Sustainable Generation of Sulfate Radicals and Decontamination of Micropollutants via Sequential Electrochemistry

The removal of emerging micropollutants in the aquatic environment remains a global challenge.Conventional routes are often chemically,energetically,and operationally intensive,which decreases their sustainability during applications.Herein,we develop an advanced chemical-free strategy for micropollutants decontamination that is solely based on sequential electrochemistry involving ubiquitous sulfate anions in natural and engineered waters.This can be achieved via a chain reaction initiated by electrocatalytic anodic sulfate(SO_(4)^(2-))oxidation to produce persulfate(S_(2)O_(8)^(2-))and followed by a cathodic persulfate reduction to produce sulfate radicals(SO_(4)^(·-)).These SO_(4)^(·-)are powerful reactive species that enable the unselective degradation of micropollutants and yield SO_(4)^(2-)again in the treated water.The proposed flow-through electrochemical system achieves the efficient degradation(100.0%)and total organic carbon removal(65.0%)of aniline under optimized conditions with a single-pass mode.We also reveal the effectiveness of the proposed system for the degradation of a wide array of emerging micropollutants over a broad pH range and in complex matrices.This work provides the first proof-ofconcept demonstration using ubiquitous sulfate for micropollutants decontamination,making water purification more sustainable and more economical.

Bacteria inactivation by sulfate radical:progress and non-negligible disinfection by-products

Sulfate radicals have been increasingly used for the pathogen inactivation due to their strong redox ability and high selectivity for electron-rich species in the last decade.The application of sulfate radicals in water disinfection has become a very promising technology.However,there is currently a lack of reviews of sulfate radicals inactivated pathogenic microorganisms.At the same time,less attention has been paid to disinfection by-products produced by the use of sulfate radicals to inactivate microorganisms.This paper begins with a brief overview of sulfate radicals’properties.Then,the progress in water disinfection by sulfate radicals is summarized.The mechanism and inactivation kinetics of inactivating microorganisms are briefly described.After that,the disinfection by-products produced by reactions of sulfate radicals with chlorine,bromine,iodide ions and organic halogens in water are also discussed.In response to these possible challenges,this article concludes with some specific solutions and future research directions.

Oxygen dependent oxidation of trimethoprim by sulfate radical:Kinetic and mechanistic investigations

Trimethoprim(TMP)is a typical antibiotic to treat infectious disease,which is among the most commonly detected antibacterial agents in natural waters and municipal wastewaters.In the present study,the impacts of dissolved oxygen(DO)on the oxidation efficiency and pathways of TMP by reaction with sulfate radicals(SO_(4)^(-1))were investigated.Our results revealed that the presence of DO was favourable for TMP degradation.Specifically,TMP would react initially with SO_(4)^(-1)via electron-transfer process to form a carbon-centered radical.In the absence of oxygen,the carbon-centered radical could undergo hydrolysis to produceα-hydroxytrimethoprim(TMPàOH),followed by the further oxidation which generatedα-ketotrimethoprim(TMP=O).However,in the presence of oxygen,the carbon-centered radical would alternatively combine with oxygen,leading to a sequential reaction in which peroxyl radical and a tetroxide were formed,and finally generated TMPàOH and TMP=O simultaneously.The proposed pathways were further confirmed by density functional theory(DFT)calculations.The results obtained in this study would emphasize the significance of DO on the oxidation of organic micropollutants by SO_(4)^(-1).

