This study explored the catalytic mechanism and performance impacted by the materials ratio of Fe_(3)O_(4)-GO_(x) composites in three typical advanced oxidation processes(AOPs)of O_(3),peroxodisulfate(PDS)and photo-Fe...This study explored the catalytic mechanism and performance impacted by the materials ratio of Fe_(3)O_(4)-GO_(x) composites in three typical advanced oxidation processes(AOPs)of O_(3),peroxodisulfate(PDS)and photo-Fenton processes for tetracycline hydrochloride(TCH)degradation.The ratio of GO in the Fe_(3)O_(4)-GO_(x) composites exhibited different trends of degradation capacity in each AOPs based on different mechanisms.Fe_(3)O_(4)-rGO_(20wt%) exhibited the optimum catalytic performance which enhanced the ozone decomposition efficiency from 33.48%(ozone alone)to 51.83%with the major reactive oxygen species(ROS)of O_(2)·-.In PDS and photo-Fenton processes,Fe_(3)O_(4)-rGO_(5wt%) had the highest catalytic performance in PDS and H_(2)O_(2) decomposition for SO_(4)·–,and·OH generation,respectively.Compared with using PDS alone,PDS decomposition rate and TCH degradation rate could be increased by 5.97 and 1.73 times under Fe_(3)O_(4)-rGO_(5wt%) catalysis.In the photo-Fenton system,Fe_(3)O_(4)-rGO_(5wt%) with the best catalyst performance in H_(2)O_(2) decomposition,and TCH degradation rate increased by 2.02 times compared with blank group.Meantime,the catalytic mechanisms in those systems of that the ROS produced by conversion between Fe^(2+)/Fe^(3+)were also analyzed.展开更多
Pd modified electrodes possess problems such as easy agglomeration and low electrolytic ability,and the use of manganese dioxide(MnO_(2)) to facilitate Pd reduction of organic pollutants is just started.However,there ...Pd modified electrodes possess problems such as easy agglomeration and low electrolytic ability,and the use of manganese dioxide(MnO_(2)) to facilitate Pd reduction of organic pollutants is just started.However,there is still a limited understanding of how to match the Pd load and MnO_(2) to realize optimal dechlorination efficiency at minimum cost.Here,a Pd/MnO_(2)/Ni foam cathode was successfully fabricated and applied for the efficient electrochemical dechlorination of 2,4,6-trichlorophenol(2,4,6-TCP).The optimal electrocatalytic hydrodechlorination(ECH)performance with 2,4,6-TCP dechlorination efficiency(92.58%in 180 min)was obtained when the concentration of PdCl_(2) precipitation was 1 mmol/L,the deposition time of MnO_(2) was 300 s and cathode potential was-0.8 V.Performance influenced by the exogenous factors(e.g.,initial pH and coexisted ions)were further investigated.It was found that the neutral pH was the most favorable for ECH and a reduction in dechlorination efficiency(6%~47.6%)was observed in presence of 5 mmol/L of NO_(2)^(-),NO_(3)^(-),S^(2-)or SO_(3)^(2-).Cyclic voltammetry(CV)and quenching experiments verified the existence of three hydrogen species on Pd surface,including adsorbed atomic hydrogen(H^(*)_(ads)),absorbed atomic hydrogen(H^(*)_(abs)),and molecular hydrogen(H_(2)).And the introduction of MnO_(2)promoted the generation of atomic H^(*).Only adsorbed atomic hydrogen(H^(*)_(ads)) was confirmed that it truly facilitated the ECH process.Besides H^(*)_(ads) induced reduction,the direct reduction by cathode electrons also participated in the 2,4,6-TCP dechlorination process.Pd/MnO_(2)/Ni foam cathode shows excellent dechlorination performance,fine stability and recyclable potential,which provides strategies for the effective degradation of persistent halogenated organic pollutants in groundwater.展开更多
