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One important pathway for human exposure to per- and polyfluorinated alkyl substances (PFASs) is based on the Earth's atmosphere. Figuring out atmospheric transformation mechanism of PFASs is beneficial for understanding their effects on humans. However, the focus on the molecular-level transformation mechanism of emerging PFASs in the atmosphere still need to be improved. In this work, we used quantum chemistry calculation to study ·OH-initiated degradation mechanism of a new fluorinated alcohol (C 3 F 7 OCHFCF 2 SCH 2 CH 2 OH, abbreviated FESOH) in the presence of oxygen and nitric oxide. Three main conformers of FESOH share the similar initial mechanism that the abstraction reactions of H atom at α-C and β-C atoms are the main pathways (activation free energies of <10 kcal mol−1 at 298 K), but make different contributions to the whole FESOH degradation. Subsequent transformations starting from initial products at α-C atoms will reunite with that at β-C atoms, and the intermediate (C 3 F 7 OCHFCF 2 S·) is produced. After O 2 addition to the intermediate and the following SO 2 elimination, the alkyl radical (C 3 F 7 OCHFCF 2 ·) can undergo consecutive chain cleavage cycles to form CF 3 OH finally. The bioaccumulation evaluation shows that FESOH and its transformation products cannot be accumulated in organisms. The work is helpful for knowing the atmospheric fate of FESOH at molecular level and can provide some insight into the transformation of other PFASs in the atmosphere. [Display omitted] • Three main conformers of FESOH account for approximate 99% of all conformers. • The H-abstraction at α-C and β-C mainly occurs for ·OH-initiated FESOH degradation. • Subsequent reactions can form alkyl peroxynitrite, fluorinated aldehyde and CF 3 OH. • FESOH and its transformation products cannot be accumulated in organisms. [ABSTRACT FROM AUTHOR]

Abstract Methanesulfinic acid (MSIA), an organic sulfur compound, is mainly produced in the oxidation process of dimethyl sulfide in the atmosphere. The properties of MSIA at the air-water interface were studied using molecular dynamics (MD) simulations. The result shows that the lowest system free energy is located at the interface. Because the free energy difference between the interface and water phase is 3.2 kJ mol−1, the MSIA molecule can easily get out of the free energy well and travel to water phase by the thermal motion, leading to only a 21% probability of its occurrence at the interface. The MSIA molecule tends to tilt at the interface with the sulfino group (-S(O)-OH) pointing toward the water phase. The feature of hydration status at the air-water interface may be favorable to the heterogeneous oxidation of MSIA. Graphical abstract Unlabelled Image Highlights • The properties of MSIA at the air-water interface are studied using MD simulations. • The lowest free energy is located at the air-water interface. • Probability of MSIA at the interface is about 21%. • The tilted orientation at the interface is predominant. • The feature of hydration status at the interface is found. [ABSTRACT FROM AUTHOR]

By theoretical calculations, the gas-phase SO 2 hydration reaction assisted by methylamine (MA) and dimethylamine (DMA) was investigated, and the potential contribution of the hydrated product to new particle formation (NPF) also was evaluated. The results show that the energy barrier for aliphatic amines (MA and DMA) assisted SO 2 hydration reaction is lower than the corresponding that of water and ammonia assisted SO 2 hydration. In these hydration reactions, nearly barrierless reaction (only a barrier of 0.1 kcal mol −1 ) can be found in the case of SO 2 + 2H 2 O + DMA. These lead us to conclude that the SO 2 hydration reaction assisted by MA and DMA is energetically facile. The temporal evolution for hydrated products (CH 3 NH 3 + -HSO 3 - -H 2 O or (CH 3 ) 2 NH 2 + -HSO 3 - -H 2 O) in molecular dynamics simulations indicates that these complexes can self-aggregate into bigger clusters and can absorb water and amine molecules, which means that these hydrated products formed by the hydration reaction may serve as a condensation nucleus to initiate the NPF. [ABSTRACT FROM AUTHOR]

Limononic acid (3-isopropenyl-6-oxoheptanoic acid, LA), as an important precursor of secondary organic aerosols (SOA), has attracted extensive attention in the field of atmospheric chemistry. However, its microscopic oxidation mechanism is still unclear. In this study, the density functional theory calculations were conducted to study the oxidation mechanism of LA by ·OH in aqueous phase. The results show that the reactions of hydroxylation are more likely to occur than the dehydrogenation reaction, because of the lower free energy barrier (2.3–5.4 kcal mol−1). At 298 K, the total rate constant of the reaction initiated by ·OH is 1.06 × 1010 M−1 s−1, which fits the experimental value well. Among all reactions, the hydroxylation reaction in C 9 site of LA is the most favorable pathway, and the corresponding hydroxylation intermediate (IM4) can react with ·OH, H 2 O, dissolved O 2 , and HO 2 ·. Three important tropospheric free radicals (R·, RO· and RO 2 ·) are generated during the subsequent reaction process. Meanwhile alcohols, ketones, aldehydes, and oxidized acids can be formed in the overall reaction scheme. These products are the precursor for the formation of SOA, and this transformation process will increase the O/C ratio of aqueous phase SOA. This study has an important significance for understanding the oxidation mechanism of monoterpenoids in the atmospheric aqueous phase. [Display omitted] • OH-addition reaction of C 9 site is more like to occur of LA. • The intermediate can react with ·OH, H 2 O, dissolved O 2 , and HO 2. • Three important tropospheric free radicals (R·, RO· and RO 2 ·) are generated during the reaction process. • The transformation process will increase the O/C ratio of aqueous phase SOA. [ABSTRACT FROM AUTHOR]

As the major stabilizer for crude oil emulsion in petroleum industry, asphaltene has been concerned more widespread with the increasing demand of energy in the world. The in-depth understanding on its properties at crude oil-water interface has some beneficial effect on dealing with the emulsion in oil industry. To investigate these interfacial properties at molecular level, molecular dynamics (MD) simulation was utilized. The results show that asphaltene molecules tend to different orientation between them at this interface so as to decrease the repulsive force of aggregation process. Moreover, the contributors to asphaltene stability at crude oil-water interface also were discussed. It mainly includes hydrogen bond networks around asphaltene polar group. The hydrogen bond networks behave like an anchor to grab hold of asphaltene at the interface. The aggregation properties of asphaltene at oil-water interface were obtained by using the umbrella sampling method. The results indicate that aggregation state is most stable for asphaltene molecules at oil-water interface and the system free energy will increase after the aggregate be broken. [ABSTRACT FROM AUTHOR]