Stable and efficient metal-biochar supported catalyst:degradation of model pollutants through sulfate radical-based advanced oxidation processes

This study focuses on the synthesis of metal-based biochar catalysts and their catalytic activation of peroxymonosulfate(PMS,HSO5−)for the degradation of three different wastewater model pollutants employing advanced oxidation processes(AOP).Iron,copper,and two different cobalt-based catalysts were prepared and evaluated.The catalysts were supported on a biochar obtained from the pyrolysis of woody pruning wastes.They were characterized by C,H,and N elemental analysis,X-Ray diffraction(XRD),Fourier-transform infrared spectroscopy(FTIR),and scanning electron microscope(SEM).The metal content in each catalyst was determined by means of atomic absorption spectroscopy(AAS).The degradation reac-tions of benzoic acid(BA),catechol(C),and cinnamic acid(CA)were carried out in a lab scale batch glass reactor and were followed by UV-Visible spectroscopy(UV-Vis).A colorimetric technique was employed to verify the presence of oxidant during the reaction progress.The catalyst/oxidant optimal ratio was determined for the cobalt catalysts.The mineralization degree of the pollutants after the degradations was verified by means of total organic carbon(TOC)content in the residual liquids.After 4 h of reaction,the maximum mineralization was reached when C was treated with a cobalt-based catalyst(>80%),and its stability was evaluated through successive cycles of use.

A novel advanced oxidation process to degrade organic pollutants in wastewater:Microwave-activated persulfate oxidation

This article, for the first time, provides a novel advanced oxidation process based on sulfate radical （SO^4·-） to degrade organic pollutants in wastewater： microwave （MW）-activated persulfate oxidation （APO） with or without active carbon （AC）. Azo dye acid Orange 7 （AO7） is used as a model compound to investigate the high reactivity of MW-APO. It is found that AO7 （up to 1000 mg/L） is completely decolorized within 5-7 min under an 800 W MW furnace assisted-APO. In the presence of chloride ion （up to 0.50 mol/L）, the decolorization is still 100% completed, though delayed for about 1-2 min. Experiments are made to examine the enhancement by AC. It is exciting to find that the 100% decolorization of AO7 （500 mg/L） is achieved within 3 min by MW-APO using 1.0 g/L AC as catalyst, while the degradation efficiency maintains at 50% by MW energy without persulfate after about 5 min. Besides the destruction of visible light chromophore band of AO7 （484 nm）, during MW-APO, two bands in the ultraviolet region （228 nm and 310 nm） are rapidly broken down. The removal of COD is about 83%-95% for 500 mg/L AO7. SO^4·- is identified with quenching studies using specific alcohols. Both SO^4·- and ·OH could degrade AO7, but SO^4·- plays the dominant role. In a word, MW-APO AC is a new catalytic combustion technology for destruction of organic contamination even for high concentration.

A granular adsorbent-supported Fe/Ni nanoparticles activating persulfate system for simultaneous adsorption and degradation of ciprofloxacin

In this work,Fe/Ni nanoparticles were produced through Fe(II)and Ni(II)reduction by NaBH4 and they were stabilized by a kind of prepared granular adsorbent(Fe/Ni@PGA).Fe/Ni@PGA as an environment-friendly activator was used to activate persulfate(PS)for the removal of ciprofloxacin from aqueous solution.Fe/Ni@PGA was systematically characterized via Brunauer-Emmett-Teller(BET)method,X-ray diffraction(XRD),scanning electron microscopy(SEM),and Fourier transform infrared spectroscopy(FTIR).The effects of PS concentration,initial solution pH,Fe/Ni@PGA dosage,initial ciprofloxacin concentration,reaction temperature,anions,and natural organic matters on the removal of ciprofloxacin by Fe/Ni@PGA/PS were analyzed.The removal efficiency of ciprofloxacin by Fe/Ni@PGA/PS was 93.24%under an initial pH of 3.0,PS concentration of 10 mM,Fe/Ni@PGA dosage of 0.1 g,and reaction temperature of 30℃.Fe/Ni@PGA could still exhibit high catalytic activity after nine cycles of regeneration.The removal mechanisms for ciprofloxacin by the Fe/Ni@PGA/PS system were proposed.In summary,the Fe/Ni@PGA/PS system could be applied as a promising technology for ciprofloxacin removal.

