The objective of the current research article is to provide a comprehensive review of excipients impact on the stability of the drug product and their implications during the product development. Recent developments i...The objective of the current research article is to provide a comprehensive review of excipients impact on the stability of the drug product and their implications during the product development. Recent developments in the understanding of the degradation pathways further impact methodologies used in the pharmaceutical industry for potential stability assessment. The formation of drug excipient adducts was very common based on the sensitive chemical moieties in the drugs and the excipients. The formation of the impurities was not limited to drug related impurities but there were several possibilities of the drug-excipient adduct formations as well as excipient impurities reaction with Active Pharmaceutical Ingredients. Identification of drug degradation in presence of excipients/excipient impurities requires extensive knowledge and adequate analytical characterization data. Systematic literature review and understanding about the drug formulation process, give you a smooth platform in establishing the finished product in the drug market. This paper discusses mechanistic basis of known drug-excipient interactions with case studies and provides an overview of common underlying themes in solid, semisolid and parenteral dosage forms.展开更多
In this study,complete tetracycline(TTC)and above 50%of total organic carbon(TOC)were removed by Fe S/PS after 30 min under optimized conditions.Although free radicals and high-valent iron ions were identified to gene...In this study,complete tetracycline(TTC)and above 50%of total organic carbon(TOC)were removed by Fe S/PS after 30 min under optimized conditions.Although free radicals and high-valent iron ions were identified to generate in the process,the apparent similarity between intermediate products of Fe S/PS,Fe/PS,and UV/PS systems demonstrated that the degradation of TTC was due to sulfate radicals(SO_(4)·^(-))and hydroxyl radicals(·OH).Based on the reaction between free radicals and organic matter,we speculated that TTC in the Fe S/PS system was decomposed and mineralized by dehydration,dehydrogenation,hydroxyl addition,demethylation,substitution,E-transfer,and ring-opening.Furthermore,a new understanding of Fe S-mediated PS activation based on stoichiometry and kinetic analysis showed that there were both homogeneous and heterogeneous reactions that occurred in the entire progress.However,due to the effect of p H on the dissolution of iron ions,the homogeneous reaction became the principal process with iron ions concentration exceeding 1.35 mg/L.This work provides a theoretical basis for the study of the degradation of TTC-containing wastewater by the iron-based advanced oxidation process.展开更多
In this study,novel iron-doped biochar(Fe-BC) was produced using a simple method,and it was used as an H_(2)O_(2)activator for tetracycline(TC) degradation.Generally,iron loading can improve the separation performance...In this study,novel iron-doped biochar(Fe-BC) was produced using a simple method,and it was used as an H_(2)O_(2)activator for tetracycline(TC) degradation.Generally,iron loading can improve the separation performance and reactivity of biochar(BC).In the Fe-BC/H_(2)O_(2)system,92% of the TC was removed within 30 min with the apparent rate constant(k_(obs)) of 0.155 min^(-1),which was 23.85 times that in the case of the BC/H_(2)O_(2)system(0.0065 min^(-1)).The effects of the H_(2)O_(2) and Fe-BC dosage,initial pH,and TC concentration on the TC removal were investigated.The radical quenching and electron paramagnetic resonance(EPR) measurements demonstrated that the removal of TC using the Fe-BC/H_(2)O_(2)process involved both radical(^(*)OH and O_(2)^(-)) and non-radical pathways(^(1)O_(2) and electron transfer).In addition,the performance of the catalyst was also affected by the persistent free radicals(PFRs) and defective sites on the catalyst.Moreover,the degradation pathways of TC were proposed according to the intermediate products detected by LC-MS and the ecotoxicity of intermediates was evaluated.Finally,the Fe-BC/H_(2)O_(2)showed high resistance to inorganic anions and natural organic matter in aquatic environments.Overall,Fe-BC is expected to be an economic and highly efficient heterogeneous Fenton catalyst for removing the organic contaminants in wastewater.展开更多
