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In the treatment of industrial wastewater by electron beam technology, the flocculation process was frequently coupled with electron beam radiation to improve the water quality to meet the discharge standard. Iron-containing coagulant was widely used in the flocculation process. Therefore, this study investigated the impact of residual iron-containing coagulants on pollutant degradation by the ionizing radiation process. Results showed that the absorbed dose required for complete removal of 50 mg/L bisphenol A decreased from 5 kGy to 2.5 kGy in the presence of 100 μM typical iron coagulant (FeCl 3 ). BPA degradation efficiency increased with the increase of FeCl 3 dosage over a wide pH range (3.0-10.0), and the TOC removal efficiency increased from 20% to 45% with the addition of 300 μM Fe(III). The mechanistic investigation demonstrated that • OH was the primary reactive species responsible for BPA degradation. The residual iron coagulants (FeCl 3 ) significantly enhanced the degradation and mineralization efficiency. Under suitable pH conditions (3.0-6.0), the reducing reactive species (e aq ‒ and • H) could effectively reduce Fe(III) to Fe(II), which then reacted with H 2 O 2 , thus inducing in-situ Fenton reaction to generate more • OH, thus promoting the radiolysis degradation of micropollutants. This study explored the potential of using residual iron coagulants from the flocculation process to enhance the performance of electron beam technology for wastewater treatment., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

In this study, the Fe(III)/WS 2 /peroxymonosulfate (PMS) system was found to remove up to 97% of cyclohexanecarboxylic acid (CHA) within 10 min. CHA is a model compound for naphthenic acids (NAs), which are prevalent in petroleum industrial wastewater. The addition of WS 2 effectively activated the Fe(III)/PMS system, significantly enhancing its ability to produce reactive oxidative species (ROS) for the oxidation of CHA. Further experimental results and characterization analyses demonstrated that the metallic element W(IV) in WS 2 could provide electrons for the direct reduction of Fe(III) to Fe(II), thus rapidly activating PMS and initiating a chain redox process to produce ROS (SO 4 •−, •OH, and 1O 2). Repeated tests and practical exploratory experiments indicated that WS 2 exhibited excellent catalytic performance, reusability and anti-interference capacity, achieving efficient degradation of commercial NAs mixtures. Therefore, applying WS 2 to catalyze the Fe(III)/PMS system can overcome speed limitations and facilitate simple, economical engineering applications. [Display omitted] • Fe(III)/WS 2 /PMS system can achieve 97% removel rate of CHA within 10 min. • •OH, SO 4 •−, and 1O 2 are main ROS in the Fe(III)/WS 2 /PMS system. • W(IV) contained in WS 2 can promoting Fe(III)/Fe(II) cycle by providing electrons. • Fe(III)/WS 2 /PMS system can achieve efficient degradation of commercial NAs. • Fe(III)/WS 2 /PMS system exhibits excellent reusability and anti-interference. [ABSTRACT FROM AUTHOR]

The efficiency of the Fenton reaction is markedly contingent upon the operational pH related to iron solubility. Therefore, a heterogeneous Fenton reaction has been developed to function at neutral pH. In the present study, the Bio-Fenton reaction was carried out using magnetite (Fe(II)Fe(III) 2 O 4) and H 2 O 2 generated by a newly isolated H 2 O 2 -producing bacterium, Desemzia sp. strain C1 at pH 6.8 to degrade chloroacetanilide herbicides. The optimal conditions for an efficient Bio-Fenton reaction were 10 mM of lactate, 0.5% (w/v) of magnetite, and resting-cells (O.D. 600 = 1) of strain C1. During the Bio-Fenton reaction, 1.8–2.0 mM of H 2 O 2 was generated by strain C1 and promptly consumed by the Fenton reaction with magnetite, maintaining stable pH conditions. Approximately, 40–50% of the herbicides underwent oxidation through non-specific reactions of •OH, leading to dealkylation, dechlorination, and hydroxylation via hydrogen atom abstraction. These findings will contribute to advancing the Bio-Fenton system for non-specific oxidative degradation of diverse organic pollutants under in-situ environmental conditions with bacteria producing high amount of H 2 O 2 and magnetite under a neutral pH condition. [Display omitted] • H 2 O 2 -producing Desemzia sp. strain C1 was isolated from oil-contaminated soil. • Bio-Fenton reaction was performed using magnetite and H 2 O 2 by strain C1 at pH 6.8. • Optimal conditions for an efficient Bio-Fenton reaction were investigated. • Chloroacetanilide herbicides were chosen as a model of environmental pollutants. • The herbicides were degraded via non-specific oxidative reaction of.•OH. [ABSTRACT FROM AUTHOR]

This study demonstrated the design and fabrication of flower-like Ni/Mn-MOFs materials, and three-dimensional ultrathin flower-like Ni/Mn/MC microspheres were fabricated by embedding metal or metal oxide nanoparticles into a porous carbon skeleton via high-temperature pyrolysis at 600 °C and used for the electrocatalytic degradation of ceftriaxone sodium. This unique ultrathin porous flower-like structure can expose more active sites, provide rapid ion/electron transfer, and improve electrocatalytic activity. Meanwhile, the excellent electrical conductivity of the carbon skeleton, as well as the rational composition and synergistic effect of the two components, can promote the generation of active radicals (•OH and •O 2 −) in the reaction system, which accelerates the electrochemical degradation process and improves the electrocatalytic degradation performance. The results showed that the Ni/Mn/MC-5:1 composite prepared when the molar ratio of Ni: Mn was 5:1 exhibited the best electrocatalytic degradation performance for the degradation of sodium ceftriaxone. The composites showed 98.2% degradation of ceftriaxone sodium in 120 min and maintained sound degradation after 20 cycles. Therefore, we concluded that this novel multicomponent composite has good electrocatalytic activity and stability for the degradation of antibiotic wastewater. [Display omitted] • The incorporation of Mn accelerates the production of.•OH in the reaction system. • The valence transitions of Ni2+/Ni3+ and Mn2+/Mn3+ accelerate the degradation process. • Ni/Mn/MC cathode with excellent electrocatalytic activity and cycling stability. • Ni/Mn/MC cathode realizes efficient degradation of ceftriaxone sodium. [ABSTRACT FROM AUTHOR]

Naphthalene, the most abundant polycyclic aromatic hydrocarbon in the atmosphere, significantly influences OH consumption and secondary organic aerosol (SOA) formation. Naphthoquinone (NQ) is a significant contributor to ring-retaining SOA from naphthalene degradation, impacting the redox properties and toxicity of ambient particles. However, inconsistencies persist regarding concentrations of its isomers, 1,2-NQ and 1,4-NQ. In present work, our theoretical investigation into naphthalene's reaction with OH and subsequent oxygenation unveils their role in SOA formation. The reaction kinetics of initial OH and subsequent O 2 oxidation was extensively studied using high-level quantum chemical methods (DLPNO-CCSD(T)/aug-ccpVQZ//M052x-D3/6–311++G(d,p)) combined with RRKM/master equation simulations. The reactions mainly proceed through electrophilic addition and abstraction from the aromatic ring. The total rate coefficient of naphthalene + OH at 300 K and 1 atm from our calculation (7.2 × 10−12 cm3 molecule−1 s−1) agrees well with previous measurements (∼1 × 10−11 cm3 molecule−1 s−1). The computed branching ratios facilitate accurate product yield determination. The largest yield of 1-hydroxynaphthalen-1-yl radical (add1) producing the major precursor of RO 2 is computed to be 93.8 % in the ambient environment. Our calculated total rate coefficient (5.2 × 10−16 cm3 molecule−1 s−1) for add1 + O 2 closely matches that of limited experimental data (8.0 × 10−16 cm3 molecule−1 s−1). Peroxy radicals (RO 2) generated from add1 + O 2 include 4- cis/trans -(1-hydroxynaphthalen-1-yl)-peroxy radical (add1-4OO add- cis/trans , 66.0 %/17.5 %), 2- cis/trans -(1-hydroxynaphthalen-1-yl)-peroxy radical (add1-2OO add- cis/trans , 10.3 %/6.3 %). Regarding the debated predominance of 1,4-NQ (corresponding to the parent RO 2 , i.e., add1-4OO add- cis/trans) and 1,2-NQ (corresponding to the parent RO 2 , i.e., add1-2OO add- cis/trans) in the atmosphere, our findings substantiate the dominance of 1,4-NQ. This study also indicates potential weakening of 1,4-NQ's dominance due to competition from decomposition reactions of add1-4OO add- cis/trans and add1-2OO add- cis/trans. Precise reaction kinetics data are essential for characterizing SOA transformation derived from naphthalene and assessing their climatic impacts within modeling frameworks. [Display omitted] • The reactions of naphthalene + OH and subsequent O 2 oxidation mainly proceed through addition and abstraction pathways. • The computed total k of OH and subsequent O 2 reaction are 7.2 × 10−12 and 5.2 × 10−16 cm3 molecule−1 s−1 at 300 K, 1 atm. • The add1 (93.8%) and add1-4OO add- cis (66.0%) are the predominant products of naphthalene + OH and subsequent O 2 oxidation. • The formation of 1,4-naphthoquinone (1,4-NQ) is more favorable than that of 1,2-NQ during naphthalene degradation. • The dominant role of 1,4-NQ is weakened due to the competition from the decomposition reactions of 1,4-RO 2 and 1,2- RO 2. [ABSTRACT FROM AUTHOR]