Reactions between the SO^(·-)_4 radical and some common anions in atmospheric aqueous droplets

The rate constants of reactions between the SO4^- radical and some common anions in atmospheric aqueous droplets e.g. Cl^-,NO^-, HSO3^- and HCO3^- were determined using the laser flash photolysis technique.Absorption spectra of SO4^- and the product radicals were also reported.The chloride ion was evaluated among all the anions to be the most efficient scavenger of SO4^-.The results may supply useful information for a better understanding of the vigorous radical-initiated reactions in atmospheric aqueous droplets such as clouds, rains or fogs.

Activation of peroxydisulfate by gas-liquid pulsed discharge plasma to enhance the degradation of p-nitrophenol

Pulsed discharge in water and over water surfaces generates ultraviolet radiation,local high temperature,shock waves,and chemical reactive species,including hydroxyl radicals,hydrogen peroxide,and ozone.Pulsed discharge plasma（PDP） can oxidize and mineralize pollutants very efficiently,but high energy consumption restricts its application for industrial wastewater treatment.A novel method for improving the energy efficiency of wastewater treatment by PDP was proposed,in which peroxydisulfate（PDS） was added to wastewater and PDS was activated by PDP to produce more strong oxidizing radicals,including sulfate radicals and hydroxyl radicals,leading to a higher oxidation capacity for the PDP system.The experimental results show that the increase in solution conductivity slightly decreased the discharge power of the pulse discharge over the water surface.An increase in the discharge intensity improved the activation of PDS and therefore the degradation efficiency and energy efficiency of p-nitrophenol（PNP）.An increase in the addition dosage of PDS greatly facilitated the degradation of PNP at a molar ratio of PDS to PNP of lower than 80：1,but the performance enhancement was no longer obvious at a dosage of more than 80：1.Under an applied voltage of 20 kV and a gas discharge gap of 2 mm,the degradation efficiency and energy efficiency of the PNP reached 90.7%and45.0 mg kWh^（-1） for the plasma/PDS system,respectively,which was 34%and 18.0 mg kWh^（-1）higher than for the discharge plasma treatment alone.Analysis of the physical and chemical effects indicated that ozone and hydrogen peroxide were important for PNP degradation and UV irradiation and heat from the discharge plasma might be the main physical effects for the activation of PDS.

Degradation of bisphenol A using electrochemical assistant Fe(II)-activated peroxydisulfate process

Degradation of bisphenol A（BPA） in aqueous solution using sulfate radicals was investigated using the Fe（II）-activated peroxydisulfate（PDS） process, electrochemical process, electrochemical process with 2.5 mmol/L Na2S2O8 without Fe（II）, and electrochemical assistant Fe（II）-activated PDS process. It was found that the electrochemical assistant Fe（II）-activated PDS process performed best in the degradation of BPA.The variables considered to influence the degradation efficiency of BPA were the initial concentration of Fe2 t, the initial concentration of Na2S2O8, and the current density. More than 97% of the BPA removals were achieved within 120 min under the optimum operational condition.The degradation of BPA was accompanied by the formation of phenol, hydroquinone, and small-molecule compounds such as succinic acid. The electron transfer was the principal step in the oxidation of BPA.

Cobalt doping amount determines dominant reactive species in peroxymonosulfate activation via porous carbon catalysts co-doped by cobalt and nitrogen

Switching the reaction routes in peroxymonosulfate(PMS)-based advanced oxidation processes have attracted much attention but remain challenging.Herein,a series of Co-N/C catalysts with different compositions and structures were prepared by using bimetallic zeolitic imidazolate frameworks based on ZIF-8 and ZIF-67(x Zn/Co-ZIFs).Results show that Co doping amount could mediate the transformation of the activation pathway of PMS over CoN/C.When Co doping amount was less than 10%,the constructed x Co-N/C/PMS system(x≤10%)was singlet oxygen-dominated reaction;however further increasing Co doping amount would lead to the generation and coexistence of sulfate radicals and high-valent cobalt,besides singlet oxygen.Furthermore,the nitrogen-coordinated Co(Co-NX)sites could serve as main catalytically active sites to generate singlet oxygen.While excess Co doping amount caused the formation of Co nanoparticles from which leached Co ions were responsible for the generation of sulfate radicals and high-valent cobalt.Compared to undoped N/C,Co doping could significantly enhance the catalytic performance.The 0.5%Co-N/C could achieve the optimum degradation(0.488 min^(-1))and mineralization abilities(78.4%)of sulfamethoxazole among the investigated Co-N/C catalysts,which was superior to most of previously reported catalysts.In addition,the application prospects of the two systems in different environmental scenarios(pH,inorganic anions and natural organic matter)were assessed and showed different degradation behaviors.This study provides a strategy to regulate the reactive species in PMS-based advanced oxidation process.