Triallyl isocyanurate(TAIC,C12H15N3O3)has featured in wastewater treatment as a refractory organic compound due to the significant production capability and negative environmental impact.TAIC degradation was enhanced ...Triallyl isocyanurate(TAIC,C12H15N3O3)has featured in wastewater treatment as a refractory organic compound due to the significant production capability and negative environmental impact.TAIC degradation was enhanced when an ozone(O3)/ultraviolet(UV)process was applied compared with the application of an independent O3 process.Although 99%of TAIC could be degraded in 5 min during both processes,the O3/UV process had a 70%mineralization rate that was much higher than that of the independent O3 process(9%)in 30 min.Four possible degradation pathways were proposed based on the organic compounds of intermediate products identified during TAIC degradation through the application of independent 03 and O3/UV processes.pH impacted both the direct and indirect oxidation processes.Acidic and alkaline conditions preferred direct and indirect reactions respectively,with a pH of 9 achieving maximum Total Organic Carbon(TOC)removal.Both CO32-and HCO3-decreased TOC removal,however only CO32-negatively impacted TAIC degradation.Effects of Cl-as a radical scavenger became more marked only at high concentrations(over 500 mg/L Cl-).Particulate and suspended matter could hinder the transmission of ultraviolet light and reduce the production of HO·accordingly.展开更多
As nitrobenzene(NB)is structurally stable and difficult to degrade due to the presence of an electron withdrawing group(nitro group).The sequential nanoscale zero valent iron-persulfate(NZVI-Na_(2)S_(2)O_(8))process w...As nitrobenzene(NB)is structurally stable and difficult to degrade due to the presence of an electron withdrawing group(nitro group).The sequential nanoscale zero valent iron-persulfate(NZVI-Na_(2)S_(2)O_(8))process was proposed in this study for the degradation NB-containing wastewater.The results showed that the NB degradation efficiency and the total organic carbon removal efficiency in the sequential NZVINa_(2)S_(2)O_(8)process were 100%and 49.25%,respectively,at a NB concentration of 200 mg L^(-1),a NZVI concentration of 0.75 g L^(-1),a Na_(2)S_(2)O_(8)concentration of 26.8 mmol L^(-1),an initial pH of 5,and a reaction time of 30 min,which were higher than those(88.53%and 35.24%,respectively)obtained in the NZVI/Na_(2)S_(2)O_(8)process.Sulfate radicals(SO_(4)·-)and hydroxyl radicals(·OH)generated in the reaction were identified directly by electron paramagnetic resonance spectroscopy and indirectly by radical capture experiments,and it was shown that both SO_(4)^(·-)and·OH played a major role in the sequential NZVI-Na_(2)S_(2)O_(8)process.The possible pathways involved in the reduction of NB to aniline(AN)and the further oxidative degradation of AN were determined by gas chromatography-mass spectrometry.展开更多
To understand the anaerobic degradation pathway of domestic sewage,three lab-scale upflow anaerobic sludge blanked reactors (UASB) were employed to study the degradation pathway of different particle size and the effe...To understand the anaerobic degradation pathway of domestic sewage,three lab-scale upflow anaerobic sludge blanked reactors (UASB) were employed to study the degradation pathway of different particle size and the effect of temperature on this process.Under the operation conditions of the hydraulic retention time of 24 h,the MLVSS of approximate 11200 mg·L-1 and the water temperature at 10,15 and 20℃,the overall degradation pathway of soluble fraction was characterized according to zero-order kinetics.As for the colloidal fraction (between 0.45 and 4.5 μm),the degradation processes followed a first-order kinetic,and should firstly disintegrated into soluble fraction before finally degrading.In contrast,suspended solids (bigger than 4.5 μm) degraded to soluble and colloidal fractions according to first-order kinetics,and the colloidal fraction originating from suspended solids further degraded into soluble fraction which had the same degradation kinetics as the original soluble fraction.There existed the difference of temperature effect on different fraction degradation.Under the temperature at 20,15 and 10 ℃,the first-order rate constant of suspended solids depredating into collide was 4.97,3.01 and 1.01 d-1 respectively.Whereas the degradation of collide to soluble fraction was slightly affected by the temperature change.On the other hand,the zero-order degradation rate constant of soluble fraction was 0.26,0.18 g and 0.12 gCOD·gVSS-1d-1,respectively.展开更多