The floc morphology was investigated in a continuous-flow reactor, in order to understand the evolution of flocs in practical flocculation and sedimentation processes in water utilities. Kaolin-humic acid suspension w...The floc morphology was investigated in a continuous-flow reactor, in order to understand the evolution of flocs in practical flocculation and sedimentation processes in water utilities. Kaolin-humic acid suspension was used as the test water, and polyaluminum chloride was chosen as the coagulant. An in-situ recognition system was applied to analyze the floc size, boundary fractal dimension, and eccentricity ratios. Particle numbers and turbidity were also determined in the sedimentation stage. At a coagulant dose of 1 mg/L as Al, the average floc size increased from 62 to 78 μm and the boundary fractal dimension was around 1.14, suggesting that flocs were compact and continuously grew during the entire flocculation process. However, with the dose increased to 5 mg/L, the average floc size decreased and stabilized at around 65 μm, with the fractal dimension of 1.20. It can be concluded that the excess coagulant doses resulted in the formation of chain-shaped, lower density, and more branched structure flocs, thereby restricting flocs’ further growth in the subsequent flocculation. Floc morphology analysis suggested that charge neutralization dominated in the initial flocculation stage, then the bridge and sweep mechanisms were dominant in the subsequent flocculation. In addition, compared with the traditional inclined plate settler, a novel V-shaped plate settler introduced in this study had an advantage in small size floc(less than 5 μm) removal. The V-shaped region could promote aggregate restructuring and re-flocculation; therefore, the V-shaped plate settler provides an alternative method for sedimentation.展开更多
Three-dimensional fluorescence excitation–emission matrix(EEM) coupled with parallel factor analysis(PARAFAC) was performed for a total of 18 water samples taken from three water sources(two lakes and one wastew...Three-dimensional fluorescence excitation–emission matrix(EEM) coupled with parallel factor analysis(PARAFAC) was performed for a total of 18 water samples taken from three water sources(two lakes and one wastewater treatment plant(WWTP) secondary effluent),with the purpose of identifying the major ultrafiltration(UF) membrane foulants in different water sources. Three fluorescent components(C1, C2 and C3) were identified,which represented terrestrially derived humic-like substances(C1), microbially derived humic-like substances(C2), and protein-like substances(C3). The correlations between the different fluorescent components and UF membrane fouling were analyzed. It was shown that for the WWTP secondary effluent, all three components(C1, C2 and C3) made a considerable contribution to the irreversible and total fouling of the UF membrane.However, for the two lakes, only the C3 exhibited a strong correlation with membrane fouling, indicating that the protein-like substances were the major membrane foulants in the lake waters. Significant attachment of C1, C2 and C3 to the UF membrane was also confirmed by mass balance analyses for the WWTP secondary effluent; while the attachment of C1 and C2 was shown to be negligible for the two lakes. The results may provide basic formation for developing suitable fouling control strategies for sustainable UF processes.展开更多
The gravity-driven membrane bioreactor(MBR)system is promising for decentralized sewage treatment because of its low energy consumption and maintenance requirements.However,the growing sludge not only increases membra...The gravity-driven membrane bioreactor(MBR)system is promising for decentralized sewage treatment because of its low energy consumption and maintenance requirements.However,the growing sludge not only increases membrane fouling,but also augments operational complexities(sludge discharge).We added the metabolic uncoupler 3,3’,4f,5-tetrachlorosalicylanilide(TC$)to the system to deal with the mentioned issues.Based on the results,TCS addition effectively decreased sludge ATP and sludge yield(reduced by 50%).Extracellular polymeric substances(EPS;proteins and polysaccharides)decreased with the addition of TCS and were transformed into dissolved soluble microbial products(SMPs)in the bulk solution,leading to the break of sludge floes into small fragments.Permeability was increased by more than two times,reaching 60-70 L/m2/h bar when 10-30 mg/L TCS were added,because of