Location and size regulation of manganese oxides within mesoporous silica for enhanced antibiotic degradation

Refractory antibiotics in domestic wastewater are hard to be completely eliminated by conventional methods,and then lead to severe environmental contamination and adverse effects on public health.In present work,advanced oxidation processes(AOPs)are adopted to remove the antibiotic of sul-fachloropyridazine(SCP).Nanosized Mn_(2)O_(3) was fabricated on the SBA-15 material to catalytically acti-vate potassium peroxydisulfate(PDS)to generate reactive oxygen radicals of.OH and SO_(4).for SCP degradation.The effects of location and size of Mn_(2)O_(3) were explored through choosing either the as-made or template free SBA-15 as the precursor of substrate.Great influences from the site and size of Mn_(2)O_(3) on the oxidation activity were discovered.It was found that Mn_(2)O_(3) with a large size at the exterior of SBA-15(Mn-tfSBA)was slightly easier to degrade SCP at a low manganese loading of 1.0-2.0 mmol.g;however,complete SCP removal could only be achieved on the catalyst of Mn_(2)O_(3) with a refined size at the interior of SBA-15(Mn-asSBA).Moreover,the SO_(4).species were revealed to be the decisive radicals in the SCP degradation processes.Exploring the as-made mesoporous silica as a support provides a new idea for the further development of environmentally friendly catalysts.

Study on the Methods for Removing Sulfide Ion and Sulfate Radical from the Oilfield Sewage

Sulfide ion can reduce the viscosity of polymer solution. The higher the concentration of sulfide ion is, the greater the effect of viscosity on polymer is, and it directly affects oil recovery rate. Some methods for removing sulfide were studied by adding the oxidizing substances. Each method had certain effect on removing sulfide. The addition of hydrogenperoxide in the solution makes it faster to remove sulfide than flowing air in it, although the removal of sulfide is still not complete. This removal is quick when ozone takes part in, and it will spend much time with the increased volume of solution. The extent of removing sulfide was mainly related to the oxidability of re- moved substances. The stronger the oxidability of oxidizing substances was, the better the performance for sulfide removing was. In addition, part of sulfate radical in oilfield sewage could be removed by nanofiltration membrane. Removal efficiency of sulfate radical is about 50%. The probability may be avoided that sulfate radical was reduced into sulfide by the sulfate-reducing bacteria （SRB） in sewage. This method could radically reduce the presence of the reduction of sulfur in sewage, and it can reduce the corrosion of underground oil pipeline.

Removal of nitric oxide from simulated flue gas using aqueous persulfate with activation of ferrous ethylenediaminetetraacetate in the rotating packed bed