The oxygenation of Fe(II)-bearing minerals for hydroxyl radicals (HO•) formation and contaminant attenuation receives increasing attentions. However, information on dissolved organic matter (DOM) with different types, concentrations, and molecular weights (MWs) in manipulating HO• formation and contaminant attenuation during mineral oxygenation remain unclear. In this study, four iron-pillared montmorillonites (IPMs) and two DOM samples [e.g., humic acids (HA) and fulvic acids (FA)] were prepared to explore the HO• formation and phenanthrene attenuation during the oxygenation of IPMs in the presence or absence of DOMs. Results showed that iron-pillared and high-temperature calcination procedures extended the interlayer domain of IPMs, which provided favorable conditions for a high HO• production from 1293 to 14537 μmol kg−1. The surface-absorbed/low crystalline Fe(Ⅱ) was the predominant Fe(Ⅱ) fractionations for HO• production, and presence of DOMs significantly enhanced the HO• production and phenanthrene attenuation. Moreover, regardless of the types and concentrations, the low MW (LMW, <1 kDa) fraction within DOM pool contributed highest to HO• production and phenanthrene attenuation, followed by the bulk and high MW (HMW-, 1 kDa∼0.45 μm) fractions, and FA exhibited more efficient effects in promoting HO• production and phenanthrene attenuation than HA. The fluorescent spectral analysis further revealed that phenolic-like fluorophores in LMW-fraction were the main substances responsible for the enhanced HO• production and phenanthrene attenuation. The results deepen our understandings toward the behaviors and fate of aquatic HO• and contaminants, and also provide technical guidance for the remediation of contaminated environments. [Display omitted] • Effects of DOM on HO.• formation and contaminant attenuation during IPM oxygenation were studied. • High HO.• production from 1293 to 14537 μmol/kg was observed during IPM oxygenation. • Surface-absorbed/low crystalline Fe(Ⅱ) was the predominant Fe(Ⅱ) species for HO.• production. • Presence of DOM enhanced the HO.• production and phenanthrene attenuation. • Phenolic-like fluorophores in LMW-fraction accounted for the promoting effects. [ABSTRACT FROM AUTHOR]

Bisphenol A (BPA) in seawater tends to be deposited in coastal sediments. However, its degradation under tidal oscillations has not been explored comprehensively. Hydroxyl radicals (·OH) can be generated through Fe cycling under redox oscillations, which have a strong oxidizing capacity. This study focused on the contribution of Fe-mediated production of ·OH in BPA degradation under darkness. The removal of BPA was investigated by reoxygenating six natural coastal sediments, and three redox cycles were applied to prove the sustainability of the process. The importance of low reactivity Fe(II) in the production of ·OH was investigated, specifically, Fe(II) with carbonate and Fe(II) within goethite, hematite and magnetite. The degradation efficiency of BPA during reoxygenation of sediments was 76.78-94.82%, and the contribution of ·OH ranged from 36.74% to 74.51%. The path coefficient of ·OH on BPA degradation reached 0.6985 and the indirect effect of low reactivity Fe(II) on BPA degradation by mediating ·OH production reached 0.5240 obtained via partial least squares path modeling (PLS-PM). This study emphasizes the importance of low reactivity Fe(II) in ·OH production and provides a new perspective for the role of tidal-induced ·OH on the fate of refractory organic pollutants under darkness., Competing Interests: Declaration of competing interest The authors declare no competing financial interest., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The degradation kinetics and mechanism of atrazine (ATZ) via an enzyme-based Fenton reaction were investigated at various substrate concentrations and pH values. Toxicological assessment was conducted on ATZ and its degradation products, and the associated reaction pathway was examined. The in situ production of hydrogen peroxide (H 2 O 2) was monitored within the range of 3–15 mM, depending on the increase in glucose concentration, while decreasing the pH to 3.2–5.1 (initial pH of 5.8) or 6.5–7.4 (initial pH of 7.7). The degradation efficiency of ATZ was approximately 2–3 times higher at an initial pH of 5.8 with lower glucose concentrations than at an initial pH of 7.7 with higher substrate concentrations during the enzyme-based Fenton reaction. The apparent pseudo-first-order rate constant for H 2 O 2 decomposition under various conditions in the presence of ferric citrate was 1.9–6.3 × 10−5 s−1. The •OH concentration ([•OH] ss) during the enzyme-based Fenton reaction was 0.5–4.1 × 10−14 M, and the second-order rate constant for ATZ degradation was 1.5–3.3 × 109 M−1 s−1. ATZ intrinsically hinders the growth and development of Arabidopsis thaliana , and its inhibitory effect is marginal, depending on the reaction time of the enzyme-based Fenton process. The ATZ transformation during this process occurs through dealkylation, hydroxylation, and dechlorination via •OH-mediated reactions. The degradation kinetics, mechanism, and toxicological assessment in the present study could contribute to the development and application of enzyme-based Fenton reactions for in situ pollutant abatement. Moreover, the enzyme-based Fenton reaction could be an environmentally benign and applicable approach for eliminating persistent organic matter, such as herbicides, using diverse H 2 O 2 -producing microbes and ubiquitous ferric iron with organic complexes. [Display omitted] • Enzyme-based Fenton reaction was employed for atrazine (ATZ) elimination. • H 2 O 2 was produced in situ , and its decay rate was quantitatively monitored. • Hydroxyl radicals were steadily produced, which contributed to ATZ removal. • Degradation kinetics at various substrate concentrations and pH were examined. • Degradation pathway and plant toxicity of ATZ and metabolites were assessed. [ABSTRACT FROM AUTHOR]

Metal-based anodes have been used for a long time in the electrochemical oxidation processes to remediate groundwater. However, the high cost of this technique as well as the release of potentially toxic metals (ex, lead), are major barriers being fully implemented. As an alternative of metal-based anodes, in recent years, carbon-based anodes have been paid attention due to their eco-friendliness and cost-effectiveness. This study evaluated the oxidation performance of carbon fiber (CF) anode in a flow-through system. The CF anode degraded 45–87% of the target pollutant (sulfanilamide), depending on the current intensity applied. However, no further degradation of sulfanilamide was observed after the cathode, indicating that sulfanilamide degradation occurred mainly at the anode. This study also determined the effect of electrolytes on electrochemical oxidation using chloride (Cl−), sulfate (SO 4 2−), bicarbonate (CO 3 −), and synthetic groundwater. Cl− and SO 4 2− electrolytes were converted electrochemically into active species, thereby enhancing sulfanilamide degradation, while the bicarbonate and groundwater electrolytes inhibited oxidation performance by scavenging hydroxyl radicals. A series of scavenger tests and characterization showed that the direct oxidation and hydroxyl radicals involved the sulfanilamide degradation. Especially, the production of hydroxyl radicals is more favorable in high currents than in low currents. That is, CF anode contributed to the degradation by direct oxidation of carbon-based electrodes and generation of hydroxyl radicals. In summary, this study highlights how a CF anode is capable of effectively degrading organic pollutants via anodic oxidation. [Display omitted] • CF anode is efficient degradation for sulfanilamide in a groundwater environment. • Anodic reaction is more effective than cathodic reaction in a flow-through reactor. • The production of hydroxyl radicals is determined according to current intensity. • Hydroxyl radicals and oxygenated functional groups were dominant oxidants. [ABSTRACT FROM AUTHOR]

Micro-nano bubble ozonation has been widely applied in the purification of drinking water due to its superior characteristics such as high mass transfer rate and long resistance time. However, its application in groundwater remediation is limited, partially due to the unclear effect of static water pressure on the oxidation efficiency. This study constructed a batch reactor to investigate the influence of static pressure on toluene oxidation by ozone micro-nano bubble water. To achieve constant pressure, weight was added above the mobile reactor roof, and the initial concentrations of toluene and dissolved ozone were 1.00 mg L−1 and 0.68 mg L−1 respectively. Experimental results demonstrated that as the static water pressure increased from 0.0 to 2.5 m, the average microbubble diameter decreased significantly from 62.3 to 36.0 μm. Simultaneously, the oxidation percentage of toluene increased from 40.3% to 58.7%, and the reaction rate between toluene and hydroxyl radical (OH·) increased from 9.3 × 109 to 1.39 × 1010 M−1 s−1, indicating that the shrinkage of micro-nano bubbles generated an abundance of OH· that quickly oxidized toluene adsorbed at the bubble interface. A greater enhancement of oxidation efficiency for nitrobenzene, as compared to p -xylene, was observed after the addition of 2.5 m water pressure, which verified the larger contribution of OH· under static pressure. Although the improvement of oxidation efficiency was reduced under acid and alkaline environments, as well as in practical groundwater matrices, the overall results still demonstrated the promising application of micro-nano bubble ozonation in groundwater remediation. [Display omitted] • Static water pressure of 2.5 m reduced microbubble diameter from 62.3 to 36.0 μm. • k T-OH· increased by 49.5% when static water pressure increased from 0 to 2.5 m. • Additional pressure induced ozone micro-nano bubble shrinkage and OH· generation. • Enhancement of toluene oxidation by OMBW was inhibited in practical groundwater. [ABSTRACT FROM AUTHOR]