the reduced suspended sludge and the formation of a thin cake layer with low EPS levels.Resistance analyses confirmed that appropriate dosages of TCS primarily decreased the cake layer and hydraulically reversible resistances.Permeability decreased at high dosage(50 mg/L)due to the release of excess sludge fragments and SMP into the supernatant,with a thin but more compact fouling layer with low bioactivity developing on the membrane surface,causing higher cake layer and pore blocking resistances.Our study provides a fundamental understanding of how a metabolic uncoupler affects the sludge and bio-fouling layers at different dosages,with practical relevance for in situ sludge reduction and membrane fouling alleviation in MBR systems.展开更多
Metal-organic frameworks(MOFs)materials with highly ordered and porous crystalline structure,have excellent performance in advanced oxidation progresses(AOPs)for organic contaminants degradation in water treatment.Thi...Metal-organic frameworks(MOFs)materials with highly ordered and porous crystalline structure,have excellent performance in advanced oxidation progresses(AOPs)for organic contaminants degradation in water treatment.This review intends to summarize the timely references and insights for the recent advances in MOFs that are used in AOPs.Starting with the preparation methodologies,including conventional hydrothermal method,electrochemical method,sol-gel method,and emerging microwave and ultrasound assisted synthesis methods.Application and mechanism for MOFs using in various AOPs of Fenton-like,photocatalysis,catalytic ozonation,persulfate catalysis and other emerging oxidation methods are emphatically discussed.We hope this review can comprehensively summarize the research and application progress of MOFs in AOPs,deepen the understanding of the catalytic mechanisms.展开更多
Catalytic potential of carbon nanomaterials in peroxydisulfate(PDS)advanced oxidation systems for degradation of antibiotics remains poorly understood.This study revealed ordered mesoporous carbon(type CMK)acted as a ...Catalytic potential of carbon nanomaterials in peroxydisulfate(PDS)advanced oxidation systems for degradation of antibiotics remains poorly understood.This study revealed ordered mesoporous carbon(type CMK)acted as a superior catalyst for heterogeneous degradation of sulfadiazine(SDZ)in PDS sys-tem,with a first-order reaction kinetic constant(k)and total organic carbon(TOC)mineralization efficiency of 0.06 min^(–1) and 59.67%±3.4%within 60min,respectively.CMK catalyzed PDS system exhibited high degradation efficiencies of five other sulfonamides and three other types of antibiotics,verifying the broad-degradation capacity of antibiotics.Under neutral pH conditions,the optimal catalytic parameters were an initial SDZ concentration of 44.0mg/L,CMK dosage of 0.07g/L,and PDS dosage of 5.44mmol/L,respectively.X-ray photoelectron spectroscopy and Raman spectrum analysis confirmed that the defect structure at edge of CMK and oxygen-containing functional groups on surface of CMK were major active sites,contributing to the high catalytic activity.Free radical quenching analysis revealed that both SO_(4)•−and•OH were generated and participated in catalytic reaction.In addition,direct electron transfer by CMK to activate PDS also occurred,further promoting catalytic performance.Configuration of SDZ molecule was optimized using density functional theory,and the possible reaction sites in SDZ molecule were calculated using Fukui function.Combining ultra-high-performance liquid chromatography(UPLC)–mass spectrometry(MS)/MS analysis,three potential degradation pathways were proposed,including the direct removal of SO_(2)molecules,the 14S-17N fracture,and the 19C-20N and 19C-27N cleavage of the SDZ molecule.The study demonstrated that ordered mesoporous carbon could work as a feasible catalytic material for PDS advanced oxidation during removal of antibiotics from wastewater.展开更多