Nitric oxide being a major gas pollutant has attracted much attention and various technologies have been developed to reduce NO emission to preserve the environment.Advanced persulfate oxidation technology is a workable and effective choice for wet flue gas denitrification due to its high efficiency and green advantages.However,NO absorption rate is limited and affected by mass transfer limitation of NO and aqueous persulfate in traditional reactors.In this study,a rotating packed bed(RPB)was employed as a gas-liquid absorption device to elevate the NO removal efficiency(η_(NO))by aqueous persulfate((NH_(4))_(2)S_(2)O_(8))activated by ferrous ethylenediaminetetraacetate(Fe^(^(2+))-EDTA).The experimental results regarding the NO absorption were obtained by investigating the effect of various operating parameters on the removal efficiency of NO in RPB.Increasing the concentration of(NH_(4))_(2)S_(2)O_(8) and liquid-gas ratio could promoted the oxidation and absorption of NO while theη_(NO) decreased with the increase of the gas flow and NO concentration.In addition,improving the high gravity factor increased theη_(NO) and the total volumetric mass transfer coefficient(K_(G)α )which raise theη_(NO) up to more than 75%under the investigated system.These observations proved that the RPB can enhance the gas-liquid mass transfer process in NO absorption.The correlation formula between K_(G)α and the influencing factors was determined by regression calculation,which is used to guide the industrial scale-up application of the system in NO removal.The presence of O_(2) also had a negative effect on the NO removal process and through electron spin resonance spectrometer detection and product analysis,it was revealed that Fe^(2+)-EDTA activated(NH_(4))2S_(2)O_(8) to produce•SO_(4)^(-),•OH and•O_(2)^(-),played a leading role in the oxidation of NO,to produce NO_(3)^(-)as the final product.The obtained results demonstrated a good applicable potential of RPB/PS/Fe^(2+)-EDTA in the removal of NO from flue gases.

A data-based review on norfloxacin degradation by persulfate-based advanced oxidation processes:Systematic evaluation and mechanisms

Persulfate-based advanced oxidation processes(AOPs)have obtained increasing attention due to the generation of sulfate radical(SO_(4)-)with high reactivity for organic contaminants degradation,Numerous activation methods have been used to activate two common persulfates:peroxymonosulfate(PMS)and peroxydisulfate(PDS).However,the comparisons of activation methods and two oxidants in the comprehensive degradation performance of the target contaminant are still limited.Thus,taking norfloxacin(NOR)as the target contaminant,we proposed five key parameters(the observed pseudo-first-order rate constant,kobs;average mineralization rate,rm;utilization efficiency of catalyst,Ucat;utilization efficiency of oxidant,Uox;and net utilization efficiency of oxidant,Uox')to quantify the comprehensive degradation performance of NOR.The irradiation affected target pollutants,catalysts,and oxidants,leading to an improved degradation performance of NOR.Various heterogeneous catalysts were compared in terms of the key elements contained.Fe,Co,and Mn-based materials performed better,while carbon-based catalysts performed poorly on NOR degradation.The overall degradation performance of NOR was different for PMS and PDS,which can be ascribed to their varied reaction pathways towards NOR,but stemmed from different properties of PMS and PDS.Besides,the effect of pH on the degradation efficiency of NOR was investigated.A neutral solution was optimal for PMS system,while an acidic solution worked better for PDS system.Finally,we analyzed the molecule structure of NOR by density functional theory(DFT)calculation to study the sites easy to attack.Then,we summarized four typical degradation pathways of NOR in SO_(4)^(-)-based AOP systems,including defluorination,piperazine ring cleavage,piperazine ring oxidation,and quinoline group transformation.

Reactive species regulation by interlayered Na^(+)/H^(+)of titanate nanotubes decorated Co(OH)_(2)hollow microsphere for peroxymonosulfate activation and gatifloxacin degradation