In this research study, we have synthesized the bio-capped ZnO/g-C_(3)N_(4) nanocomposites by employing lemon juice(Citrus limon) as a stabilizer and mediator. Fruitfully, lemon juice which contains various acidic fun...In this research study, we have synthesized the bio-capped ZnO/g-C_(3)N_(4) nanocomposites by employing lemon juice(Citrus limon) as a stabilizer and mediator. Fruitfully, lemon juice which contains various acidic functional groups and citric acid has the capability to block the surface of g-C_(3)N_(4) from chemical reactivity and activated the surface of g-C_(3)N_(4) for various reactions. Consequently, the agglomeration behavior and controlled shape of g-C_(3)N_(4) has also been achieved. Our experimental results i.e. XRD,TEM, HRTEM, PL, FS, XPS, and PEC have confirmed that the lemon juice mediated and green g-C_(3)N_(4)(L-CN) have good performances and remarkable visible light photocatalytic activities as compared to the chemically synthesized g-C_(3)N_(4)(CN). Furthermore, the small surface area and low charge separation of g-C_(3)N_(4) is upgraded by coupling with Zn O nanoparticles. It is proved that the coupling of Zn O worked as a facilitator and photoelectron modulator to enhance the charge separation of g-C_(3)N_(4). Compared to pristine lemon-mediated green g-C_(3)N_(4)(L-CN), the most active sample 5Zn O/L-CN showed ~ 5-fold improvement in activities for ciprofloxacin(CIP) and methylene blue(MB) degradation. More specifically,the mineralization process and degradation pathways, and the mineralization process of ciprofloxacin(CIP) and methylene blue(MB) are suggested. Finally, our present novel research work will provide new access to synthesize the eco-friendly and bio-caped green g-C_(3)N_(4)nanomaterials and their employment for pollutants degradation and environmental purification.展开更多
Aromatic rice is considered an important commodity in the global market because of its strong aroma and eating and cooking quality.Asian countries,such as India and Pakistan,are the leading traders of Basmati rice,whe...Aromatic rice is considered an important commodity in the global market because of its strong aroma and eating and cooking quality.Asian countries,such as India and Pakistan,are the leading traders of Basmati rice,whereas Thailand is the major supplier of Jasmine rice in the international market.The strong aroma of rice is associated with more than 300 volatile compounds,among which 2-acetyl-1-pyrroline(2-AP)is the principal component.2-AP is a phenotypic expression of spontaneous mutations in the recessive gene OsBadh2 or Badh2.The present review focuses on the origin,evolution and diversity of genetic resources of aromatic rice available worldwide.A brief discussion is presented on the genes responsible for quality traits along with details of their molecular genetics.This compilation and discussion will be useful for future breeding programs and the biofortification of quality traits of aromatic rice to ensure food security and nutritional need.展开更多
As an active metabolite of venlafaxine and emerging antidepressant,Odesmethylvenlafaxine(ODVEN) was widely detected in different water bodies,which caused potential harm to human health and environmental safety.In thi...As an active metabolite of venlafaxine and emerging antidepressant,Odesmethylvenlafaxine(ODVEN) was widely detected in different water bodies,which caused potential harm to human health and environmental safety.In this study,the comparative work on the ODVEN degradation by UV(254 nm) and UV-LED(275 nm) activated sodium percarbonate(SPC) systems was systematically performed.The higher removal rate of ODVEN can be achieved under UV-LED direct photolysis(14.99%) than UV direct photolysis(4.57%) due to the higher values of photolysis coefficient at the wavelength 275nm.Significant synergistic effects were observed in the UV/SPC(80.38%) and UV-LED/SPC(53.57%) systems and the former exhibited better performance for the elimination of ODVEN.The degradation of ODVEN all followed the pseudo-first-order kinetics well in these processes,and the pseudo-first-order rate constant(kobs) increased with increasing SPC concentration.Radicals quenching experiments demonstrated that both ·OH and CO_(3)·-were involved in the degradation of ODVEN and the second-order rate constant of ODVEN with CO_(3)·-(1.58 × 10^(8)(mol/L)-1sec-1) was reported for the first time based on competitive kinetic method.The introduction of HA,Cl-,NO_(3)-and HCO_(3)-inhibited the ODVEN degradation to varying degrees in the both processes.According to quantum chemical calculation,radical addition at the ortho-position of the phenolic hydroxyl group was confirmed to be the main reaction pathways for the oxidation of ODVEN by·OH.In addition,the oxidation of ODVEN may involve the demethylation,H-abstraction,OH^(-)addition and C-N bond cleavage.Eventually,the UV-LED/SPC process was considered to be more cost-effective compared to the UV/SPC process,although the UV/SPC process possessed a higher removal rate of ODVEN.展开更多