基金financially supported by the National Key R&D Program of China (2022YFA1503400)the National Natural Science Foundation of China (21991091)+2 种基金the Key Projects of Shandong Key R&D plan (2019JZZY010506)Taishan Scholar Foundation (tspd20210308)the Petro China Research and Development Projects (2020A-1816 and 2020A-1817)。
基金supported by the National Natural Science Foundation of China(Nos.21906088,51902169,52170039)the National Science Foundation for Post-doctoral Scientists of China(No.2021T140165)+3 种基金the Natural Science Foundation of Heilongjiang Province,China(No.LH2020B023)Department of Education Heilongjiang Province(No.135309338)University Nursing Program for Young Scholars with Creative Talents in Heilongjiang Province(Nos.UNPYSCT-2020068,UNPYSCT-2020067)the financial support by the Heilongjiang Provincial Key Laboratory of Surface Active Agent and Auxiliary(No.BMHXJKF009)。
文摘This study explored the catalytic mechanism and performance impacted by the materials ratio of Fe_(3)O_(4)-GO_(x) composites in three typical advanced oxidation processes(AOPs)of O_(3),peroxodisulfate(PDS)and photo-Fenton processes for tetracycline hydrochloride(TCH)degradation.The ratio of GO in the Fe_(3)O_(4)-GO_(x) composites exhibited different trends of degradation capacity in each AOPs based on different mechanisms.Fe_(3)O_(4)-rGO_(20wt%) exhibited the optimum catalytic performance which enhanced the ozone decomposition efficiency from 33.48%(ozone alone)to 51.83%with the major reactive oxygen species(ROS)of O_(2)·-.In PDS and photo-Fenton processes,Fe_(3)O_(4)-rGO_(5wt%) had the highest catalytic performance in PDS and H_(2)O_(2) decomposition for SO_(4)·–,and·OH generation,respectively.Compared with using PDS alone,PDS decomposition rate and TCH degradation rate could be increased by 5.97 and 1.73 times under Fe_(3)O_(4)-rGO_(5wt%) catalysis.In the photo-Fenton system,Fe_(3)O_(4)-rGO_(5wt%) with the best catalyst performance in H_(2)O_(2) decomposition,and TCH degradation rate increased by 2.02 times compared with blank group.Meantime,the catalytic mechanisms in those systems of that the ROS produced by conversion between Fe^(2+)/Fe^(3+)were also analyzed.
基金supported by the NSFC-JSPS joint research program(No.51961145202)the Natural Science Foundation of Heilongjiang Province,China(No.C2018035)。
文摘Pd modified electrodes possess problems such as easy agglomeration and low electrolytic ability,and the use of manganese dioxide(MnO_(2)) to facilitate Pd reduction of organic pollutants is just started.However,there is still a limited understanding of how to match the Pd load and MnO_(2) to realize optimal dechlorination efficiency at minimum cost.Here,a Pd/MnO_(2)/Ni foam cathode was successfully fabricated and applied for the efficient electrochemical dechlorination of 2,4,6-trichlorophenol(2,4,6-TCP).The optimal electrocatalytic hydrodechlorination(ECH)performance with 2,4,6-TCP dechlorination efficiency(92.58%in 180 min)was obtained when the concentration of PdCl_(2) precipitation was 1 mmol/L,the deposition time of MnO_(2) was 300 s and cathode potential was-0.8 V.Performance influenced by the exogenous factors(e.g.,initial pH and coexisted ions)were further investigated.It was found that the neutral pH was the most favorable for ECH and a reduction in dechlorination efficiency(6%~47.6%)was observed in presence of 5 mmol/L of NO_(2)^(-),NO_(3)^(-),S^(2-)or SO_(3)^(2-).Cyclic voltammetry(CV)and quenching experiments verified the existence of three hydrogen species on Pd surface,including adsorbed atomic hydrogen(H^(*)_(ads)),absorbed atomic hydrogen(H^(*)_(abs)),and molecular hydrogen(H_(2)).And the introduction of MnO_(2)promoted the generation of atomic H^(*).Only adsorbed atomic hydrogen(H^(*)_(ads)) was confirmed that it truly facilitated the ECH process.Besides H^(*)_(ads) induced reduction,the direct reduction by cathode electrons also participated in the 2,4,6-TCP dechlorination process.Pd/MnO_(2)/Ni foam cathode shows excellent dechlorination performance,fine stability and recyclable potential,which provides strategies for the effective degradation of persistent halogenated organic pollutants in groundwater.