Effective water treatment to remove antibiotics and its activity from contaminated water is urgently needed to prevent antibiotic-resistant bacteria (ARB) emergence. In this study, we investigated degradation of Ampicillin (AMP), an extensively used β-lactam antibiotic, using submersible Ultraviolet C Light Emitting Diode (λ max  = 276 nm) irradiation source, and Persulfate (UVC LED/PS system). Pseudo first order rate constant (k obs ) for degradation of AMP (1 ppm) by UVC LED/PS system was determined to be 0.5133 min -1 (PS = 0.2 mM). k obs value at pH 2.5 (0.7259 min -1 ) was found to be higher than pH 6.5 (0.5133 min -1 ) and pH 12 (0.1745 min -1 ). k obs value for degradation of AMP in deionized water spiked with inorganic anions (Cl - =0.5369 min -1 ,SO 4 2- =0.4545 min -1 , NO 3 - =0.1526 min -1 , HCO 3 - ) were presented. Radical scavenging experiment reveal involvement of sulfate radical anion and hydroxyl radical in UVC LED/PS system. EPR analysis confirms the generation of sulfate radical anion and hydroxyl radical. Importantly, 74% reduction of total organic carbon (TOC) occurred within 60 min of AMP treatment by UVC LED/PS system. Seven degradation by-products were identified by high resolution mass spectrometry, and degradation pathways were proposed. Antibacterial activity of AMP towards Bacillus subtilis and Staphylococcus aureus was completely removed after UVC LED/PS treatment. ECOSAR model predicted no very toxic degradation by-products generation by UVC LED/PS system. Electrical Energy per order (EEo) and cost of UVC LED/PS system were determined to be 0.9351 kW/m -1 ), in real tap water (0.1182 min -1 ) and simulated ground water (0.0372 min -1 ) were presented. Radical scavenging experiment reveal involvement of sulfate radical anion and hydroxyl radical in UVC LED/PS system. EPR analysis confirms the generation of sulfate radical anion and hydroxyl radical. Importantly, 74% reduction of total organic carbon (TOC) occurred within 60 min of AMP treatment by UVC LED/PS system. Seven degradation by-products were identified by high resolution mass spectrometry, and degradation pathways were proposed. Antibacterial activity of AMP towards Bacillus subtilis and Staphylococcus aureus was completely removed after UVC LED/PS treatment. ECOSAR model predicted no very toxic degradation by-products generation by UVC LED/PS system. Electrical Energy per order (EEo) and cost of UVC LED/PS system were determined to be 0.9351 kW/m 3 /order and ₹ 7.91/m 3 ($ 0.095/m 3 or € 0.087/m 3 ), respectively. Overall, this study highlights, UVC LED/PS system as energy efficient, low-cost, and its potential to emerge as sulfate radical anion based advanced oxidation process (AOP) to treat water with antibiotics., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

The rapid development of modern agriculture aggravated water eutrophication. Therein, efficient and selective removal of phosphorus in water is the key to alleviating eutrophication. It is well known that lanthanum (La)-based material is a kind of outstanding phosphorus-locking agent. Therefore, improving the property of La-based adsorbents is a hot topic in this field. Herein, novel porous hydroxyl double salts (La/Bi-HDS) with bimetallic capture sites were prepared. The experimental result shows that La/Bi-HDS could maintain the high removal rate in the solution with a higher concentration of competing ions and the maximum P adsorption quantity of La/Bi-HDS attains 168.12 mg/g. Mechanistic studies supported by density functional theory (DFT) calculation demonstrate that introducing Bi 3+ optimizes the electronic structure of La, reducing adsorption energy. In addition, the surface analysis shows that the introduction of Bi, which increases the pore size and volume of the material, improves the utilization efficiency of the active site. In a word, the introduction of Bi element as a strategy of killing two birds with one stone successfully improved the performance of La-based adsorbent. It provided a new direction for developing an efficient phosphorus-locking agent., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

A high oxygen evolution potential (2.6V) and conductivity of Ti/TiO 2 NTs/Ta 2 O 5 -PbO 2 anode was fabricated by mixed metal oxide. A well-aligned TiO 2 nanotubes was successfully prepared by using 1-butyl-3-methylimidazolium tetrafluoroborate as the electrolyte. The surface structure of anodes were characterized by scanning electron microscope, X-ray diffraction and energy dispersive X-ray spectroscopy. During the electrochemical degradation experiments, the effects of different anodes, current density, initial pH value and concentration were discussed. The results showed that co-doped Ta 2 O 5 coating is an effective method to improve the surface morphology and the electrochemical characterization of Ti/TiO 2 NTs/PbO 2. At the initial pH value of 3 and current density of 12 mA cm−2, the removal rates of Acid Orange 7 and total organic carbon with Ti/TiO 2 NTs/Ta 2 O 5 -PbO 2 anode were almost 100% and 98.3%. Comparing with Ti/PbO 2 anode at the same charge consumption (3 A h L−1), the instantaneous current efficiency of the Ti/TiO 2 NTs/Ta 2 O 5 -PbO 2 anode and Ti/TiO 2 NTs/PbO 2 anode increased by 40.0% and 27.1%, respectively. The highest rate of k.OH on Ti/TiO 2 NTs/Ta 2 O 5 -PbO 2 anode was 12.4 μmol (L min)−1. The organic dyes are oxidized into CO 2 and H 2 O by .OH radical. The reaction process and mechanism during the electrochemical degradation were discussed. Image 1 • High oxygen evolution potential and conductivity of Ti/TiO2 NTs/Ta2O5-PbO2 anode. • A well-aligned TiO2nanotubes were prepared by using ionic liquids. • Co-doped Ta2O5can improve the surface morphology and electrochemical characterization. • The removal rates of AO 7 and TOC with Ti/TiO2 NTs/Ta2O5-PbO2anode were 100% and 98.3%. • The electrochemical degradation process and mechanism of dye are proposed. [ABSTRACT FROM AUTHOR]

The transformation of roxarsone (ROX) during UV disinfection with Fe(III) has been investigated. Fe(OH)2+, as the main Fe(III) species at pH = 3, produces HO under UV irradiation leading to the oxidation of ROX. Dissolved oxygen plays a very important role in the continuous conversion of generated Fe2+ to Fe3+, which ensures a Fe(III)-Fe(II) cycle in the system. The presence of Cl−/HCO 3 −/NO 3 − has little influence on the ROX transformation, whereas PO 4 3− achieves an obvious inhibitory effect. The transformation of ROX leads to the formation of inorganic arsenic consisting of a much higher amount of As(V) than As(III). LC-MS analysis shows that phenol, o -nitrophenol and arsenic acid were the main transformation products. Both the radical scavenger experiment and electron spin resonance data confirm that the HO is responsible for ROX transformation. The toxic transformation products are found to have potential environmental risks for the natural environment, organisms and human beings. Image 1 • Roxarsone was effectively transformed during UV disinfection in the presence of Fe3+. • PO 4 3− showed obvious inhibition effect on the roxarsone transformation. • Hydroxyl radical was responsible for the transformation of roxarsone. • The disinfection byproducts were found to have potential environmental risks. [ABSTRACT FROM AUTHOR]

The carbonized waste printed circuit board (c-PCB) was used as novel copper-based catalyst for Fenton-like discoloration of Rhodamine B (RhB). The elemental ingredients, structure and morphology of the catalyst was investigated by multi-techniques. The catalytic activity of c-PCB for RhB discoloration was evaluated in the presence of H 2 O 2 , examining the factors of catalyst dosage, H 2 O 2 dosage, solution pH, RhB concentration and temperature. RhB discoloration is improved with increasing catalyst dosage (0–2.0 g L−1), H 2 O 2 dosage (0–0.15 mol L−1), solution pH (4.66–9.36) and temperature (30–50 °C). We found that c-PCB shows excellent catalytic activity for RhB discoloration in a broad pH range. RhB removal of 95.78% is obtained within 6 h at neutral pH (6.70). RhB discoloration is well described by the first-order kinetics, and the activation energy is calculated to be 87 kJ mol−1. The dominant role of OH radical in the c-PCB/H 2 O 2 system is identified by quenching tests. The plausible pathway for RhB discoloration is discussed based on the time-dependent UV–vis spectra. The possible catalytic mechanism in the c-PCB/H 2 O 2 system is also presented. Good reusability of c-PCB is verified by three cycles. This work opens a new strategy of "waste treating waste", facilitating management of hazardous solid wastes and cleaner treatment of textile wastewater. Image 1 • Fenton-like discoloration of Rhodamine B was conducted by a novel catalyst. • RhB discoloration depends on catalyst dosage, H 2 O 2 dosage, pH and temperature. • The catalyst significantly improves RhB discoloration via Fenton-like reaction. • The dominant role of OH radical is verified in catalytic system. • A plausible mechanism for catalytic discoloration of RhB is proposed. [ABSTRACT FROM AUTHOR]

The homogeneous Fe(VI)/Na 2 SO 3 system has been proposed for highly efficient degradation of recalcitrant contaminants, in which sulfite could significantly enhance the transformation of organic substrate by Fe(VI). Also, the Fe(VI)/NaHSO 3 system could show high efficiency across a wide range of pH conditions. The degradation rates reached up to 80% within 2 min and 70% within 5 min in strongly acidic and alkaline conditions, respectively. Unexpectedly, a faster removal rate was obtained in Fe(VI)/NaHSO 3 system than that in Fe(VI)/Na 2 SO 3 system for the degradation of methylene blue (MB). A reasonable dye degradation mechanism was proposed and verified by a series of experiments. The high oxidation potential of Fe(VI) and other species such as sulfate and hydroxyl radicals were responsible for the outstanding capabilities of Fe(VI)/NaHSO 3 system, which could significantly improve the treatment of organics in wastewater under a very wide range of pH conditions. Image 1 • Homogeneous Fe(VI)/Na 2 SO 3 system was developed for degradation of contaminants. • Sulfite significantly enhanced the transformation of organic substrate by Fe(VI). • The Fe(VI)/NaHSO 3 system could show high efficiency across a wide range of pH. • Dye degradation rates reached up to 80% within 2 min in strongly acidic conditions. [ABSTRACT FROM AUTHOR]

Organic degradation by zero-valent metal (ZVM)-activated peroxymonosulfate (PMS) systems has drawn great attention in water treatment. Among various types of ZVM, zero-valent copper (ZVC) showed greatest activating capacity. However, the disadvantages of the released Cu2+ limit the practical utilization of ZVC. In this study, the activation capacity of four normal-sized copper catalysts, namely, copper sheet, graphene-copper sheet, copper foam, and graphene-copper foam, for PMS was investigated using Naproxen (NPX) as the probe compound. Results showed that the degradation efficiency of NPX increased by 10%, while the release of Cu2+ decreased by 30% by coating the copper with graphene. Stability tests showed that all of the four catalysts exhibited considerable stability in PMS activation. Furthermore, we found for the first time that the hydroxyl radical was the dominant species in the degradation of NPX rather than the sulfate radical, which was proved by ESR and radical scavenging experiments. Finally, six intermediates were identified by HPLC-MS/MS, and the degradation pathways were proposed. This study confirmed the feasibility of graphene coating on metals to achieve the enhancement of PMS activation. • The activation capacity of four types of normal-sized zero-valent copper catalyst on PMS was investigated. • The release of copper ions could be inhibited by graphene coating, while the degradation efficiencies of NPX increased. • PMS acted as an electron acceptor in the four copper-catalyzed PMS systems. • Hydroxyl radical was the dominant species in the degradation of NPX, and water acted as the radical precursor. [ABSTRACT FROM AUTHOR]