As a common insecticide,nitenpyram(NTP)seriously threatens the human health and environmental safety.In this work,a visible-light-responsive photocata-lyst two-dimensional(2D)Bi_(2)WO_(6) was synthesized and applied t...As a common insecticide,nitenpyram(NTP)seriously threatens the human health and environmental safety.In this work,a visible-light-responsive photocata-lyst two-dimensional(2D)Bi_(2)WO_(6) was synthesized and applied to degrade NTP.Compared with bulk Bi_(2)WO_(6),the 2D Bi_(2)WO_(6)exhibits better photocatalytic performance for NTP degradation under visible-light irradiation.The enhanced activity can be ascribed to the unique 2D struc-ture which would induce to higher efficiency of carrier separation.Moreover,hole(h+)plays a major role(and·O^(2-))in the degradation of NTP.Based on the interme-diates detected by high-performance liquid chromatogra-phy-mass spectrometry(HPLC-MS),the degradation pathway of NTP was proposed.In addition,the influence of typical environmental factors(pH,water matrix,inorganic cations and common anions)on the degradation of NTP was also investigated.This work not only helps people to understand the degradation of pesticides in actual water bodies,but also provides reference for the subsequent treatment of agricultural wastewater.展开更多
Developing a high-quality photoelectrode for photoelectrochemical applications is still an ongoing challenge. In this study, we prepared the g-C_(3)N_(4) film on the indium tin oxide(ITO) glass through conventional co...Developing a high-quality photoelectrode for photoelectrochemical applications is still an ongoing challenge. In this study, we prepared the g-C_(3)N_(4) film on the indium tin oxide(ITO) glass through conventional coating, liquid-based growth, in-situ calcination, and vapor deposition methods, respectively. These electrodes were characterized and used as photoanodes to degrade methylene blue(MB) in water. Among these methods, the in-situ calcination method was most appropriate for preparing the continuous and organized g-C_(3)N_(4) film electrodes with uniform g-C_(3)N_(4) coverage and strong adhesion to the ITO substrate.It also had the highest activity in the photocatalytic(PC), electrochemical(EC), and photoelectrocatalytic(PEC) degradation processes of MB. In the PEC reaction, at an applied potential of 1.0 V and a light intensity of 0.96 W/cm^(2), the removal rate of MB was 62.5%, which was much higher than those in the PC and EC reactions. The high degradation rate was due to the synergistic effect of PEC degradation, wherein the PC and EC reactions promote and optimize each other. In the PC reaction, MB was degraded by-CH_(3) elimination, while the EC degradation pathway mainly included the conversion of sulfhydryl into sulfoxide and the opening of the central aromatic ring. Both methyl loss and aromatic ring opening occurred in the PEC reaction. Moreover, some monocyclic compounds were formed, and MB showed more complete degradation in the PEC reaction.展开更多
Photocatalysis is considered as an effective technique for mitigating ecological risks posed by residual tetracycline(TC).To improve the efficiency of this technique,it is necessary to enable photocatalysts to produce...Photocatalysis is considered as an effective technique for mitigating ecological risks posed by residual tetracycline(TC).To improve the efficiency of this technique,it is necessary to enable photocatalysts to produce highly reactive species,such as singlet oxygen(1O2).However,due to the high activation energy of 1O2,photocatalysts can hardly produce 1O2 without assistance from external oxidants.Herein,we find that the size-reducedα-Fe_(2)O_(3)nanoparticles(~4 nm)that anchored on g-C_(3)N_(4)nanotube(α-Fe_(2)O_(3)@CNNT)can spontaneously generate ^(1)O_(2) for degradation of TC.In comparison,only hydroxyl radical(·OH)can be produced by g-C_(3)N_(4)nanotube loaded with~14 nmα-Fe_(2)O_(3)nanoparticles(α-Fe_(2)O_(3)/CNNT).Owing to the high reactivity of the ^(1)O_(2) species,the photocatalytic degradation rate(Kapp)of TC withα-Fe_(2)O_(3)@CNNT(0.056 min^(−1))was 1.8 times higher than that ofα-Fe_(2)O_(3)/CNNT.The experimental results and theoretical calculations suggested that reducing the size ofα-Fe_(2)O_(3)nanoparticles anchored on g-C_(3)N_(4)nanotube decreased the surface electron density ofα-Fe_(2)O_(3),which induces the generation of high-valent Fe(IV)active sites overα-Fe_(2)O_(3)@CNNT and turns the degradation pathway into a unique ^(1)O_(2) dominated process.This study provides a new insight on the generation of ^(1)O_(2) for effective degradation of environmental pollutant.展开更多