Emerging organic pollutants(EoPs)in water are of great concern due to their high environmental risk,so urgent technologies are needed for effective removal of those pollutants.Herein,a heterogeneous advanced oxidation process(AoP)of peroxymonosulfate(PMS)activation by functional material was developed for degradation of a typical antibiotic,gatifloxacin(GAT).The reactive species including sulfate radical(SO^(4)^(·-))and singlet oxygen(^(1)O_(2))in this AOP were regulated by interlayered ions(Na^(+)/H^(+))of titanate nanotubes that supported on Co(OH)_(2)hollow microsphere.Both the Na-type(NaTi-CoHS)and H-type(HTi-CoHS)materials achieved efficient PMS activation for GAT degradation,and HTi-CoHS even exhibited a relatively high degradation efficiency of 96.6%within 5 min.Co(OH)_(2)was considered the key component for generation of SO_(4)^(·-)after PMS activation,while hydrogen titanate nanotubes(H-TNTs)promoted the transformation of peroxysulfate radical(SO_(5)^(·-))to ^(1)O_(2) by hydrogen bond interaction.Therefore,when the interlayer ion of TNTs transformed from Na^(+) to H^(+),more ^(1)O_(2) was produced for organic pollutant degradation.H-TNTs with lower symmetry preferred to adsorb PMS molecules to achieve interlayer electron transport through hydrogen bonding,rather than electrostatic interaction of Na^(+) for Na-TNTs.In addition,the degradation pathway of GAT mainly proceeded by the cleavage of C-N bond at the 8 N site of the piperazine ring,which was confirmed by condensed Fukui index and mass spectrographic analysis.This work gives new sights into the regulation of reactive species in AoPs by the composition of material and promotes the understanding of pollutant degradation mechanisms in water treatment process.

Enhanced persulfate activation process by magnetically separable catalysts for water purification:A review

In recent years,persulfate(PS)-based advanced oxidation processes(AOPs)have become a hot research topic for degrading environmental pollutants due to their excellent oxidation capacity,selectivity,and stability.PS-AOPs can generate sulfate radicals(SO^(·-)_(4))with strong oxidation ability,but single PS produces limited or no radicals.Therefore,activation of PS by energy input or catalyst dosing is used to improve its oxidation performance.However,the addition of disposable catalyst not only causes a waste of resources,but also may lead to secondary pollution.Therefore,magnetically separable catalysts for activating PS have received widespread attention due to their reusability.Although there are few literature reviews on the activation of PS by carbon-or iron-based magnetic materials,the mechanism analysis of the activation of PS by magnetic materials to degrade pollut-ants is not deep enough,and the discussion of material types is not comprehensive and detailed.Moreover,the discussion of magnetic materials in terms of recycling properties is lacking.Therefore,this review firstly sum-marizes and analyzes the mechanism of magnetically separable catalysts activating PS to degrade pollutants.Then,the research progress of zero-valent iron(ZVI,Fe^(0))-based,iron oxide-based,bimetallic oxide-based,and other magnetically separable catalyst is introduced,and the tailoring engineering approaches and reusability of magnetically separable catalysts are discussed.Finally,some possible material optimization suggestions are proposed in this paper.In conclusion,this review is expected to provide useful insights for improving the per-formance and reusability of magnetically separable materials activated PS in the future.

Degradation of iopamidol in the permanganate/sulfite process:Evolution of iodine species and effect on the subsequent formation of disinfection by-products

Permanganate/sulfite(Mn(VII)/S(IV))process is a promising pre-oxidation technology for sequestering the emerging organic contaminants in drinking water treatment plant.Iopamidol(IPM),a representative of iodinated X-ray contrast media,has been widely detected in water sources and has the risk of forming iodinated disinfection byproducts(I-DBPs)in water treatment system.In this study,we investigated the evolution of iodine species during the IPM degradation by the Mn(VII)/S(IV)process and its effect on the subsequent formation of I-DBPs during chlorination at pH 7.0 and 8.0.IPM could be effectively degraded in the Mn(VII)/S(IV)process at environmentally relevant pH(pH 7.0 and 8.0).The results of quenching and competitive oxidation kinetic experiments revealed that SO^(·-)_(4)was the major reactive oxidizing species contributing to the degradation of IPM whereas the contributions of HO·and reactive manganese species were negligible in the Mn(VII)/S(IV)process.I–and IO–3were generated while no HOI was detected during the degradation of IPM in the Mn(VII)/S(IV)process.The effects of IPM oxidation by Mn(VII)/S(IV)on the subsequent formation of chlorinated disinfection by-products(Cl-DBPs)during chlorination were related to the category of Cl-DBPs.The pre-oxidation of IPM by Mn(VII)/S(IV)resulted in the generation of I-DBPs during the disinfection process although no I-DBPs were detected if no pre-oxidation was applied.The finding of this study suggested that attention should be paid to the toxicity of DBPs when water containing iodinated organic contaminants is treated by Mn(VII)/S(IV)process or other pre-oxidation technologies.