Abstract The degradation of aniline solution using the dielectric barrier discharge (DBD) plasma was studied in this paper. The results indicated that the initial concentration of aniline, applied voltage and initial pH value affected the removal efficiency of aniline significantly. After 12 min with DBD plasma treatment, 90.2% removal efficiency was achieved at aniline concentration of 100 mg L−1 with an applied voltage of 3.0 kV and pH 8.43. The removal efficiency decreased with the presence of radical scavengers, indicating that hydroxyl radical plays a key role in the degradation process. The removal efficiency increased obviously when Fe2+ was added. Additionally, the intermediate products generated in the degradation process of aniline were analyzed by some analytical techniques, including total organic carbon analysis, ultraviolet-visible spectroscopy, Fourier Transform Infrared spectroscopy, Gas Chromatography-Mass Spectrometer, etc. The results showed that the degradation of aniline was mainly due to the strong oxidizing capacity of hydroxyl radical produced by the DBD plasma system. Based on the intermediate products identified in the study, the possible degradation mechanism and pathways were proposed. Graphical abstract Image 1 Highlights • Atmospheric-pressure DBD plasma can degrade aniline effectively. • The effect of different parameters on aniline degradation was studied. • The intermediates products formed during the DBD plasma treatment were detected. • The degradation pathways of aniline were proposed. [ABSTRACT FROM AUTHOR]

Abstract Chloral hydrate (CH) is a common disinfection by-product found in treated water, and its effective control is important to human health. This study evaluated the effects of some environmental factors (e.g., pH, CH dosage, typical ions) and operational variables (e.g., lamp power, irradiation time) on CH photolysis efficiency via low-pressure mercury lamp–induced ultraviolet (LPUV) at 254 nm. The results demonstrated that the photolysis rate increased significantly with increasing pH from 7.0 to 10.5 and lamp power from 6 to 12 W. Meanwhile, the presence of nitrate, iodide, or free chlorine facilitated CH photolysis, whereas the existence of natural organic matter hindered the process. Together, these factors may help explain varying CH photolysis in different types of waters: seawater > ultrapure water > tap water > lake water. In addition, the initial CH dosage also played an important role, with higher CH being degraded more slowly. Mechanistically, although no catalyst or oxidant was added, CH photolysis was to some extent inhibited by a hydroxyl radical quencher, tert -butyl alcohol, suggesting that indirect photolysis was also responsible for CH loss. In terms of reaction products, the CH photolysis yielded primarily chloride ions and carbon dioxide, thus supporting mineralization as the key pathway. The results may help better understand the control of CH in water using UV. Graphical abstract Image 1 Highlights • Factors affecting chloral hydrate (CH) photolysis by UV254 were evaluated. • CH photolysis increased with higher pH & lamp power but lower concentration (C 0). • Both direct photolysis and indirect photolysis were responsible for the CH loss. • CH photolysis yielded chloride ions and carbon dioxide as key products. [ABSTRACT FROM AUTHOR]

Abstract Diclofenac sodium (DCF) is frequently detected as a non-steroidal pharmaceutical in the aquatic environment. In this study, the degradation of DCF in two heterogeneous systems, pre-magnetization Fe0/H 2 O 2 (Pre-Fe0/H 2 O 2) and Fe0/H 2 O 2 system, was comparably studied. Our findings proved that Pre-Fe0 could significantly improve the degradation and dechlorination of DCF due to the change of Fe0 characteristics after pre-magnetization. Compared with Fe0/H 2 O 2 process, Pre-Fe0/H 2 O 2 process has 2.1–7.0 times higher rate constant for DCF degradation at different H 2 O 2 dosages (0.25–2.0 mM), initial pH (3.0–6.0) and Fe0 dosages (0.25–1.5 mM). The characterizations by X-ray Photoelectron Spectroscopy and Electron Paramagnetic Resonance confirmed that the enhancement attributed to the increase of Fe0 corrosion and fast generation of OH. In addition, preliminary degradation mechanism was elucidated by major products identification using UPLC-MS, through which the degradation intermediates, such as 4-hydroxy-diclofenac or 5-hydroxydiclofenac, 2,6-dichloroaniline, phenylacetic acid, 1,3-dichlorobenzene and 2-aminophenylacetic acid were identified. Hydroxylation, decarboxylation, C N bond cleavage and ring-opening involving the attack of OH or other substances, were the main degradation mechanism. Therefore, Pre-Fe0/H 2 O 2 process, which does not need extra energy and costly reagents, is an efficient and environmental-friendly process to degrade DCF. Highlights • Pre-Fe0/H 2 O 2 enhanced DCF degradation rate 2.1–7.0 times and reduced regent dosage. • The increase of corrosion of Fe0 and fast generation of OH in Pre-Fe0/H 2 O 2 system. • Possible DCF degradation mechanism by Pre-Fe0/H 2 O 2 was suggested. • Pre-Fe0/H 2 O 2 process is a more cost-effective process to degrade DCF. [ABSTRACT FROM AUTHOR]

Abstract Self-enhanced ozonation is a new approach for generation of hydroxyl radicals at low pH. Unfortunately at acidic environment chloride effectively scavenges the radicals. Therefore, the presence of chloride in ozonated medium would be detrimental for the most of the process practical applications. In self-enhanced ozonation process almost complete degradation of aromatics is observed during first 10min. Addition of 3.22 mM of chloride completely hinders degradation of nitrobenzene (NB) or benzoic acid (BA). This work shows that the scavenging effect of chlorides may be overcome with an excess of phosphate. Addition of 50 mM of phosphates to ozonated water brings back 74% removal of NB or 87% of BA, when 24 μM of compound is ozonated in the presence of 3.22 mM chloride during 60min. The excess of phosphate sufficient to overcome the scavenging activity of chloride in the self-enhanced ozonation of aromatic compounds at acidic pH is much lower than that implied by the reaction rates of both ions with hydroxyl radicals. To the best of our knowledge the recovering effect of phosphate has not been shown before. Graphical abstract Image 1 Highlights • Self-enhanced ozonation at low pH is confirmed for nitrobenzene. • Chloride ions strongly hinder organics removal in self-enhanced ozonation processes. • Presence of phosphates can overcome inhibiting effect of chlorides. • Recovered self-enhanced ozonation in the presence of chlorides is of radical nature. • Phosphate-recovered reactions are slower than those in the absence of chlorides. [ABSTRACT FROM AUTHOR]

N -containing organophosphonate antiscalants such as Aminotris (methylene phosphonic acid) (NTMP/ATMP) and Diethylenetriamine penta(methylene phosphonic acid) (DTPMP) are commonly used in reverse osmosis (RO) to prevent scaling, as well as to increase permeate yields. However, the concentrate in RO still contains antiscalants which can cause adverse effects in the environment such as mobilization of heavy metals. The abatement of antiscalants from RO concentrate can promote the precipitation of oversaturated scale-forming substances and reduce the risk of adverse environmental effects. In the present study, the degradation of NTMP and DTPMP as representatives for N -containing organophosphonate by ozone, hydroxyl radicals (•OH), and sulfate radicals (SO 4 •-) are studied regarding reaction kinetics and degradation in different matrices. The results show that NTMP and DTPMP react fast with ozone and sulfate radicals (formed in UV/persulfate). Reaction rate constants of ozone showed a strong pH dependency due to the dissociation of the amine. The apparent reaction rates for pH 7 have been determined to be k app (NTMP + ozone) = 1.44 × 105 M−1 s−1 and k app (DTPMP + ozone) = 1.16 × 106 M−1 s−1. Reaction kinetics of •OH and SO 4 •- did not play a distinctive pH dependency (k (•OH) = 109-1010 M−1 s−1 and k (SO 4 •-) = 107-108 M−1 s−1). Furthermore, real water experiments have shown that ozonation and UV/persulfate are effective tools to abate organophosphonates in RO concentrates. The formation of carcinogenic bromate in ozonation is minimized by the presence of N -containing organophosphonates presumably due to enhanced ozone consumption and scavenging of free bromine. [Display omitted] • Ozonation is a promising tool for organophosphonate removal in reverse osmosis concentrates. • N -containing organophosphonates mitigate bromate formation. • Radical based processes are less efficient than ozonation. [ABSTRACT FROM AUTHOR]

Flow-through heterogeneous electro-Fenton (FHEF) process shows a broad prospect for refractory organic pollutants removal. However, maintaining a long-term service life of higher catalytic cathode is crucial for the development of cathode materials, especially for iron-functionalized cathode operated under harsh conditions. In this study, a novel bimetallic CC@FeOCl–Cu composite was synthesized through one-step calcination, coupled with a series of microstructure characterization methodology, including XRD, SEM-EDS, XPS, and FTIR. The superior catalytic activity of CC@FeOCl–Cu could be ascribed to Fe–Cu synergy and better dispersion of FeOCl nanosheets. With the optimal Cu:Fe ratio of 1:60, the bifunctional ACF/CC@FeOCl–Cu cathode was employed in FHEF process, exhibiting an outstanding performance for sulfamethoxazole (SMX) removal over a wide pH range (3.0–9.0). Comparison of experimental results indicated that the ACF/CC@FeOCl–Cu-FHEF process showed higher performance than ACF/CC@FeOCl-FHEF and homogeneous EF processes. The average SMX removal efficiency was 98% and TOC removal efficiency was more than 57% even after 10 cycles. Radical quenching experiments and electron spin resonance test confirmed that •OH was the primary active species. More •OH was generated in the ACF/CC@FeOCl–Cu-FHEF process because the doping of Cu could enhance catalytic activity of cathode. In addition, the satisfactory performance could be observed in the ACF/CC@FeOCl–Cu-FHEF process for the treatment of real landfill leachate, indicating its potential for practical application in wastewater treatment. [Display omitted] • Bimetallic CC@FeOCl–Cu were synthesized by a one-step calcination method. • Excellent SMX removal was achieved in ACF/CC@FeOCl–Cu-FHEF process. • ACF/CC@FeOCl–Cu cathode exhibited excellent reusability and stability. • Synergistic interaction between Fe and Cu accelerated the generation of •OH. • The practicability of ACF/CC@FeOCl–Cu-FHEF process was also analyzed. [ABSTRACT FROM AUTHOR]