The monoaminotrinitro iron phthalocyanine(FeMATNPc)is used to connect with isonicotinic acid(INA)for amide bonding and axial coordination to synthetic a unique catalyst FeMATNPc-INA,which is loaded in polyacrylonitril...The monoaminotrinitro iron phthalocyanine(FeMATNPc)is used to connect with isonicotinic acid(INA)for amide bonding and axial coordination to synthetic a unique catalyst FeMATNPc-INA,which is loaded in polyacrylonitrile(PAN)nanofibers by electrospinning.The introduction of INA destroys theπ-πconjugated stack structure in phthalocyanine molecules and exposes more active sites.The FeMATNPc-INA structure is characterized by X-ray photoelectron spectroscopy and UV-visible absorption spectrum,and the FeMATNPcINA/PAN structure is characterized by Fourier transform infrared spectroscopy and X-ray diffraction.The FeMATNPc-INA/PAN can effectively activate peroxymonosulfate(PMS)to eliminate carbamazepine(CBZ)within 40 minutes(PMS 1.5 mmol/L)in the dark.The effects of catalyst dosage,PMS concentration,pH and inorganic anion on the degradation of CBZ are investigated.It has been confirmed by electron paramagnetic resonance,gas chromatography–mass spectroscopy and free radical capture experiments that the catalytic system is degraded by·OH,SO4^(·-)and Fe(IV)=O are the major active species,the singlet oxygen(^(1)O_(2))is the secondary active species.The degradation process of CBZ is analyzed by ultra-high performance liquid chromatography-mass spectrometry and the aromatic compounds have been degraded to small molecular acids.展开更多
Effectiveness of pulsed power plasma for the degradation of two toxic volatile organic compounds(VOCs),toluene and methyl isobutyl ketone(MIBK),in aqueous solution was evaluated.The plasma degradation of MIBK has been...Effectiveness of pulsed power plasma for the degradation of two toxic volatile organic compounds(VOCs),toluene and methyl isobutyl ketone(MIBK),in aqueous solution was evaluated.The plasma degradation of MIBK has been studied for the first time.The influence of initial concentration of target compound,solution pH and scavengers on percentage degradation was evaluated.100%removal of 200 mg/L of toluene and MIBK was achieved both in liquid and gaseous phases after 12 and 16 min of plasma treatment,respectively.The first order rate constant of toluene and MIBK degradation(for 200 mg/L each)was 0.421 and 0.319 min~(-1)respectively when they were treated individually,and these values decreased slightly during degradation of their mixture.MIBK degradation was slower than toluene and it might be due to semi volatile and hydrophilic nature of MIBK.The effect of initial concentration of toluene and MIBK showed different degradation patterns.Highest degradation of both the compounds was obtained in neutral pH and in absence of scavengers.·OH radical was the major reactive species involved in their degradation.Their degradation in real environmental matrices showed that removal reduced significantly in secondary effluent due to scavenging of reactive species by various ions and organic matter.The total number of degradation intermediates identified in case of toluene and MIBK was 11 and 14 respectively and formate was the one recalcitrant byproduct generated.The degradation pathway of toluene and MIBK involving reactions of reactive oxygen and nitrogen species and reductive species is proposed.展开更多
As a novel alternative to traditional perfluoroalkyl substances(PFASs),including perfluorooctanoic acid(PFOA)and perfluorooctane sulfonate(PFOS),hexafluoroproplyene oxide trimer acid(HFPO-TA)has been detected worldwid...As a novel alternative to traditional perfluoroalkyl substances(PFASs),including perfluorooctanoic acid(PFOA)and perfluorooctane sulfonate(PFOS),hexafluoroproplyene oxide trimer acid(HFPO-TA)has been detected worldwide in surface water.Moreover,recent researches have demonstrated that HFPO-TA has stronger bioaccumulation potential and higher hepatotoxicity than PFOA.To treat these contaminants e.g.PFOA and PFOS,some photochemical techniques by adding exogenous substances had been reported.However,there is still no report for the behavior of HFPO-TA itself under direct UV irradiation.The current study investigated the photo-transformation of HFPO-TA under UV irradiation in aqueous solution.After 72 hr photoreaction,75%degradation ratio and 25%defluorination ratio were achieved under ambient condition.Reducing active species,i.e.,hydrated electrons and active hydrogen atoms,generated from water splitting played dominant roles in degradation of HFPO-TA,which was confirmed by different effects of reaction atmospheres and quenching experiments.A possible degradation pathway was proposed based on the products identification and theoretical calculations.In general,HFPO-TA would be transformed into shorter-chain PFASs,including hexafluoropropylene oxide dimer acid(HFPODA),perfluoropropionic acid(PFA)and trifluoroacetate(TFA).This research provides basic information for HFPO-TA photodegradation process and is essential to develop novel remediation techniques for HFPO-TA and other alternatives with similar structures.展开更多