In this paper, the degradation mechanism and eco-toxicity assessment of bisphenol S (BPS) was studied in the aqueous environment based on the heterogeneous activation of peroxymonosulfate (PMS) through spinel tricobalt tetraoxide (Co 3 O 4) catalyst using density functional theory (DFT) and computational toxicology methods. The result indicates that (100) and (311) surfaces have the higher proportion of bivalent cobalt, the increase of charge transfer, negative adsorption energy, and the lower surface energy. They can more effectively promote the decomposition of PMS to generate reactive oxide species. When generated oxidants react with BPS, HO•-addition reaction at the ortho -C atom-sites plays a dominant role in the system Co 3 O 4 /PMS. The presence of SO 4 •-, HO•, and O 2 promotes the formation of transformation intermediates and products. The formation pathways of important experimental intermediates hydroquinone, p -hydroxybenzenesulfonic acid, and 3, 4-dihydroxybenzenesulfonic acid are identified. And, some hydroxylation products that are not identified in the experiment are determined. The eco-toxicity evaluation shows that most of the decomposition products are completely harmless or significantly reduced compared to BPS. This study not only provides insights into the degradation mechanism of BPS in Co 3 O 4 /PMS system, but also is expected to be a guide for further experimental research and the design and optimization of the activated catalysts in sulfate radical-based advanced oxidation technologies. [Display omitted] • Co 3 O 4 (100) and (311) surfaces are more effectively promote the PMS decomposition. • The most reactive-site of BPS is the ortho -C atom. • OH.•-initiated plays a dominant role in the degradation process of BPS, not SO 4 •-. • Hydroquinone and p-hydroxybenzenesulfonic acid are important intermediates. • Compared with BPS, most decomposition products are harmless or reduced. [ABSTRACT FROM AUTHOR]

Bioaccumulation of perfluoroalkyl and polyfluoroalkyl substances (PFASs) is an important indicator of their hazard. Partitioning to membrane phospholipids is one of the pathways for their bioaccumulation. However, the molecular mechanism on PFASs uptake into membrane phospholipids is not yet to be fully understood. In this work, we used molecular dynamics (MD) simulations to study the uptake processes of PFOS and its alternatives (6:2 Cl-PFESA and OBS) into DPPC bilayers, and to evaluate their interaction with DPPC bilayers and their effect on properties of DPPC bilayers. The result of free energy changes shows that a barrier of 2–3 kcal mol−1 exists when these adsorbed PFASs on the surface are absorbed into DPPC bilayers. After incorporating into DPPC bilayers, three DPPC molecules interact with and thus stabilize a PFOS (or 6:2 Cl-PFESA or OBS) molecule. And another role of the three DPPC molecules is to shield these PFASs from exposure to water environment. These PFASs have the similar condensing effect on the model membrane. The molecular-level study is beneficial for understanding the bioaccumulation and toxicity of PFOS and its alternatives. [Display omitted] • The uptake of PFOS, 6:2 Cl-PFESA and OBS into DPPC bilayers is easy to happen. • A barrier of 2–3 kcal mol−1 needs to be overcome during the uptake processes. • Three DPPC molecules interact with a PFOS (or 6:2 Cl-PFESA or OBS) molecule. • A role of three DPPC molecules is to shield PFASs from exposure to water molecules. • PFOS, 6:2 Cl-PFESA and OBS have the similar condensing effect on DPPC bilayers. [ABSTRACT FROM AUTHOR]

Fenpiclonil is an agricultural phenylpyrrole fungicide, which raise the concern about its ecotoxicological effects. In this paper, we investigate the indirect photochemical transformation mechanisms, environmental persistence and eco-toxicity of fenpiclonil initiated by various active oxidants (1O 2 , •OH and SO 4 •‾) in aquatic environments. The results shown that 1O 2 can react with pyrrole ring by cycloaddition pathways to form the endo-peroxides. In addition, •OH and SO 4 •‾ initial mechanisms are calculated, suggesting that •OH-initiated mechanisms play a dominant role in the degradation process of fenpiclonil at high rate constants (2.26 × 109 M−1 s−1, at 298 K). The kinetic calculation results indicate that high temperature is more favorable for the degradation of fenpiclonil. To better understand the adverse effects of the transformation products formed during the subsequent reaction of •OH-adduct IM10, the computational toxicology has been used for the toxicity estimation. The results show that aquatic toxicity of these products decrease with degradation process, especially the decomposition products (TP3 and TP4). However, TP1 and TP2 are still toxic and developmental toxicant. The study provides guidance for further experimental research and industrial application of fungicide degradation from the perspective of theoretical calculation. ga1 • •OH-initiated mechanisms play a dominant role in the degradation process of fenpiclonil at high rate constants. • The rate constants and half-life of initial reactions of fenpiclonil with •OH, SO 4 •‾ and 1O 2 are calculated. • High temperature is more favorable for the initial degradation of fenpiclonil. • Transformation products with decreased aquatic eco-toxicity are still toxic and developmental toxicant. [ABSTRACT FROM AUTHOR]