Recent advances in persulfate-based advanced oxidation processes for organic wastewater treatment

In recent years,with the emergence of new pollutants,the effective treatment of wastewater has become very important.Persulfate-based advanced oxidation processes have been successfully applied to the treatment of wastewater,such as wastewater containing antibiotics,pharmaceuticals and personal care products,dyes,endocrine-disrupting chemicals,chlorinated organic pollutants,and phenolics,for the degradation of refractory organic contaminants.This paper summarizes the production of sulfate radicals,which can be generated by the activation of persulfate via conventional and emerging approaches.The existing problems of persulfate-based advanced oxidation processes were analyzed in detail,including residual sulfates,coexisting factors(coexisting inorganic anions and natural organic matter),and energy consumption.This paper proposes corresponding possible solutions to the problems mentioned above,and this paper could provide a reference for the application of persulfate-based advanced oxidation processes in actual wastewater treatment.

CuFe2O4@GO nanocomposite as an effective and recoverable catalyst of peroxymonosulfate activation for degradation of aqueous dye pollutants

Recently,heterogeneous activation of peroxymonosulfate(PMS) to oxidatively degrade organic pollutants has been a hotspot.In the present work,copper ferrite-graphite oxide hybrid(CuFe2 O4@GO)was prepared and used as catalyst to activate PMS for degradation of methylene blue(MB) in aqueous solution.A high degradation efficiency(93.3%) was achieved at the experimental conditions of20 mg/L MB,200 mg/L CuFe2 O4@GO,0.8 mmol/L PMS,and 25℃temperature.Moreover,CuFe2 O4@GO showed an excellent reusability and stability.The effects of various operational parameters including pollutant type,solution pH,catalyst dosage,PMS dosage,pollutant concentration,temperature,natural organic matter(NOM),and inorganic anions on the catalytic degradation process were comprehensively investigated and elucidated.The further mechanistic study revealed the Cu(Ⅱ)/Cu(Ⅰ) redox couple on CuFe2 O4@GO played the dominant role in PMS activation,where both hydroxyl and sulfate radicals were generated and proceeded the degradation of pollutants.In general,CuFe2 O4@GO is a promising heterocatalyst for PMS-based advanced oxidation processes(AOPs) in wastewater treatment.

Diatomite supported nano zero valent iron with 3D network for peroxymonosulfate activation in efficient degradation of bisphenol A

Diatomite supported nano zero valent iron(n ZVI)catalyst(NDA)with complex network structure was prepared via a mild reduction precipitation method in this work.The pore structure and pore distribution of NDA can be regulated and controlled through adjusting the loading amount of n ZVI.In general,the nano three-dimensional network formed by n ZVI and diatomite channels greatly increase the specific surface area and pore volume of NDA,and further formed more active sites,which made NDA have better performance in activating PMS to degrade BPA than pure n ZVI.The pseudo-first-order reaction rate constant of 50-NDA(50%-n ZVI/diatomite)is almost 3 times higher than that of pure n ZVI.Besides,the electron paramagnetic resonance(EPR)and radical quenching experiments showed that the activation process was dominated by the sulfate radical(SO_(4)^(-))and hydroxyl radical(·OH)produced by Fe;oxidation.The generated electrons promote the self-decomposition of PMS to produce singlet oxygen(^(1)O_(2)),and then the valence state of iron changes to produce free radicals.In addition,the possible degradation pathway of BPA was inferred from the intermediate products identified by liquid chromatograph-mass spectrometer(LC-MS).This study provides a novel strategy for the design and preparation of three-dimensional composite catalysts derived from natural mineral.