Combination of microbial fuel cell (MFC) and advanced oxidation process (AOP) is promising for pollutant removal. In this paper, Cu0-loaded carbon cloth cathode by electrodeposition (Cu@CC-PS-MFC) was applied to enhance 2,4-dichlorophenol (2,4-DCP) degradation based on persulfate (PS) activation in microbial fuel cell. Cu0 exhibited a typical structure of face-centered cubic metal polyhedron on carbon cloth. The removal of 2,4-DCP by Cu@CC-PS-MFC (75.6%) was enhanced by more than 50% compared to CC-PS-MFC (49.2%) after 1 h of reaction. 30 mg/L 2,4-DCP in Cu@CC-PS-MFC was completely removed and achieved a high mineralization (80.6%) after 9 h of reaction under optimized condition with low dissolved copper ion concentration (0.615 mg/L). Meanwhile, more than 90% removal of 2,4-DCP was stably achieved with flow operation condition (hydraulic residence time of 7.2 h). The change of copper valent state Cu0/Cu 2 O/CuO was the main mechanism of PS activation with main reactive species of O • H and O 2 1. The bioanode of MFC enhanced the in-situ regeneration of ≡Cu+ and ≡Cu0 on the catalyst surface by transporting electrons, which was believed to contribute to good catalyst lifetime and excellent 2,4-DCP removal. Electrodeposited copper contributes to the enhanced degradation of 2,4-DCP with energy recovery at the same time which can further broaden the application MFC. [Display omitted] • Cu0-loaded cathode enhanced 2,4-DCP degradation in PS-based MFC. • Bioelectricity drove catalyst regeneration and improved catalyst life. • O • H and O 2 1 dominated degradation of 2,4-DCP with no pH adjustment. [ABSTRACT FROM AUTHOR]

The present article describes the recent advancements (since 2018) in peroxicoagulation (PC) process, which was introduced by Professor Enric Brillas and his group in 1997. Instead of checking the efficiency of PC process to degrade a targeted pollutant in synthetic wastewater, researchers started testing its efficacy for the treatment of complex real wastewater. Applications like disinfection and removal of heavy metals as well as oxidative removal of arsenite from water were tested recently. To improve the efficiency of PC process, modifications were made for electrode materials (both anode and cathode) and electrolytic cells. Performance of PC process in combination with other treatment technologies is also discussed. [Display omitted] • Recent advances in PC process were elaborated. • Mechanisms of ferryl ion formation were discussed. • Emerging applications such as disinfection and inorganic ion removal were detailed. • Different electrode modifications and cell modifications were explained. • Efficacy of PC process in combination with other process was examined. [ABSTRACT FROM AUTHOR]

Fenton-based electrochemical processes (FEPs) using newly engineered 3D photocatalyst nanocomposites have garnered significant attention owing to their ability to remove emerging contaminants. Despite the development of numerous materials, there is still a need to enhance their efficiency, stability, and recyclability to address the limitations of FEPs. This study seeks to address this issue by investigating sustainable methods to engineer novel 3D core-shell photocatalyst composites for application in FEPs. These materials can update the photo-assisted FEPs activity, and magnetism can be helpful for the easy recyclability of the catalyst. Herein, we successfully synthesized a magnetic and photoactive CuFe 2 O 4 @MIL-100(Fe) (CM) composite through sustainable methods and assessed its morphological structure and physicochemical and photocatalytic properties. The catalytic performance of CM was investigated in an undivided RuO 2 /air-diffusion cell to treat Cefadroxil. The results show that heterogeneous photoelectro-Fenton (HPEF) (100% in 120 min) has higher degradation efficiency than electro-Fenton (100% in 210 min) and electrooxidation (73.3% in 300 min) processes. The superior degradation efficiency of HPEF is attributed to the formation of a large amount of hydroxyl radicals indicating the excellent photocatalytic activity of the material due to the direct excitation of the Fe–O cluster, which boosts the redox reaction of Fe2+/Fe3+. Key operational parameters such as pH, catalyst concentration, current density, and CuFe 2 O 4 proportion on MIL-100(Fe) in the composite were optimized in the HPEF process. The optimized composite exhibited good stability and easy recyclability, allowing high removal efficiency, which can be kept up after five cycles of 90 min. High degradation performance was observed using natural sunlight radiations. Additionally, possible catalytic degradation mechanisms in HPEFs were proposed based on radical quenching experiments. This study has significant potential to contribute to the development of more sustainable and effective water treatment strategies. [Display omitted] • CuFe 2 O 4 @MIL-100(Fe) successfully prepared as highly active photocatalyst. • The composite showed excellent UV and solar photocatalyst performance. • CuFe 2 O 4 @MIL-100(Fe) maintained high catalytic activity in the pH range 3.0–9.0. • Photogenerated electron allowed catalyst regeneration and provide additional.·OH. • Magnetic CuFe 2 O 4 @MIL-100(Fe) exhibited good stability and easy recyclability. [ABSTRACT FROM AUTHOR]

Paroxetine (abbreviated as PXT) has been widely used as one of the standard antidepressants for the treatment of depression. PXT has been detected in the aqueous environment. However, the photodegradation mechanism of PXT remains unclear. The present study aimed to use density functional theory and time-dependent density functional theory to study the photodegradation process of two dissociated forms of PXT in water. The main mechanisms include direct and indirect photodegradation via reaction with ·OH and 1O 2 and photodegradation mediated by the metal ion Mg2+. Based on the calculations, PXT and PXT-Mg2+ complexes in water are photodegraded mainly indirectly and directly. It was found that PXT and PXT-Mg2+ complexes were photodegraded by H-abstraction, OH-addition and F-substitution. The main reaction of PXT indirect photolysis is OH-addition reaction, while the main reaction of PXT0-Mg2+ complex is H-abstraction. All the reaction pathways of H-abstraction, OH-addition and F-substitution are exothermic. PXT0 reacts more readily with ·OH or 1O 2 in water than PXT+. However, the higher activation energy of PXT with 1O 2 indicates that the 1O 2 reaction plays a minor role in the photodegradation pathway. The direct photolysis process of PXT includes ether bond cleavage, defluorination, and dioxolane ring-opening reaction. In the PXT-Mg2+ complex, the direct photolysis process occurs via a dioxolane ring opening. Additionally, Mg2+ in water has a dual effect on the direct and indirect photolysis of PXT. In other words, Mg2+ can inhibit or promote their photolytic reactions. Overall, PXT in natural water mainly undergo direct and indirect photolysis reactions with ·OH. The main products include direct photodegradation products, hydroxyl addition products and F-substitution products. These findings provide critical information for predicting the environmental behavior and transformation of antidepressants. [Display omitted] • The direct photolysis of PXT has three different reaction types in water. • Ring-opening of dioxolane was the direct photolysis pathway of PXT-Mg2+ complex. • The photolysis of PXT with ·OH is H-abstraction, OH-addition and F-substitution. • Mg2+ can inhibit or promote the direct and indirect photolysis of PXT. • 1O 2 plays a secondary role in the photodegradation of PXT. [ABSTRACT FROM AUTHOR]