• P-NP is completely degraded by tertiary ozonation. • The k total of degradation of p-NP initiated by O 3 alone is slow. • OH· can greatly promote the tranformation of p-NP in O 3 /UV process. • Some metabolites still have carcinogenic and teratogenic effects on organisms. P -nitrophenol (p-NP) is a recalcitrant organic compound attracted great environmental attention, but its degradation mechanism is indeterminacy, which challenges its treatment, migration, transformation and ecological impact in the environment. In the present study, the aqueous-phase decomposition process of p-NP initiated by O 3 has been investigated by a theoretical calculation method. The detailed possible reaction pathways for the oxidative degradation of p-NP by ozone have been proposed. The chemical reaction thermodynamics results show that the reaction barriers of all ozone-initiated pathways are below 15 kcal·mol−1, indicating that ozone can completely initiate the oxidation of p-NP under natural conditions. However, the kinetic results show that the initiation reaction of p-NP by ozone alone is relatively slow compared to the reaction by OH. Interestingly, under ultraviolet (UV) radiation, the dissolved ozone interacts with water and produces two active radicals: OH and HO 2 . The reaction rate of p-NP initiated with OH is much higher than that with ozone, implying that the OH produced in the photochemical process can improve the removal efficiency of p-NP. The intermediates generated in the ozone-initiated reaction have been found to decompose into small molecule organic acids, aldehydes and ketones. The potential carcinogenicities and teratogenicities of the transformation products have also been studied, and some of them still have carcinogenic activity, which deserve further attention. In addition, to our knowledge, this may be the first computational chemistry study on the degradation of p-NP initiated by HO 2 . All the results provide a new fundamental understanding for the migration and transformation of p-NP in water environment, and indicate that further assessment is needed for the impact of p-NP and especially its transformation products on the ecological environment in a significant way. [ABSTRACT FROM AUTHOR]

The bacteriostatic antibiotics, sulfamethoxazole (SMX) and trimethoprim (TMP), have frequently been found in wastewater and surface water, which raises the concerns about their ecotoxicological effects. The indirect photochemical transformation has been proven to be an efficient way to degrade SMX and TMP. In this study, the reaction mechanisms of the degradation by SMX and TMF by OH radicals were investigated by theoretical calculations. Corresponding rate constants were determined and the eco-toxicity of SMX and TMP and its degradations products were predicted using theoretical models. The results indicate that the most favorable pathways for the transformation of SMX and TMP are both •OH-addition reaction of benzene ring site with lowest Gibbs free energy barriers (6.86 and 6.21 kcal mol−1). It was found that the overall reaction rate constants of •OH-initial reaction of SMX and TMP are 1.28 × 108 M−1 s−1 and 6.21 × 108 M−1 s−1 at 298 K, respectively. When comparing the eco-toxicity of transformation products with parent SMX and TMP, it can be concluded that the acute and chronic toxicities of the degraded products are reduced, but some products remain harmful for organisms, especially for daphnid (toxic or very toxic level). This study can give greater insight into the degradation of SMX and TMP by •OH through theoretical calculations in aquatic environment. [ABSTRACT FROM AUTHOR]

[Display omitted] Energy consumption from air cooling systems in summer, water scarcity in hot regions, and the functional reusability of waste paper are emerging environmental problems. Finding solutions to these problems simultaneously remains a significant challenge. Herein, a superhydrophobic passive cooling Cellulose-CaCO 3 film with hierarchical nano-sheets was fabricated to realize daytime radiative cooling with a temperature drop of 15–20 °C in summer and water harvesting with harvesting efficiency of 387 mg cm−2h−1 bd utilization of recycled waste paper. The superhydrophobic Cellulose-CaCO 3 film demonstrates its self-cleaning properties against inorganic and organic pollutants. Furthermore, the superhydrophobicity of the film was maintained after base/acid corrosions, dynamic water flushing, and thermal treatment at 100 °C for 7 h, exhibiting good durability of the superhydrophobicity. Moreover, the superhydrophobic Cellulose-CaCO 3 film is nonflammable after exposure to fire combustion for 1 min. In addition to waste paper, waste maize straws, and pasteboards were also collected to produce superhydrophobic passive cooling films. Results indicate that the above three cellulose-based raw materials can be well used to prepare durable superhydrophobic passive cooling materials. Environmental toxicology assessments confirm the safety of the material. This study not only provides a protocol for preparing superhydrophobic materials; but also demonstrates their potential for passive cooling and water harvesting. [ABSTRACT FROM AUTHOR]

H 2 SO 4 is an important pollutant in the atmosphere, and it mainly be formed through the oxidation of SO 2. SO 3 produced from the oxidation of SO 2 is a precursor of H 2 SO 4. Considering that understanding of SO 3 hydration reaction at the air-water interface is limited, we combined the classical molecular dynamics simulations (classical MD) with Born–Oppenheimer MD simulations and ab initio calculations to study the SO 3 reaction with H 2 O at air-water interface. The free energy and impinging results indicate that the SO 3 molecules can easily be trapped by water droplets. After uptake by the interface, the SO 3 can react rapidly with water molecules to form the ion pair of HSO 4 − and H 3 O+ or H 2 SO 4 within a few picoseconds. In the interfacial hydration mechanism, the loop-structure formation is not prerequisite of the hydration reaction, which is obviously different from the corresponding gas-phase hydration reaction of SO 3. The work is meaningful for understanding the heterogeneous formation of H 2 SO 4 and the contribution of interfacial reaction to the new particle formation. • SO 3 can easily be trapped by water droplets. • The SO 3 hydration mechanism at the air-water interface was considered. • The loop-structure formation is not prerequisite of interfacial hydration of SO 3. [ABSTRACT FROM AUTHOR]

3,4-dihydroxy-2-butanone (DHBO) is a major oxidation product of IEPOX and can easily be oxidized in tropospheric aqueous phase. The aqueous oxidation mechanism of DHBO has investigated by DFT and initial reaction rate constants also have calculated through TST. In the aqueous phase, the following trend in reactivity of initial reaction can be obtained: OH ≫ SO 4 − > NO 3 , which bases on the calculated rate constants (k (OH) = 1.20 × 108 L mol−1 s−1, k (SO 4 −) = 8.51 × 105 L mol−1 s−1 and k(NO 3) = 2.86 × 105 L mol−1 s−1) at 298 K and 1 atm. After initial reaction, the major products of DHBO further react with OH radical at presence of O 2. The final products include acetic acid and methylglyoxal, which are important SOA precursors. This work provides a reference for oxidation mechanism of dihydroxycarbonyl of isoprene-driven in aqueous and help understand SOA formation. Image 1 • The aqueous oxidation mechanism of DHBO has been studied. • The OH.•-initiated reaction rate constant is 1.20 × 108 L mol−1 s−1 at 298 K and 1 atm. • Acetic acid and methylglyoxal of main products contribute to aqSOA formation. • The HO 2 and RO 2 of minor products increase the ozone yield. [ABSTRACT FROM AUTHOR]