基金supported by the National Science and Technology Major Project of Twelfth Five Years(Nos.2014ZX07201-012-2,2013ZX07201007-002)the National Innovation Team supported by the National Science Foundation of China(No.50821002)the State Key Laboratory of Urban Water Resource and Environment(Harbin Institute of Technology)(No.2012DX07)
文摘The floc morphology was investigated in a continuous-flow reactor, in order to understand the evolution of flocs in practical flocculation and sedimentation processes in water utilities. Kaolin-humic acid suspension was used as the test water, and polyaluminum chloride was chosen as the coagulant. An in-situ recognition system was applied to analyze the floc size, boundary fractal dimension, and eccentricity ratios. Particle numbers and turbidity were also determined in the sedimentation stage. At a coagulant dose of 1 mg/L as Al, the average floc size increased from 62 to 78 μm and the boundary fractal dimension was around 1.14, suggesting that flocs were compact and continuously grew during the entire flocculation process. However, with the dose increased to 5 mg/L, the average floc size decreased and stabilized at around 65 μm, with the fractal dimension of 1.20. It can be concluded that the excess coagulant doses resulted in the formation of chain-shaped, lower density, and more branched structure flocs, thereby restricting flocs’ further growth in the subsequent flocculation. Floc morphology analysis suggested that charge neutralization dominated in the initial flocculation stage, then the bridge and sweep mechanisms were dominant in the subsequent flocculation. In addition, compared with the traditional inclined plate settler, a novel V-shaped plate settler introduced in this study had an advantage in small size floc(less than 5 μm) removal. The V-shaped region could promote aggregate restructuring and re-flocculation; therefore, the V-shaped plate settler provides an alternative method for sedimentation.
基金supported by the National Natural Science Foundation of China(No.51208140)the National Water Pollution Control and Treatment Science and Technology Major Project of China(No.2012ZX07201002)
文摘Three-dimensional fluorescence excitation–emission matrix(EEM) coupled with parallel factor analysis(PARAFAC) was performed for a total of 18 water samples taken from three water sources(two lakes and one wastewater treatment plant(WWTP) secondary effluent),with the purpose of identifying the major ultrafiltration(UF) membrane foulants in different water sources. Three fluorescent components(C1, C2 and C3) were identified,which represented terrestrially derived humic-like substances(C1), microbially derived humic-like substances(C2), and protein-like substances(C3). The correlations between the different fluorescent components and UF membrane fouling were analyzed. It was shown that for the WWTP secondary effluent, all three components(C1, C2 and C3) made a considerable contribution to the irreversible and total fouling of the UF membrane.However, for the two lakes, only the C3 exhibited a strong correlation with membrane fouling, indicating that the protein-like substances were the major membrane foulants in the lake waters. Significant attachment of C1, C2 and C3 to the UF membrane was also confirmed by mass balance analyses for the WWTP secondary effluent; while the attachment of C1 and C2 was shown to be negligible for the two lakes. The results may provide basic formation for developing suitable fouling control strategies for sustainable UF processes.
基金This work was jointly supported by the National Natural Science Foundation of China(Grant No.51608150)the Open Project of State Key Laboratory of Urban Water Resource and Environment,Harbin Institute of Technology(No.ES201810-02)+3 种基金the Natural Science Foundation of Heilongjiang Province(No.E2017042)the Natural Science Foundation of Harbin(No.2017RAQXJ206)special support from the China Postdoctoral Fund(No.2018T110303)special support from the Heilongjiang Postdoctoral Found(No.LBH-TZ14).