The removal of three antibiotics i.e., metronidazole (MNZ), ciprofloxacin (CIP) and tetracycline (TET), from aqueous system via TiO 2 photocatalysis under UV-A light was investigated. Photocatalyst(s) were prepared using sol-gel method under different calcination temperatures (400-800 °C) and water-alcohol ratio. The spherical shaped catalyst (mean particle size ∼ 61 nm) was characterized via FTIR, XRD, BET, SEM, Raman, XPS, UV-DRS, and Fluorometry, and point of zero charge was also determined (pH PZC  ∼ 6.6). Batch photo-catalytic degradation studies have shown complete degradation of MNZ, CIP and TET after 50, 75 and 20 min with a TOC removal of 37%, 44% and 31%, respectively. The activity of sol-gel prepared TiO 2 was comparatively higher than commercially available pure anatase TiO 2 nanoparticles due to lesser mean particle size. The ratio of water to alcohol in the preparation of TiO 2 catalyst was found to have significant effect on antibiotic removal. Moreover, persulfate (PS) addition of 0.1 g/L amplified the pseudo-first-order removal-rate constant by 2.75, 3.3 and 1.6 times for MNZ, CIP and TET, respectively. The higher initial pH values (8 and 10) have shown the best removal efficiency for all antibiotics. Subsequently, central composite design (CCD) experiments were conducted under multi-antibiotic conditions. Near complete removal of all antibiotics were observed within 120 min. Scavenging studies revealed that hydroxyl and superoxide radicals play major roles in photo-catalytic degradation of MNZ, CIP and TET. During photocatalysis, MNZ degradation was initiated by hydroxylation reaction, CIP by piperazine ring opening by hydroxyl attack and TET by multiple hydroxylation process. Overall, TiO 2 showed good efficiency at degrading multiple antibiotics and has the potential for practical application on a larger scale., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Sulfate radical (SO 4 •- )-based advanced oxidation processes (AOPs) have become promising alternatives in environmental remediation due to the higher redox potential (2.6-3.1 V) and longer half-life period (30-40 μs) of sulfate radicals compared with many other radicals such as hydroxyl radicals (•OH). The generation and mechanisms of SO 4 •- and the applications of SO 4 •- -AOPs have been examined extensively, while those using sulfite as activation precursor and their comparisons among various activation precursors have rarely reviewed comprehensively. In this article, the latest progresses in SO 4 •- -AOPs were comprehensively reviewed and commented on. First of all, the generation of SO 4 •- was summarized via the two activation methods using various oxidant precursors, and the generation mechanisms were also presented, which provides a reference for guiding researchers to better select two precursors. Secondly, the reaction mechanisms of SO 4 •- were reviewed for organic pollutant degradation, and the reactivity was systematically compared between SO 4 •- and •OH. Thirdly, methods for SO 4 •- detection were reviewed which include quantitative and qualitative ones, over which current controversies were discussed. Fourthly, the applications of SO 4 •- -AOPs in various environmental remediation were summarized, and the advantages, challenges, and prospects were also commented. At last, future research needs for SO 4 •- -AOPs were also proposed consequently. This review could lead to better understanding and applications of SO 4 •- -AOPs in environmental remediations., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Owing to its inertness toward refractory organic pollutants and the release of Mn 2+ , the use of permanganate was limited in soil and groundwater remediation. The present study proposed an improvement strategy based on glucose-derived carbonaceous materials, which enhanced the potential of permanganate degrading organic pollutants. The glucose-derived carbonaceous material with 1000 °C charring temperature was named C1000, which was exploited in activating KMnO 4 for the elimination of refractory organic contaminants. The addition of C1000 in the KMnO 4 system triggered the degradation of refractory p-nitrophenol and quicken phenol degradation. Unlike the detection of Mn(III) species in a solo KMnO 4 system, the presence of C1000 facilitated the formation of • OH in the KMnO 4 system, which was confirmed by the use of quenchers such as methanol, benzoic acid, tertiary butanol, and carbonate. Additionally, the glucose-derived carbonaceous material played multiple roles in improving the performance of permanganate, including the enrichment of organic pollutants, donation of electrons to permanganate, and acting as an electron shuttle to facilitate the oxidation of organic pollutants by permanganate. The study's novel findings have the potential to expand the use of permanganate in the remediation of organic pollutants., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Abstract Naphthenic acids (NAs) are one of the constituents of concerns in oil sands process water (OSPW) because of their persistence and recalcitrance. Herein, we investigated the degradation of five model NA compounds by UV-activated persulfate (UV/persulfate) process under medium-pressure UV lamp irradiation at pH 8.0. UV/persulfate process showed higher degradation efficiency towards cyclohexanoic acid (CHA) compared to UV/H 2 O 2 process under the same experimental conditions. CHA (0.39 mM) was completely removed within 30 min when 2 mM persulfate was used as oxidant, while more than 60 min were needed for the UV/H 2 O 2 process. The removal of CHA decreased from 100% to 10% when 300 mM tert-butyl alcohol (TBA) was used as the scavenger, indicating that hydroxyl radical (OH) was responsible for the CHA degradation in the UV/persulfate process. Sulfate (SO 4 −) radicals reacted slowly with CHA in the UV/persulfate process with a second-order rate constant of k = 5.3 × 107 M−1s−1. Relative kinetics studies using binary mixtures of model NA compounds showed similar structure-reactivity to that under UV/H 2 O 2 process. NAs with long carbon chain, cyclic ring, and aromatic ring were more reactive in the UV/persulfate process. The presence of high concentration of chloride ions dramatically inhibited the reaction. The OH radicals in the UV/persulfate process were generated by capturing OH− in solutions, as evidenced by the decrease of the pH value from 8.0 to 2.8 before and after treatment, respectively, in a pure water matrix. Primary intermediate products (oxy-CHA, hydroxyl-CHA, and dihydroxyl-CHA) of UV/persulfate process were confirmed by UPLC-MS. Highlights • UV activated persulfate oxidation process was used for the degradation of model NAs. • SO 4 − radical reacted slowly with CHA in UV/persulfate process compared to BA. • OH generated from SO 4 − and OH− were the main radicals responsible for the CHA removal. • Relative kinetics of model NA compounds in UV/persulfate process were studied. • The presence of chlorine ions was adverse to CHA removal and related chlorinated by-products were formed. [ABSTRACT FROM AUTHOR]

Abstract Norfloxacin is a synthetic antibiotics drug which is widely used in the treatment of infectious diseases and also often carelessly released into natural environment resulting in antibiotics-contaminated wastewater. In this work, we employed atmospheric-pressure non-thermal dielectric barrier discharge (DBD) to treat norfloxacin-contaminated water and investigated the degradation efficiency and mechanism for the plasma treatments under different conditions with varied working gas atmospheres. Our results showed that the DBD efficiency for norfloxacin degradation depended on reactive oxygen/nitrogen species (RONS) produced in the plasma treatment, while the plasma-induced hydroxyl radical played a critical role in the norfloxacin degradation. For O 2 -DBD, except for the contribution from reactive oxygen species (ROS), ozone could also play an important role. For N 2 -DBD, reactive nitrogen species (RNS) could work synergistically with H 2 O 2 to enhance the degradation effect. We also checked the plasma activated liquid (PAL) effect and analyzed the degradation products so that the degradation mechanism and pathways could be elucidated. This work may therefore provide the guidance for effective and feasible application of low-temperature plasma technology in treatment of antibiotics-contaminated wastewater. Graphical abstract Image 1 Highlights • Atmospheric-pressure DBD can degrade norfloxacin effectively. • O 2 -DBD and air-DBD showed higher degradation efficiency than N 2 -DBD. • N 2 -DBD with H 2 O 2 improved degradation efficiency significantly. • Both the transient and non-direct PAL effect were observed and distinguished. • Roles of RONS were investigated with degradation pathways and mechanism clarified. [ABSTRACT FROM AUTHOR]

In this study, the TiO 2 -mediated photocatalytic removal of organic phosphate esters (OPEs) under UV irradiation was investigated. In addition, the effects of selected inorganic ions and humic acid (HA) were examined. TCEP, TCPP, and TDCPP hardly undergo degradation via photolysis, and TiO 2 -mediated photocatalysis was confirmed to be effective for removing OPEs present in a water matrix. Inorganic ions (e.g., PO 4 3− , SO 4 2− , Cl − , and NO 3 − ) and HA inhibited the degradation of OPEs. Among these selected ions, PO 4 3− exhibited the strongest inhibition ability, followed by SO 4 2− and then Cl − and NO 3 − , and the inhibition effect increased with the ion concentration. The inhibition effect was caused by two main reasons: (1) Inorganic ions or HA served as ·OH scavengers and competed with OPEs for ·OH. (2) On account of the adsorption of inorganic ions and HA on TiO 2 , the available surface-active sites for OPEs decreased, followed by their oxidation with surface-bound ·OH. The ·OH concentrations were measured by electron spin resonance and the probe method, and it was positively correlated to the degradation rate of OPEs. This study emphasized the importance of inorganic species and HA on the photocatalytic degradation of OPEs and clarified the inhibition mechanism for the degradation of OPEs by the inorganic species or HA. [ABSTRACT FROM AUTHOR]

The effective removal of organics from winery wastewater was obtained in real residual effluents from the wine industry using anodic oxidation (AO). The effluent had an initial organic load of [COD] 0 of 3490 mg L −1 equal to [TOC] 0 of 1320 mg L −1 . In addition, more than 40 organic compounds were identified by means of GC-MS. Different density currents as well as the addition of electrolytes were tested during electrolysis. The results show the decay of [COD] t by 63.6% when no support electrolyte was added, whereas almost total mineralization and disinfection was reached after adding of 50 mM of sodium sulfate and sodium chloride and applying higher density currents. The presence of sulfate and chloride in large concentration favors the production of oxidants such as hydroxyl radicals and active chlorine species that react with organics in solution. Moreover, the addition of a supporting electrolyte to industrial wastewater increases conductivity, reduces cell potential and therefore, decreases the energy consumption of the AO process. [ABSTRACT FROM AUTHOR]

Treatment of composite wastewater generating from the industrial estates is a great challenge. The present study examines the applicability of aerated electrocoagulation and modified peroxi-coagulation processes for removing color and COD from composite wastewater. Iron plates were used as anodes and cathodes in both electrochemical processes and experiments were carried out in a working volume of 2 L. Aeration enhanced the efficiency of electrocoagulation process significantly. More than 50% of COD and 60% of color were removed after 1 h of electrocoagulation process operated at pH 3 and applied voltage of 1 V. Efficiency of the modified peroxi-coagulation process was significantly higher than that of aerated electrocoagulation. COD and color removal efficiencies of the modified peroxi-coagulation process were found as 77.7% and 97%, respectively after 1 h of electrolysis operated at 1 V, solution pH 3 and 50 mM hydrogen peroxide addition. This improved efficiency of modified peroxi-coagulation compared to aerated electrocoagulation is mainly due to the attack of in-situ generated hydroxyl radicals. [ABSTRACT FROM AUTHOR]

Mn-Zn ferrite (Mn 0.6 Zn 0.4 Fe 2 O 4 ) was prepared by a gel method using spent alkaline Zn-Mn batteries as raw materials and employed as catalyst to degrade bisphenol A (BPA) by electro-enhanced heterogeneous activation of peroxydisulfate (PDS). The effects of initial pH, current density, PDS concentration, and Mn-Zn ferrite dosage on BPA removal were investigated. The formation of reactive radicals was verified by electron paramagnetic resonance (EPR) spectroscopy. The results of radical quenching experiments indicate that surface-bound sulfate and hydroxyl radicals played an important role in BPA removal. The stability of Mn 0.6 Zn 0.4 Fe 2 O 4 catalyst was investigated by cycling experiments, which indicates Mn 0.6 Zn 0.4 Fe 2 O 4 is stable and can be reused. This work also provides an alternative way for the reutilization of spent alkaline Zn-Mn batteries. [ABSTRACT FROM AUTHOR]