Methanesulfinic acid (MSIA) is an important intermediate in the oxidation of dimethyl sulfide (DMS) in the marine boundary layer. The oxidation of MSIA by ozone in the gas phase to form methanesulfonic acid (MSA) was investigated using theoretical calculations in this paper. Three pathways can be found for the reaction of MSIA with ozone. The highest energy barrier is 13.02 kcal mol−1 in the most favorable pathway. By comparing the reaction rate of MSIA + O3 with that of MSIA + OH, it can be concluded that the oxidation of MSIA by O3 to form MSA is of minor significance relative to its oxidation by OH radical in the gas phase. This study can provide some information for the theoretical and experimental studies in the significantly heterogeneous and aqueous-phase oxidation of MSIA by O3. [ABSTRACT FROM AUTHOR]

In order to mitigate the harmful effects of eutrophication in water bodies, the applications of lanthanum-modified materials for phosphate removal from wastewater have attracted much attention. Unlike conventional adsorbents, plant wastes usually have poor adsorption abilities and are difficult to be reused for desorption of phosphate due to their small pore sizes and ununiform loading of modified ions. In this paper, a composite adsorbent (LC-MM) was synthesized by hydrothermal treatment of waste traditional Chinese medical materials (MMs) with load of lanthanum carbonate and co-heating treatment with coal fly ash (CFA), which was applied to remove phosphate from water. The results showed that maximum adsorption capacity of LC-MM was 52 mg g−1, and the LC-MM showed appreciable adsorption capacity of phosphate for agricultural wastewater in the presence of complex interfering ions and for urban surface waters with low phosphate concentrations. Five adsorption-desorption cycles showed good reusability. The mechanism study showed that the La3+ ions were more uniformly distributed on the surface of the absorbents with the introduction of Fe3+, Al3+, Mg2+ and Ca2+ ions in CFA. The ligand exchange between phosphate and carbonate, the internal spherical complexation formed by lanthanum ion and phosphate, and surface chemical precipitation attachment are the main reasons why the adsorption capacity of LC-MM approached or even surpassed that of conventional lanthanum-modified adsorbents. In conclusions, this work proposed an effective method for the modification of plant materials. [Display omitted] • Reuse of two types of waste after treatment. • A method to improve the inefficiency of phosphate adsorption by plant materials. • The mechanism of modification is to influence the state of lanthanum on the surface of the carrier. • Effect of phosphate separated after adsorption on plant growth. [ABSTRACT FROM AUTHOR]

In order to mitigate the harmful effects of eutrophication in water bodies, the applications of lanthanum-modified materials for phosphate removal from wastewater have attracted much attention. Unlike conventional adsorbents, plant wastes usually have poor adsorption abilities and are difficult to be reused for desorption of phosphate due to their small pore sizes and ununiform loading of modified ions. In this paper, a composite adsorbent (LC-MM) was synthesized by hydrothermal treatment of waste traditional Chinese medical materials (MMs) with load of lanthanum carbonate and co-heating treatment with coal fly ash (CFA), which was applied to remove phosphate from water. The results showed that maximum adsorption capacity of LC-MM was 52 mg g−1, and the LC-MM showed appreciable adsorption capacity of phosphate for agricultural wastewater in the presence of complex interfering ions and for urban surface waters with low phosphate concentrations. Five adsorption-desorption cycles showed good reusability. The mechanism study showed that the La3+ ions were more uniformly distributed on the surface of the absorbents with the introduction of Fe3+, Al3+, Mg2+ and Ca2+ ions in CFA. The ligand exchange between phosphate and carbonate, the internal spherical complexation formed by lanthanum ion and phosphate, and surface chemical precipitation attachment are the main reasons why the adsorption capacity of LC-MM approached or even surpassed that of conventional lanthanum-modified adsorbents. In conclusions, this work proposed an effective method for the modification of plant materials. [Display omitted] • Reuse of two types of waste after treatment. • A method to improve the inefficiency of phosphate adsorption by plant materials. • The mechanism of modification is to influence the state of lanthanum on the surface of the carrier. • Effect of phosphate separated after adsorption on plant growth. [ABSTRACT FROM AUTHOR]

Terbutaline (TBL, an β-agonists pharmaceuticals) is one of the pharmaceuticals and personal care products (PPCPs), which has caused many environmental concerns due to its eco-toxicological effects in aquatic environment. In this research, density functional theory (DFT) and quantitative structure–activity relationships (QSARs) toxicity methods were performed to systematically elucidate the transformation mechanisms and ecological risk of TBL degraded by •OH and O 3. By analyzing the structure and electronic properties of TBL, the •OH-addition, H-abstraction, single electron transfer and 1, 3-cycloaddition ozonation degradation pathways were mainly investigated. The lowest energy barriers of •OH and O 3 initiated reactions in the degradation process were 7.33 and 18.49 kcal mol−1 respectively, which indicated that the •OH degradation process was more likely to occur than O 3 induced reactions from a thermodynamic perspective. The kinetic rate constants of O 3 and •OH at 298 K were calculated as 7.58 M−1 s−1 and 1.02 × 109 M−1 s−1, respectively. Furthermore, the subsequent intermediates could further transform into hydroxylation substitutes, glyoxylic acid and ketoaldehyde by-products. Based on toxicity assessments, parent reactant TBL can exhibit harmful acute and chronic toxicity to daphnid (identified by LC 50 33.2 mg L−1 and ChV 2.34 mg L−1). The toxicity of most of the degradation products was reduced to harmless level compared with the parent reactant TBL. This work provided a molecular level understanding for evaluating the contribution of O 3 and •OH to the removal of TBL from wastewater by theoretical calculations. [Display omitted] • The degradation mechanisms of terbutaline by.•OH and O 3 in aquatic environment were studied by theoretical calculation methods. • The main degradation mechanism was proposed as an.•OH-addition reaction on the C1 site of aromatic ring of terbutaline. • The calculated total rate constants of.•OH and O 3 -initiated reaction were 1.02 × 109 M−1 s−1 and 7.58 M−1 s−1 during the degradation of terbutaline at 298K. • The eco-toxicity of degradation by-products were changed compared by terbutaline. [ABSTRACT FROM AUTHOR]