文摘The gravity-driven membrane bioreactor(MBR)system is promising for decentralized sewage treatment because of its low energy consumption and maintenance requirements.However,the growing sludge not only increases membrane fouling,but also augments operational complexities(sludge discharge).We added the metabolic uncoupler 3,3’,4f,5-tetrachlorosalicylanilide(TC$)to the system to deal with the mentioned issues.Based on the results,TCS addition effectively decreased sludge ATP and sludge yield(reduced by 50%).Extracellular polymeric substances(EPS;proteins and polysaccharides)decreased with the addition of TCS and were transformed into dissolved soluble microbial products(SMPs)in the bulk solution,leading to the break of sludge floes into small fragments.Permeability was increased by more than two times,reaching 60-70 L/m2/h bar when 10-30 mg/L TCS were added,because of the reduced suspended sludge and the formation of a thin cake layer with low EPS levels.Resistance analyses confirmed that appropriate dosages of TCS primarily decreased the cake layer and hydraulically reversible resistances.Permeability decreased at high dosage(50 mg/L)due to the release of excess sludge fragments and SMP into the supernatant,with a thin but more compact fouling layer with low bioactivity developing on the membrane surface,causing higher cake layer and pore blocking resistances.Our study provides a fundamental understanding of how a metabolic uncoupler affects the sludge and bio-fouling layers at different dosages,with practical relevance for in situ sludge reduction and membrane fouling alleviation in MBR systems.
基金supported by the National Natural Science Foundation of China(Nos.21906088,51902169,52170039)the National Science Foundation for Post-doctoral Scientists of China(No.2021T140165)+2 种基金the Heilongjiang Provincial Natural Science Foundation of China(No.LH2020B023)Department of Education Heilongjiang Province(Nos.135309338,135309351)University Nursing Program for Young Scholars with Creative Talents in Heilongjiang Province(Nos.UNPYSCT-2020068,UNPYSCT-2020067).
文摘Metal-organic frameworks(MOFs)materials with highly ordered and porous crystalline structure,have excellent performance in advanced oxidation progresses(AOPs)for organic contaminants degradation in water treatment.This review intends to summarize the timely references and insights for the recent advances in MOFs that are used in AOPs.Starting with the preparation methodologies,including conventional hydrothermal method,electrochemical method,sol-gel method,and emerging microwave and ultrasound assisted synthesis methods.Application and mechanism for MOFs using in various AOPs of Fenton-like,photocatalysis,catalytic ozonation,persulfate catalysis and other emerging oxidation methods are emphatically discussed.We hope this review can comprehensively summarize the research and application progress of MOFs in AOPs,deepen the understanding of the catalytic mechanisms.
基金supported by the NSFC-JSPS joint research pro-gram(No.51961145202)the Natural Science Foundation of Heilongjiang Province,China(No.C2018035).
文摘Catalytic potential of carbon nanomaterials in peroxydisulfate(PDS)advanced oxidation systems for degradation of antibiotics remains poorly understood.This study revealed ordered mesoporous carbon(type CMK)acted as a superior catalyst for heterogeneous degradation of sulfadiazine(SDZ)in PDS sys-tem,with a first-order reaction kinetic constant(k)and total organic carbon(TOC)mineralization efficiency of 0.06 min^(–1) and 59.67%±3.4%within 60min,respectively.CMK catalyzed PDS system exhibited high degradation efficiencies of five other sulfonamides and three other types of antibiotics,verifying the broad-degradation capacity of antibiotics.Under neutral pH conditions,the optimal catalytic parameters were an initial SDZ concentration of 44.0mg/L,CMK dosage of 0.07g/L,and PDS dosage of 5.44mmol/L,respectively.X-ray photoelectron spectroscopy and Raman spectrum analysis confirmed that the defect structure at edge of CMK and oxygen-containing functional groups on surface of CMK were major active sites,contributing to the high catalytic activity.Free radical quenching analysis revealed that both SO_(4)•−and•OH were generated and participated in catalytic reaction.In addition,direct electron transfer by CMK to activate PDS also occurred,further promoting catalytic performance.Configuration of SDZ molecule was optimized using density functional theory,and the possible reaction sites in SDZ molecule were calculated using Fukui function.Combining ultra-high-performance liquid chromatography(UPLC)–mass spectrometry(MS)/MS analysis,three potential degradation pathways were proposed,including the direct removal of SO_(2)molecules,the 14S-17N fracture,and the 19C-20N and 19C-27N cleavage of the SDZ molecule.The study demonstrated that ordered mesoporous carbon could work as a feasible catalytic material for PDS advanced oxidation during removal of antibiotics from wastewater.