The effective removal of recalcitrant organochlorine pesticides including hexachlorocyclohexane (HCH) present in a real groundwater coming from a landfill of an old lindane (γ-HCH) factory was performed by electrochemical oxidation using a BDD anode and a carbon felt cathode. Groundwater (ΣHCHs = 0.42 mg L −1 , TOC 0  = 9 mg L −1 , pH 0  = 7, conductivity = 3.7 mS cm −1 ) was treated as received, achieving the complete depletion of the HCH isomers and a mineralization degree of 90% at 4 h electrolysis at constant current of 400 mA. Initial groundwater contains high chloride concentration (Cl 0 −  = 630 mg L −1 ) that is progressively decreased due to its oxidation to different oxychlorine species: Cl 2 , HClO, ClO − , ClO 2 − ClO 3 − and ClO 4 − some of them (Cl 2 , HClO, ClO − ) playing an important role in the oxidation of organic pollutants. The oxidation rate of chloride (and its oxidized intermediates) depends on the applied current value. Although some of the species generated from them are active oxidants, the presence of inorganic salts is detrimental to the efficiency of the electrochemical process when working at current densities above 100 mA due to the high consumption of hydroxyl radicals in wasting reactions. The initial organic carbon content is not crucial for the extension of the process but high organic loads are more profitable for cost effectiveness. The addition of a supporting electrolyte to the solution could be interesting since it increases the conductivity, reducing the cell potential and therefore, decreasing the energy consumption. [ABSTRACT FROM AUTHOR]

Three kinds of graphitic carbon nitride materials (bulk, porous and nanosheet g-C 3 N 4 ) were composited with a multiwall carbon nanotube (MWCNT) by a hydrothermal method, and the obtained b-C 3 N 4 /CNT, p-C 3 N 4 /CNT and n-C 3 N 4 /CNT materials were used in the electrodes for electro-peroxone process. It was found that the n-C 3 N 4 /CNT composite exhibited the highest efficiency in oxalate degradation, though it performed the worst in the oxygen-reduction reaction for H 2 O 2 production. The n-C 3 N 4 /CNT composite exhibited higher activity than CNT and other composites in catalytic ozonation experiments, due to the higher pyrrolic-N content modified on the CNT surface and higher surface area. It also has higher electron transfer ability, which benefited to the electro-reduction of both O 2 and O 3 . The result confirmed that catalytic ozonation process was an important means to enhance the degradation efficiency in the electro-peroxone process, besides peroxone process and O 3 -electrolysis. [ABSTRACT FROM AUTHOR]

Understanding the atmospheric fate of organophosphorus plasticizers is important for their environmental risk assessment. However, limited information is available at present. In this study, density functional theory (DFT) calculations were performed to investigate the transformation mechanism and kinetics of tri-p-cresyl phosphate (TpCP) initiated by OH. Results show that the initial reactions are dominated by H-abstraction and OH addition to form TpCP-radical, TpCP–OH adducts and aryl phosphodiester. The H-abstraction pathways are more favorable than the OH addition pathways. The TpCP-radical and TpCP–OH adducts can further react with O 2 in the atmosphere to finally form benzaldehyde phosphate, hydroxylated TpCP and bicyclic radicals. Based on the transition state theory, the calculated rate constant ( k OH ) of TpCP with OH at T  = 298 K is 1.9 × 10 −12 cm 3 molecule −1 s −1 with an atmospheric lifetime of 4.2 days, which demonstrates that gaseous TpCP is atmospherically persistent. This study provides a comprehensive investigation of the OH-initiated oxidation of TpCP, which is useful for understanding its mechanism of transformation and evaluating the risk in atmospheric environment. [ABSTRACT FROM AUTHOR]

Recent studies have shown the efficiency of hydroxyl radicals generated via ultraviolet (UV)-based advanced oxidation processes (AOPs) combined with hydrogen peroxide (UV/H 2 O 2 ) as a treatment process in water. The effects of AOP treatments on bacterial gene expression was examined using Pseudomonas aeruginosa strain PAO1 as a model-organism bacterium. Many bacterial genes are not expressed all the time, but their expression is regulated. The regulation is at the beginning of the gene, in a genetic region called “promoter” and affects the level of transcription (synthesis of messenger RNA) and translation (synthesis of protein). The level of expression of the regulated genes can change as a function of environmental conditions, and they can be expressed more (induced, upregulated) or less (downregulated). Exposure of strain PAO1 to UV/H 2 O 2 treatment resulted in a major change in gene expression, including elevated expression of several genes. One interesting gene is PA3237, which was significantly upregulated under UV/H 2 O 2 as compared to UV or H 2 O 2 treatments alone. The induction of this gene is probably due to formation of radicals, as it is abolished in the presence of the radical scavenger tert -butanol (TBA) and is seen even when the bacteria are added after the treatment (post-treatment exposure). Upregulation of the PA3237 promoter could also be detected using a reporter gene, suggesting the use of such genetic constructs to develop biosensors for monitoring AOPs in water-treatment plants. Currently biosensors for AOPs do not exist, consequently impairing the ability to monitor these processes on-line according to radical exposure in natural waters. [ABSTRACT FROM AUTHOR]

Biochar(BC)-supported nanoscaled zinc oxide (nZO) was encapsulated either with (nZORc/BC) or with no (nZOR/BC) sodium carboxymethyl cellulose (CMC). The X-ray diffraction and ultraviolet (UV)-visible-near infrared spectrophotometry revealed that nZO of 16, 10, and 20 nm with energy band gaps of 2.79, 3.68 and 2.62 eV were synthesized for nZOR/BC, nZORc/BC and nZO/BC, respectively. The Langmuir isotherm predicted saturated sorption of methylene blue (MB) was 17.01 g kg −1 for nZORc/BC, over 19 times greater than nZOR/BC and nZO/BC. Under UV irradiation, 10.9, 61.6, 83.1, and 41.6% of MB were degraded for nZORc/BC, nZO/BC, nZOR/BC and BC. The scavenging experiment revealed hydroxyl radical dominated CMC degradation. Exogenous CMC (2 g L −1 ) increased MB sorption from 10.6% to 73.1%, but decreased MB degradation from 80.7% to 41.1%, relative to nZOR/BC. Thus, CMC could increase MB sorption by electrostatic attraction and other possible mechanisms. The compromised MB degradation may be ascribed to reduced availability of hydroxyl and superoxide radicals to degrade MB, and increased band gap energy of ZnO. [ABSTRACT FROM AUTHOR]

In the present work advances and limitations in the application of Fe(III)-oxalate complexes (namely, [Fe(Ox) 3 ] 3- ) to the photodegradation of a model persistent organic contaminant - 2,4-dichlorophenoxybutanoic acid (2,4-DB) in neutral aqueous solutions were systematically investigated for the first time. It has been shown that the efficiency of [Fe(Ox) 3 ] 3- system greatly depends on the initial concentrations of oxalate ion due to the fast consumption of the ligand during photodegradation process leading to the formation of photochemically less active Fe(III) species. Efficiency of Fe(Ox) 3 3− system normalized to UVA absorption at the excitation wavelength is practically independent on [Fe(III)]. Thus, it is highly probable that concentrations of Fe(III) as low as < 10 −5  M could be applied in water treatment procedures using reactors with very long optical path. The system also keeps high efficiency at low concentration of pollutant (<10 −5  M) though this results in higher relative consumption rate of Fe(III) and oxalate ions. [ABSTRACT FROM AUTHOR]

Degradation of diethyl phthalate (DEP) by ultraviolet/persulfate (UV/PS) process at different reaction conditions was evaluated. DEP can be degraded effectively via this process. Both tert-butyl (TBA) and methanol (MeOH) inhibited the degradation of DEP with MeOH having a stronger impact than TBA, suggesting sulfate radical ( Image 1 ) and hydroxyl radical (HO ) both existed in the reaction systems studied. The second-order rate constants of DEP reacting with Image 1 and HO were calculated to be ( 6.4 ± 0.3 ) × 10 7 M −1 s −1 and ( 3.7 ± 0.1 ) × 10 9 M −1 s −1 , respectively. To further access the potential degradation mechanism in this system, the pseudo-first-order rate constants (k o ) and the radical contributions were modeled using a simple steady-state kinetic model involving Image 1 and HO . Generally, HO had a greater contribution to DEP degradation than Image 1 . The k o of DEP increased as PS dosages increased when PS dosages were below 1.9 mM. However, it decreased with increasing initial DEP concentrations, which might be due to the radical scavenging effect of DEP. The k o values in acidic conditions were higher than those in alkaline solutions, which was probably caused by the increasing concentration of hydrogen phosphate (with higher scavenging effects than dihydrogen phosphate) from the phosphate buffer as pH values rose. Natural organic matter and bicarbonate dramatically suppressed the degradation of DEP by scavenging Image 1 and HO . Additionally, the presence of chloride ion (Cl − ) promoted the degradation of DEP at low Cl − concentrations (0.25–1 mM). Finally, the proposed degradation pathways were illustrated. [ABSTRACT FROM AUTHOR]

