe0 trimetal. • SynThesis of Pd–Cu-doped sponge iron (Fe–Cu–Pd) was optimized with a response surface method. • The donated electrons prompt the reactive oxygen species (ROSs) and activated hydrogen atoms ([H]*). • Electron spin resonance spectra verify generation of [H]*, OH, O 2 − and 1O 2 over Fe–Cu–Pd. • The role of [H]* over Fe–Cu–Pd prefers the dichlorination route of diclofenac with low toxicity. • Fe–Cu–Pd trimetal could achieve the selective degradation of DCF with low toxicity. [ABSTRACT FROM AUTHOR]

Tetrabromobisphenol A (TBBPA) was a potential persistent organic pollutants. This study synthesized s-Fe/Cu bimetallic particles by decorated sponge iron (s-Fe) with Copper (Cu) to degrade TBBPA. S-Fe/Cu bimetallic particles was further characterized by XRD, XPS, SEM and EDS. The optimal TBBPA removal efficiency was 95.9%. Among the theoretical Cu mass loading increasing from 0 wt% to 6 wt%, 4 wt% mass loading was the best; with TBBPA initial concentration increased from 5 mg/L to 30 mg/L, TBBPA removal efficiency decreased from 91.2% to 73.0%; also, when dosage increased from 10 g/L to 30 g/L, removal efficiency increased from 58.1% to 95.9%; pH 6.5 were beneficial to degrading TBBPA and the s-Fe/Cu bimetallic particles showed strong catalytic ability after 4 reuse cycle. Kinetic analysis showed that the degradation of TBBPA obeyed pseudo-first-order kinetics. In addition, Liquid Chromatography Time-of-Flight Mass Spectrometry (LC/TOF/MS) detected degradation products including debromination products, hydroxylation products, single aromatic ring products and O -methylating product, which demonstrated that the main degradation pathway were debromination, hydroxyl, β -scission and O -methylation reactions. [ABSTRACT FROM AUTHOR]

To date, zero-valent iron (ZVI)-based technique has encountered a baffle, challenging simultaneous detoxification of refractory rhodamine B (RhB) and p -nitrophenol (PNP) possessing strong electronwithdrawing nitro-group. In this study, we synthesized Ag-Cu decorated sponge iron (s-Fe0)-based trimetal for simultaneous degradation of RhB and PNP. The results show that Cu-Ag co-doping s-Fe0 (s-Fe0-(Cu-Ag)) achieves approx. 90.6 % of maximized removal of RhB; the preferred s-Fe0-(5 wt %Cu-1 wt %Ag) assisted with 6 L/min aeration rate simultaneously declines RhB and PNP within 10 recycling tests; non-aeration process obtains a complete reduction of PNP as well as merely approx. 23.9 % removal of RhB. Moreover, the Cu-Ag microstructure covering s-Fe0-(Cu-Ag) has been characterized in detail. Furthermore, the electron spin resonance (ESR) spectra have been applied to investigate simultaneous generation of reactive oxygen species (ROS s) and hydrogen radicals ([H] abs) over s-Fe0-(Cu-Ag). To our best knowledge, this is the first study reporting the enhanced bifunctional catalysis of s-Fe0-(Cu-Ag)/O 2 for simultaneous degradation of RhB and PNP. [Display omitted] • Ag-Cu-doped sponge iron (s-Fe0-(Cu-Ag)) could simultaneously detoxify RhB and PNP. • s-Fe0-(Cu-Ag) prompts reactive oxygen species (ROSs) and activated hydrogen atoms ([H]*). • Electron spin resonance (ESR) spectra verify the generation of [H]* , •OH, •O 2 - and 1O 2. • ROSs and [H]* achieve rapid oxidation of RhB and reduction of PNP, respectively. [ABSTRACT FROM AUTHOR]

Abstract: Nickel oxide catalyst was obtained by precipitation–oxidation method with the assistance of microwave irradiation. The samples were characterized by X-ray diffraction, Raman spectrophotometer, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, surface area and porosity analyzer. On the basis of the results, the as-prepared product was nano-NiO2 with OH group and active oxygen. The catalytic activity of the as-prepared product might be attributed to its microwave absorbing property and the role of active oxygen, OH group under microwave irradiation. The microwave induced catalytic degradation process (MICD) with as-prepared product was further applied to degrade triphenylmethane dye crystal violet (CV). 97% of a 100mgL−1 sample of CV was rapidly degraded in 5min with the corresponding 81% TOC removal. The main intermediates were separated and identified by LC–ESI-MS and GC–MS techniques. The LC–ESI-MS analytical results demonstrated that a series of N-de-methylation products were obtained in a stepwise manner, namely mono-, di-, tri-, tetra-, penta-, and hexa-de-methylated CV species. Nine organic acids with benzene ring and four low molecular acids were yielded with the assistance of GC–MS. The proposed degradation pathways were discussed in this study. The degradation processes might include N-de-methylation, destruction of conjugated structure and opening-benzene ring. MICD, as a potential technique with wide application perspective, can be used to purify triphenylmethane dye wastewater with nanosized nickel dioxide. [Copyright &y& Elsevier]