Nowadays, the widespread existence and potential adverse effects of emerging micropollutants in waters have prompted the search for effective treatment methods. In this study, the feasibility of UV/O 3 /PMS (peroxymonosulfate, HSO 5 −) method for the elimination of Flutamide (FLU) was comprehensively investigated, with focus on transformation behaviors and risk assessment. The results showed that the UV/O 3 /PMS method has excellent oxidation capability to FLU with the elimination efficiency of 83.7% within 40 min. In addition, the radical (·OH and SO 4 −·) oxidation occupies greater advantages in the initiation reaction pathways of FLU compared to non-radical (O 3 and 1O 2) oxidation. With the participation of H 2 O 2 , H 2 O, O 2 , and ·OH, eleven transformation products (TPs) are generated through hydroxylation, demethylation, and decomposition reactions. According to the risk assessment results, the toxicity of most TPs gradually decreased, but the residual developmental toxicity could not be ignored. Further, the environmental persistence of FLU was evaluated with respect to natural water and advanced oxidation processes. These findings could help to advance the fundamental understanding of emerging micropollutants in the aquatic environments, and provide a basis for their practical application in water treatment. [Display omitted] • The transformation mechanisms involved in UV/O 3 /PMS system were elucidated. • ·OH and SO 4 −· are the major contributors to FLU degradation compared to O 3 and 1O 2. • FLU degradation was caused by hydroxylation, demethylation, and decomposition paths. • UV/O 3 /PMS is a promising treatment method for O 3 or UV-refractory micropollutants. [ABSTRACT FROM AUTHOR]

Reuse of agricultural and industrial wastes simultaneously to prepare hydrochars (HCs) for removal of NH 4 + and PO 4 3− in practical sewage without additional wastes produced is still a challenge. Herein, HCs were fabricated by combination of rape straw and industrial sewage sludge to remove NH 4 + and PO 4 3− from hoggery effluent. Synthesis conditions were firstly optimized and optimized HC (OPT-HC) was further applied to adsorb NH 4 + and PO 4 3−. Monolayer and Pseudo-first-order as well as Pseudo-second-orders were confirmed via adsorption kinetic and isothermal adsorption studies. Morphologies and surface areas of the OPT-HC did not show any transformations before and after adsorption of NH 4 + and PO 4 3−. The OPT-HC after adsorption of NH 4 + and PO 4 3− (OPT–HC–N/P) was further applied as fertilizer for planting Ping-pong Chrysanthemum. Results indicate that the OPT–HC–N/P can improve comprehensive qualities of the Ping-pong Chrysanthemum such as plant height, fresh, Vitamin C, Chlorophyll, soluble protein and sugar because the OPT–HC–N/P can provide extra N and P elements and also promote to release available K in soil. OPT–HC–N/P treated Ping-pong Chrysanthemum open flowers in advance. Thus, two kinds of wastes were re-utilized to remove N and P in real-life effluent. • Agricultural and industrial wastes were used to prepare hydrochars. • The hydrochars can be applied to remove N and P in hoggery effluent. • No wastes produced after removal of N and P. • Horticultural/agricultural applications were further realized. • Qualities of Ping-pong Chrysanthemum improved by HC after adsorption of N and P. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel MM–TCMRs were synthesized for concurrent removal of phosphate and ammonium. • MM–TCMRs exhibits excellent phosphate and ammonium adsorption capacity. • Potential phosphate and ammonium removal mechanism with MM–TCMRs was proposed. • >70 % phosphate and ammonium were recovered from swine wastewater after four cycles. • Nutrient–loaded MM–TCMRs is applied as a fertilizer to promote alfalfa growth. Magnetic magnesium (Mg)–loaded Chinese herbal medicine residues (MM–TCMRs) were fabricated to simultaneously remove and recover phosphate and ammonium from wastewater. The MM–TCMRs exhibited larger specific surfaces and rougher structures with massive spherical particles than those of original residues. They could be separated by adjusting the magnetic field. The phosphate and ammonium adsorption by MM–TCMRs were matched with the pseudo–second–order model, while the Langmuir model yielded the maximum adsorption capacities of 635.35 and 615.57 mg g−1, respectively. Struvite precipitation on the MM–TCMRs surface was the primary removal mechanism with electrostatic attraction, ligand exchange, intra–particle diffusion, and ion exchange also involved. The recyclability of MM–TCMRs confirmed their good structural stability. More importantly, the nutrient–loaded MM–TCMRs enhanced alfalfa growth and improved soil fertility in planting experiments. Collectively, the MM–TCMRs are promising candidates for nutrient removal and recovery from wastewater. [ABSTRACT FROM AUTHOR]

1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane (TBECH), as an emerging brominated flame retardant (EBFR) pollutant, has been often observed in the air, and to comprehend its fate in the environment is still challenging due to the diversity of its stereoisomers. In this work, the environmental transformation behavior and potential toxicological implications of TBECH stereoisomers under the oxidation of OH· in the gas phase were investigated by computational chemistry. Our results indicate the complexity of the TBECH transformation reactions and the diversity of its transformation products in the atmosphere. Although the reactions of TBECH enantiomers with OH· exhibit highly consistency, it is obvious that the reactions of the four diastereoisomers of TBECH with OH· and their subsequent reactions have both specificity and similarity. The dehydrogenation intermediates produced by H-abstraction of OH· in the initial reactions may undergo oxidative debromination, hydroxylation and decomposition reactions, leading to the transformation into low bromine and monohydroxy substituted compounds, as well as debrominated or unbrominated unsaturated fatty ketones. The toxicity assessments show that all transformation products are less toxic to aquatic organisms than TBECH, but some of them are still classified at toxic or harmful levels. More importantly, some transformation products still exhibit carcinogenic and teratogenic activity. To our knowledge, this study provides, for the first time, a deep insight into the transformation mechanism, kinetics, and environmental impacts of atmospheric TBECH by theoretical calculations. [Display omitted] • TBECH can be transformed by OH· in the atmosphere. • The OH-initial reaction of TBECH is favored at low temperatures. • DIMs undergo oxidative debromination, hydroxylation, and decomposition. • Some transformation products are still classified at toxic or harmful levels. • Most of the transformation products exhibit mutagenic activity. [ABSTRACT FROM AUTHOR]