Organophosphorus esters (OPEs) are emerging contaminants widely applied as annexing agents in a variety of industrial products, and they are robust against conventional wastewater treatments. Ultraviolet-driven (UV) radical-based advanced oxidation processes have a potential to become cost-effective treatment technologies for the removal of OPEs in water matrix, but residual and newly generated toxicities of degradation products are a concern. This study is a comprehensive attempt to evaluate UV/H 2 O 2 for the degradation of a water dissolved OPE, tris(2-chloroethyl) phosphate (TCEP). In ultrapure water, a pseudo-first order reaction was observed, and the degradation rate constant reached 0.155 min −1 for 3.5 μM TCEP using 7.0 mW cm −2 UV irradiation with 44.0 μM H 2 O 2 . Hydroxyl radicals were involved in the oxidative degradation of TCEP, as demonstrated by the quenching of the degradation reaction in the presences of tertiary butanol or ethanol. High resolution mass spectroscopy data showed a partial transformation of TCEP to a series of hydroxylated and dechlorinated products e.g., C 4 H 9 Cl 2 O 4 P, C 6 H 13 Cl 2 O 5 P and C 2 H 6 ClO 4 P. Based on proteomics data at molecular and metabolic network levels, the toxicity of TCEP products was reduced obviously as the reaction proceeded, which was confirmed by the up-regulated tricarboxylic acid cycle, fatty acid metabolism and amino acid metabolism in Escherichia coli cells exposed to degradation products mixture. In conclusion, incomplete hydroxylation and dechlorination of TCEP likewise are effective for its detoxification, indicating that UV/H 2 O 2 can be a promising treatment method for OPEs removal. [ABSTRACT FROM AUTHOR]

Flusilazole is an organosilane fungicide used for treatments in agriculture and horticulture for control of diseases. The reaction kinetics and mechanism of flusilazole with sulfate and hydroxyl radicals were studied. The rate constant of the radicals with the fungicide were determined by laser flash photolysis of peroxodisulfate and hydrogen peroxide. The results were 2.0 × 10 9 s −1 M −1 for the reaction of the fungicide with HO and 4.6 × 10 8 s −1 M −1 for the same reaction with SO 4 – radicals. The absorption spectra of organic intermediates detected by laser flash photolysis of S 2 O 8 2− with flusilazole, were identified as α-aminoalkyl and siloxyl radicals and agree very well with those estimated employing the time-dependent density functional theory with explicit account for bulk solvent effects. In the continuous photolysis experiments, performed by photo-Fenton reaction of the fungicide, the main degradation products were: (bis(4-fluorophenyl)-hydroxy-methylsilane) and the non-toxic silicic acid, diethyl bis(trimethylsilyl) ester, in ten and twenty minutes of reaction, respectively. [ABSTRACT FROM AUTHOR]

Electrochemical oxidation (EO) is an advanced oxidation process for water treatment to mineralize organic contaminants. While proven to degrade a range of emerging pollutants in water, less attention has been given to quantify the effect of operational variables such applied current density and pollutant concentration on efficiency and energy requirements. Particular figures of merit were mineralization current efficiency (MCE) and electrical energy per order (E EO ). Linear increases of applied current exponentially decreased the MCE due to the enhancement of undesired parasitic reactions that consumed generated hydroxyl radical. E EO values ranged from 39.3 to 331.8 kW h m −3 order −1 . Increasing the applied current also enhanced the E EO due to the transition from kinetics limited by current to kinetics limited by mass transfer. Further increases in current did not influence the removal rate, but it raised the E EO requirement. The E EO requirement diminished when decreasing initial pollutant loading with the increase of the apparent kinetic rate because of the relative availability of oxidant per pollutant molecule in solution at a defined current. Oxidation by-products released were identified, and a plausible degradative pathway has been suggested. [ABSTRACT FROM AUTHOR]

Odorous volatile organic compounds (VOCs) deteriorate the quality of life and affect human health. In this study, a process was developed to remove an odorous VOC using a combined non-thermal plasma (NTP) and wet scrubber (WS) system. The low removal efficiency of WSs and the large amount of ozone generated by NTP were resolved. Compared to the decomposition effects when using a WS and NTP separately, the NTP + WS system improved the removal efficiency of ethyl acrylate (EA) and significantly reduced ozone emissions. The maximum EA removal efficiency was 99.9%. Additionally, an EA removal efficiency of over 53.4% and a 100% ozone removal efficiency were achieved even at discharge voltages lower than 4.5 kV. Ozone catalysis was confirmed to occur in the NTP + WS system. Furthermore, we verified the removal of by-products such as residual ozone and formaldehyde, which is a representative organic intermediate of EA. This study demonstrates that the NTP + WS system is a green technology for removing odorous VOCs. [Display omitted] • The combined NTP + WS system for removing odorous VOC is proposed. • The VOC removal efficiency is considerably increased. • Secondary air pollution associated with ozone and organic intermediate is reduced. • The VOC degradation mechanism in the NTP + WS system was explored. [ABSTRACT FROM AUTHOR]

Carbon-based sandwich-like electrocatalyst with a hierarchical structure, carbon sheet (CS)-loaded Ce-doped SnO 2 nanoparticles, were successfully prepared using a simple method, which presented a high-efficiency electrocatalytic performance for tetracycline decomposition. Among them, Sn 0.75 Ce 0.25 O y /CS exhibits superior catalytic activity, such as more than 95% of tetracycline was removed (120 min), and over 90% of total organic carbon was mineralized (480 min). It is found from morphology observation and computational fluid dynamics simulation that the layered structure is conducive to improving the mass transfer efficiency. Through X-Ray powder diffraction, X-ray photoelectron spectroscopy, Raman spectrum, and density functional theory calculation analyze that the structural defect in Sn 0.75 Ce 0.25 O y caused by Ce doping is considered to play the key role. Moreover, electrochemical measurements and degradation experiments further prove that the outstanding catalytic performance is attributable to the initiated synergistic effect established between CS and Sn 0.75 Ce 0.25 O y. These results explain the effectiveness of Sn 0.75 Ce 0.25 O y /CS for the remediation of tetracycline-contaminated water and mitigating the potential risks and imply that the Sn 0.75 Ce 0.25 O y /CS composite has a deeply practical value in tetracycline wastewater degradation and a promise for further application. [Display omitted] • Higher degradation performance caused by more lattice defect in Sn x Ce 1-x O y catalyst. • "Sandwich" structure boosts mass transfer efficiency on catalyst surface. • Porous carbon endows Sn 0.75 Ce 0.25 O y with a bigger electrochemcial index. • An overpotential higher than standard SnO 2 is obtained by the doping of Ce into SnO 2. • Catalyst activity is reasonably explained by CFD and DFT theoretical research tolls. [ABSTRACT FROM AUTHOR]

Recalcitrant and toxic organic pollutants from wastewaters are scarcely removed in conventional wastewater treatment plants. To preserve the water quality, organics need to be removed by developing powerful oxidation technologies. Our laboratory proposed in 2007 a potent electrochemical advanced oxidation process (EAOP) for wastewater remediation, so-called solar photoelectro-Fenton (SPEF). This review summarizes the advances of this emerging technology up to 2022, making evident its effectiveness and cost-efficiency for the destruction of usual organic pollutants. The simultaneous action of generated hydroxyl radicals and the photolysis by sunlight explains the high oxidation power of SPEF respect to other EAOPs. The review is initiated by describing the fundamentals of the process to remark the role of the produced oxidants and the benefits of using solar irradiation in its performance. The photoelectrochemical systems used (bench tank reactor and solar pre-pilot flow plant) and the assessment of the operating variables are discussed. The characteristics of the most common homogeneous SPEF for the degradation and mineralization of several synthetic solutions of industrial chemicals, herbicides, pharmaceuticals, and synthetic organic dyes, as well as of some real wastewaters, are further described. The influence of the photoelectrochemical cell, electrodes, solution pH, electrolyte composition, Fe2+ and pollutant concentration, and current density is analyzed. The performance of a homogeneous SPEF-like process with active chlorine and heterogeneous SPEF processes with solid catalysts such as Fe 3 O 4 and sodium vermiculite is also discussed. Finally, the advances of homogeneous SPEF combined with other techniques like solar photocatalysis, solar photoelectrocatalysis, anaerobic digestion, and nanofiltration are reported. [Display omitted] • Advances in solar photoelectro-Fenton (SPEF) process in the period 2007–2022 are summarized. • Similar degradation of organic pollutants with homo-EF, homo-PEF, and homo-SPEF at pH 3.0 • Larger mineralization by homo-SPEF than homo-PEF: more potent UV intensity from sunlight. • Good performance of hetero-SPEF with Fe 3 O 4 or sodium vermiculite as hetero-catalyst at pH 3.0 • Combined processes with solar photoelectrocatalysis, anaerobic digestion, and nanofiltration. [ABSTRACT FROM AUTHOR]

A novel and recyclable composite material, Fe 3 O 4 /N co-doped sludge biochar (FNBC), was developed from original sludge biochar (BC) and found to have excellent stability and superior catalytic capacity during the ciprofloxacin (CIP) degradation under the action of peroxymonosulfate (PMS). In the FNBC/PMS system, an approximately complete removal of CIP was achieved within 60 min under the condition of 1.0 g/L FNBC, 3.0 mM PMS, and 20 mg/L CIP, which was about 2.08 times of that in BC/PMS system (48.01%). Besides, FNBC/PMS system could effectively remove CIP under the influence of wide pH (2.0–10.0) or inorganic ions compared with BC/PMS system. Moreover, it was found that there were radical produced under the effect of Fe element, defects, functional groups, pyridinic N and pyrrolic N and non-radical caused by graphitic N, carbon atoms next to the iron atoms and better adsorption capacity in the FNBC/PMS system. It was observed that the contribution of hydroxyl radical (•OH), sulfate radical (SO 4 •−) and singlet oxygen (1O 2), which were the main reactive oxygen species, during the CIP degradation, were 75.80%, 11.49% and 10.26%, respectively. Furthermore, total organic carbon (TOC) variation was analyzed and the degradation pathway of CIP was speculated. The application of this material could combine the recycling of sludge with the effective degradation of refractory organic pollutant, providing an environmentally friendly and economic method. [Display omitted] • Fe 3 O 4 /N co-doped sludge biochar (FNBC) showed 2.08-fold higher activity to biochar. • FNBC/PMS system has radical and non-radical pathways to oxidize CIP. • •OH played a primary role in the CIP degradation in FNBC/PMS system. • The degradation pathway of CIP was speculated. • FNBC had excellent stability and recyclability. [ABSTRACT FROM AUTHOR]