In this paper, density-functional theory (DFT) was employed to investigate the reaction mechanism of SO 2 and NO 2 and the important role of intermediate N 2 O 4 formation. In addition, the effect of pure particulate surface (TiO 2) and particulate surface containing other atmospheric components (H 2 O, NH 3 and SO 4 2−) on the conversion of SO 2 and NO 2 to sulfate also was analyzed. The detailed information that intermediate N 2 O 4 acts as the oxidant was demonstrated in this oxidation reaction of SO 2 and NO 2 (as a rate-determining step). The pure particulate surface (TiO 2) has hardly effect on the oxidation process of SO 2 and N 2 O 4. Whereas, different amounts of H 2 O and NH 3 molecules as well as SO 4 2−, contained on the particulate surface, can effectively reduce the activation energy of oxidation step. And, the optimal process is that SO 2 is oxidized by cis-ONONO 2 with the energy barrier of 4.54 kcal/mol when one NH 3 molecule and one H 2 O molecule are contained on the TiO 2 (101) surface. When more H 2 O molecules are contained on particulate surface, SO 2 tends to form HSO 3 − first. However, HSO 3 − is more difficult to be further oxidized by asy-ONONO 2 than SO 2. This study gains more insight into the contribution of SO 2 and NO 2 to haze and the potential impact of atmospheric constituents (including H 2 O/NH 3 /TiO 2 and SO 4 2−/TiO 2) on the formation sulfate. Image 1 • Asy-ONONO 2 acted as oxidant is easily contained on the particulate surface. • The oxidation of SO 2 and asy-ONONO 2 is easy than HSO 3 −. • The oxidation step of SO 2 and N 2 O 4 is the rate-determining step. • Pure particulate surface has hardly effect on the rate-determining step. • Particulate containing H 2 O, NH 3 and SO 4 2− promote the reaction of SO 2 and N 2 O 4. [ABSTRACT FROM AUTHOR]

The important role of reactive chlorine species (RCS) in electrochemical system has been widely concerned for water disinfection recently. In this study, we built an electrochemical system using carbon nanotube as cathode and oxide precursor (Ti/SnO 2 –Sb 2 O 5 –IrO 2) as anode, where RCS was produced from Cl−. This system was used to degrade nitrogen contaminants, i.e. NO 3 − and 4-nitrophenol. Optimization of the reaction conditions was carried out by a treatment of inorganic nitrogen contaminant NO 3 − and the optimal condition of the electrochemical system was determined at U = 5.5 V, and pH = 10 with a Cl− concentration of 2000 mg L−1, and the removal efficiency of NO 3 − can reach up to 60.6% in 150 min. Under the optimal condition, a common nitrogenous organic pollutant, 4-nitrophenol was treated and a removal efficiency of nearly 100% in 90 min. To investigate the detailed degradation mechanism in the applied electrochemical system, a combined method of products identification and density functional theory (DFT) calculation was employed. It concluded that Cl radicals' generation was stimulated was stimulated by the OH radicals after adding Cl− into the electrochemical system. These two radicals jointly promoted the transformation of 4-nitrophenol resulting in the formation of more toxic organic and inorganic substances. In addition, a conversion of organic nitro group to amino group leading to the formation of 4-aminophenol was found and explained by the indirect reduction theory. Image 1 • 4-Nitrophenol can be converted into NO 3 −, NO 2 −, NH 4 + and other inorganic nitrogen. • Adding chloride ions inhibits the formation of NH 4 + transformed from 4-nitrophenol. • The mechanism of converting a nitro group into an amino group is elucidated. • The toxicity of chlorine-containing transformation products of 4-nitrophenol is enhanced. [ABSTRACT FROM AUTHOR]

Effect of H2O and NH3 on the synergistic oxidation reaction of SO2 and NO2 is investigated by theoretical calculation using the molecule system SO2-2NO2-nH2O (n = 0, 1, 2, 3) and SO2-2NO2-nH2O-mNH3 (n = 0, 1, 2; m = 1, 2). Calculated results show that SO2 is oxidized to SO3 by N2O4 intermediate. The additional H2O in the systems can reduce the energy barrier of oxidation step. The increasing number of H2O molecules in the systems enhances the effect and promotes the production of HONO. When the proportion of H2O to NH3 is 1:1, with NH3 included in the system, the energy barrier is lower than two pure H2O molecules in the oxidation step. The present study indicates that the H2O and NH3 have thermodynamic effects on promoting the oxidation reaction of SO2 and NO2, and NH3 has a more significant role in stabilizing product complexes. In these hydrolysis reactions, nethermost barrier energy (0.29 kcal/mol) can be found in the system SO2-2NO2-H2O. It is obvious that the production of HONO is energetically favorable. A new reaction mechanism about SO2 oxidation in the atmosphere is proposed, which can provide guidance for the further study of aerosol surface reactions. [ABSTRACT FROM AUTHOR]

The disposal of electroplating sludge (ES) is a common concern of researchers. Currently, it is difficult to achieve effective fixation of heavy metals (HMs) using traditional ES treatment. As green and effective HMs removal agents, ionic liquids can be used for the disposal of ES. In this study, 1-butyl-3-methyl-imidazole hydrogen sulphate ([Bmim]HSO 4) and 1-propyl sulphonic acid-3-methyl imidazole hydrogen sulphate ([PrSO 3 Hmim]HSO 4) were used as washing solvents for the removal of Cr, Ni, and Cu from ES. In reaction with increased agent concentration, solid–liquid ratio, and duration, the amount of HMs eliminated from ES rises, whereas opposite patterns were shown in response to rising pH. The quadratic orthogonal regression optimisation analysis also revealed that the ideal washing specifications for [Bmim]HSO 4 were 60 g L−1, 1:40, and 60 min, respectively, for agent concentration, solid–liquid ratio, and washing time, while those for [PrSO 3 Hmim]HSO 4 were 60 g L−1, 1:35, and 60 min, respectively. Under the optimal experimental conditions, the Cr, Ni, and Cu removal efficiencies for [Bmim]HSO 4 were 84.3, 78.6, and 89.7%, respectively, and those values for [PrSO 3 Hmim]HSO 4 were 99.8, 90.1, and 91.3%, respectively. This was mainly attributed to that ionic liquids enhance metal desorption through acid solubilisation, chelation, and electrostatic attraction. Overall, ionic liquids are reliable washing reagents for ES contaminated by HMs. [Display omitted] • Ionic liquids exhibited efficient Cr, Ni and Cu removal from electroplating sludge. • Effect of various experimental conditions on heavy metals removal was explored. • Removal mechanism of ionic liquids to heavy metals was described. • The finding will provide new ideas for the disposal of electroplating sludge. [ABSTRACT FROM AUTHOR]

Hydrometallurgy is the main method to regenerate valuable metals from electroplating sludge and reduce its environmental hazards. As a key step to efficiently recover metals, it is important to choose an environmentally friendly and efficient leaching agent. In this work, four green ionic liquid (ILs) ([BMIm]HSO 4 , [HOOCMIm]HSO 4 , [BSO 3 HMIm]HSO 4 , and [BSO 3 ]Py.HSO 4) were used to leach copper from copper–rich electroplating sludge (C–ES). The tested ILs could effectively leach copper from C–ES, but functionalized ILs have better leaching efficiency, especially sulfonate ILs, which could remove 100% of Cu from C–ES under optimal conditions. Kinetics studies showed that the leaching process of controlled by chemical reaction and material diffusion, and the apparent activation energies were 39.21, 0.98, 14.47, and 41.93 kJ mol−1, respectively. Introducing functional groups (such as carboxyl and sulfonate group) which can complex with metals on cations can enhance the H+ release and complexation ability of ILs, improve the mass transfer efficiency between liquid–solid phase, and thus improve the copper leaching ability by ILs. These findings are of great significance for selecting functional ILs to efficiently regenerate copper and the resource utilization from C–ES. [Display omitted] • An efficient leaching method of copper from electroplating sludge is proposed. • The leaching behavior and the leaching mechanism of copper in ILs was analysed. • Functionalized ILs had better hydrogen release and metal complexation ability. • Sulfonate functionalized ILs is most conducive to copper recovery from C-ES. [ABSTRACT FROM AUTHOR]

The cost–effective removal and recovery of phosphate from wastewater is of great importance to controlling eutrophication and alleviating the phosphorus resource exhaustion crisis. Herein, chitosan (Cs) encapsulated bimetallic lanthanum (La) and iron (Fe) metal(hydro) oxides (La/Fe–Cs) composites were fabricated using a co–precipitated method for enhanced phosphate removal and recovery. The La/Fe–Cs composites had rough and raised spongy–like surfaces coated with La/Fe (hydr)oxide particles with a high specific surface area of 109.84 m2 g−1, providing more potential binding sites for phosphate capture. The La/Fe–Cs composites with a 1:2 La–to–Fe molar ratio exhibited a maximum adsorption capacity of 67.52 mg g−1 for phosphate at 308 K, calculated using the Langmuir model, which was 211% higher than that of monometallic Fe–Cs composites. Meanwhile, this composite also showed a high phosphate removal rate (63–95%) in an extensive applicable pH range (3.00–10.00) and rapid adsorption within 10 min (up to 94%). Moreover, the adsorption of phosphate by La/Fe–Cs composites was mildly disturbed against co–existing ions of NO 3 −, Cl−, and humic acid, while adsorption capacities were reduced by almost 13–45% with the existence of SO 4 2−, HCO 3 −, and CO 3 2−. The FTIR, XPS, and DFT results suggested that La–doped facilitated phosphate removal and the predominant mechanisms involved electrostatic interaction, surface precipitation, and inner–sphere complexation processes. Additionally, La/Fe–Cs composites also illustrated excellent efficiencies in simultaneous scavenging phosphate and ammonia from eutrophication and poultry wastewater. These results highlight bimetallic La/Fe–Cs composites are promising candidates for efficient elimination and recovery of phosphate from real wastewater, and subsequently could be used as slow–release fertilizers or soil amendments. [Display omitted] •Bimetallic La/Fe–Cs composites were synthesized for phosphate removal. • The derived bimetallic La/Fe–Cs composites showed excellent phosphate adsorption capacity of 67.52 mg g−1 • Mechanisms driving phosphates adsorbed onto the La/Fe–Cs composites were elucidated by FTIR, XPS, and DFT. • High efficiency in scavenging phosphate from eutrophication wastewater and poultry wastewater. • The phosphate–loden La/Fe–Cs composites can be used as slow–release fertilizers or soil amendments. [ABSTRACT FROM AUTHOR]

The cost–effective removal and recovery of phosphate from wastewater is of great importance to controlling eutrophication and alleviating the phosphorus resource exhaustion crisis. Herein, chitosan (Cs) encapsulated bimetallic lanthanum (La) and iron (Fe) metal(hydro) oxides (La/Fe–Cs) composites were fabricated using a co–precipitated method for enhanced phosphate removal and recovery. The La/Fe–Cs composites had rough and raised spongy–like surfaces coated with La/Fe (hydr)oxide particles with a high specific surface area of 109.84 m2 g−1, providing more potential binding sites for phosphate capture. The La/Fe–Cs composites with a 1:2 La–to–Fe molar ratio exhibited a maximum adsorption capacity of 67.52 mg g−1 for phosphate at 308 K, calculated using the Langmuir model, which was 211% higher than that of monometallic Fe–Cs composites. Meanwhile, this composite also showed a high phosphate removal rate (63–95%) in an extensive applicable pH range (3.00–10.00) and rapid adsorption within 10 min (up to 94%). Moreover, the adsorption of phosphate by La/Fe–Cs composites was mildly disturbed against co–existing ions of NO 3 −, Cl−, and humic acid, while adsorption capacities were reduced by almost 13–45% with the existence of SO 4 2−, HCO 3 −, and CO 3 2−. The FTIR, XPS, and DFT results suggested that La–doped facilitated phosphate removal and the predominant mechanisms involved electrostatic interaction, surface precipitation, and inner–sphere complexation processes. Additionally, La/Fe–Cs composites also illustrated excellent efficiencies in simultaneous scavenging phosphate and ammonia from eutrophication and poultry wastewater. These results highlight bimetallic La/Fe–Cs composites are promising candidates for efficient elimination and recovery of phosphate from real wastewater, and subsequently could be used as slow–release fertilizers or soil amendments. [Display omitted] •Bimetallic La/Fe–Cs composites were synthesized for phosphate removal. • The derived bimetallic La/Fe–Cs composites showed excellent phosphate adsorption capacity of 67.52 mg g−1 • Mechanisms driving phosphates adsorbed onto the La/Fe–Cs composites were elucidated by FTIR, XPS, and DFT. • High efficiency in scavenging phosphate from eutrophication wastewater and poultry wastewater. • The phosphate–loden La/Fe–Cs composites can be used as slow–release fertilizers or soil amendments. [ABSTRACT FROM AUTHOR]

[Display omitted] • MOFs with a low ratio of H 2 TCPP to monocarboxylate displays the best BPA removal performance. • The contents of O 2 ∙-, 1O 2 and ∙OH are enhanced by high salinity. • Coexisting salt ions increase the density of states near the Fermi level, boosting the transfer of electrons. • Coexisting salt ions prevent the recombination of photogenerated electrons and holes. The treatment of wastewater containing high salinity has been a pressing challenge due to the inhibition of reactive oxygen species by co-existing ions in the actual wastewater. In this work, four Zr 6 O 8 -porphyrinic MOFs (PCN-223, PCN-224, PCN-225, and MOF-525) with different topologies were selected to investigate their performance and mechanisms for the removal of contaminants from hypersaline waters in a visible photocatalytic degradation system. The results showed that the molar ratios of monocarboxylates, ligands, and Zr of the porphyrin-MOFs led to variations in the porosity, pore size distribution, crystal defects, and surface electrical properties of the as-obtained MOFs, resulting in differences in the adsorption and photocatalytic degradation performance of the materials towards bisphenol A. In-situ electron paramagnetic resonance (EPR) and quenching experiments showed that high salt surroundings can significantly increase the levels of O 2 ∙-, 1O 2 and ∙OH in Zr 6 O 8 -porphyrin-MOFs/visible-light systems. DFT calculations explain that the presence of anions not only promotes the adsorption of BPA by MOFs but also facilitates the conduction of photogenerated electrons and prevents the recombination of photogenerated electrons and holes during the photocatalytic process. The super-exchange charge transfer mechanism was shown to play a key role in the Zr 6 O 8 -porphyrin-MOFs/visible-light system, thereby accelerating the degradation of pollutants in high-salinity wastewater. The catalytic system can maintain consistent contaminant degradation efficiency over a wide pH range, with high concentrations of co-existing ions and in real water matrices. In addition, the catalyst also exhibits excellent stability and reusability. This work provides new insights into the application of porphyrin MOFs based visible photocatalytic processes for the treatment of highly saline wastewater. [ABSTRACT FROM AUTHOR]

• Porphyrin-MOF greatly improved its performance in BPF removal under visible light in complex environments. • Photo-generation of ∙OH is enhanced by high salinity in PCN-223/visible-light system. • Possible degradation mechanism and pathway of BPF were proposed. • Toxicity of BPF was reduced in the PCN-223/visible-light system. The efficient degradation of organic contaminants in practical water treatment is a challenge for advanced oxidation processes via such as semiconductor photocatalysis due to interference from the inhibiting influence due to the reactions between radicals and coexisting anions in the actual water column. Herein, a porphyrinic zirconium metal–organic framework (PCN-223) is used in a visible light system to effectively decompose bisphenol F (BPF) in saline water. The PCN-223/visible-light system can effectively resist the influence of environmental coexisting anions and natural organic matter (NOM), thus demonstrating excellent performance in decomposing pollutants. Furthermore, the catalytic system is able to maintain stable contaminant degradation over a wide pH range and in five water matrices. Coexisting anions promote the conductivity of electrons by forming ionic bonds with Zr, which enhances light-induced electron transfer under visible light. This work illustrates the mechanism and conditions under which porphyrin-MOF can resist high salt environments in photocatalysis, and provides a new perspective on the practical application of photocatalysis to overcome complex environmental disturbances. [ABSTRACT FROM AUTHOR]

In recent years, Criegee chemistry has become an important research focus due to its relevance in regulating concentrations of tropospheric OH radicals, hydroperoxides, sulfates, nitrates, and aerosols. However, to date, its interface behavior remains poorly understood. Thus, in this study, we used the Born-Oppenheimer molecular dynamics (BOMD) simulation method to explore the reaction mechanisms between Criegee intermediates (CIs) and methylsulfonic acid (MSA) at the air-water interface, then compared the observed behaviors with those in the gas phase. The addition of Criegee intermediates to MSA is nearly a barrierless reaction and follows a loop-structure mechanism in the gas phase. The high rate constants indicate that the Criegee intermediates and MSA reactions are the main acid removal channels. At the water's surface, the interaction of Criegee intermediates with MSA includes three main channels: 1) direct addition reaction, 2) H 2 O-mediated hydroperoxide formation, and 3) MSA-mediated Criegee hydration. These reaction channels follow a loop-structure or a stepwise mechanism and proceed at the picosecond time-scale. The results of this work broaden our understanding of Criegee atmospheric behaviors in polluted urban and marine areas, which in turn will aid in developing more effective pollution control measures. Unlabelled Image • The ab initio dynamics simulation was adopted to simulate the reactions at the air-water interface. • The reaction of MSA with CH 3 CHOO plays an active role in the MSA removal channel. • At the water's surface, the reaction channels follow a loop-structure or a stepwise mechanism. • MSA also acts as a trigger to promote Criegee hydration at the air-water interface. [ABSTRACT FROM AUTHOR]