Chlorophenols(CPs) have drawn great attention due to their high toxicity and ubiquitous presence in the environment. However,the practical application of anaerobic biodegradation to remove CPs is limited by low degrad...Chlorophenols(CPs) have drawn great attention due to their high toxicity and ubiquitous presence in the environment. However,the practical application of anaerobic biodegradation to remove CPs is limited by low degradation rate and incomplete mineralization. This work aims to apply a single-stage anaerobic fixed-bed bioreactor(An FBR) for complete anaerobic dechlorination and mineralization of CPs. Results showed that 2-CP removal efficiency of 99.4%, chemical oxygen demand(COD)removal efficiency of 93.0%, and methane yield of 0.22 L-CH4/g-COD could be obtained for a wide range of 2-CP loading rates(3.6–18.2 mmol L–1 d–1). Nearly complete anaerobic mineralization of 2-CP was achieved even in the absence of co-substrates,thereby greatly reducing the operation cost. This may be partly related to the attached-growth microorganisms in An FBR,allowing a higher biomass concentration and longer biomass retention time for enhanced 2-CP removal. Moreover, 16 S r RNA gene sequence analysis suggests that the An FBR harbored the potential dechlorinators(e.g., Anaeromyxobacter), phenoldegrading microbes(e.g., Comamonas and Syntrophobacter), and methanogens(e.g., Methanobacterium and Methanosaeta)after acclimation, which could cooperate effectively for 2-CP dechlorination and mineralization. Based on the identified intermediates, the possible mineralization pathway of 2-CP was proposed. These findings should be valuable to facilitate the engineering applications of An FBRs for removing CPs from wastewater.展开更多
Widespread use of azole fungicides and low removal efficiency in wastewater treatment plants(WWTPs) have led to the elevated concentration of azole fungicides in receiving environment. However, there was limited resea...Widespread use of azole fungicides and low removal efficiency in wastewater treatment plants(WWTPs) have led to the elevated concentration of azole fungicides in receiving environment. However, there was limited research about the removal mechanism of azole fungicides in the biological treatment of WWTPs. Imidazole fungicide climbazole and triazole fungicide fluconazole were selected to investigate the biodegradation mechanism of azole fungicides in activated sludge under aerobic conditions. Climbazole was found to be adsorbed to solid sludge and resulted in quick biodegradation. The degradation of climbazole in the aerobic activated sludge system was fitted well by the first-order kinetic model with a half-life of 5.3 days, while fluconazole tended to stay in liquid and had only about 30% of loss within 77 days incubation. Ten biotransformation products of climbazole were identified by high resolution mass spectrometry using suspect and non-target screening method. But no biodegradation products of fluconazole were identified due to its limited removal. The possible biodegradation pathways for climbazole were proposed based on the products identification and pathway prediction system, and involves oxidative dehalogenation, side chain oxidation and azole ring loss. The findings from this study suggest that it should be a concern for the persistence of fluconazole in the environment.展开更多
The difficulty in Fe(Ⅲ)/Fe(Ⅱ) conversion in the Fe(Ⅲ)/peroxymonosulfate(PMS) process limits its efficiency and application.Herein,L-cysteine(Cys),a green natural organic ligand with reducing capability,was innovati...The difficulty in Fe(Ⅲ)/Fe(Ⅱ) conversion in the Fe(Ⅲ)/peroxymonosulfate(PMS) process limits its efficiency and application.Herein,L-cysteine(Cys),a green natural organic ligand with reducing capability,was innovatively introduced into Fe(Ⅲ)/PMS to construct an excellent Cys/Fe(Ⅲ)/PMS process.The Cys/Fe(Ⅲ)/PMS process,at room temperature,can degrade a variety of organic contaminants,including dyes,phenolic compounds,and pharmaceuticals.In subsequent experiments with acid orange 7(A07),the AO7 degradation efficiency followed pseudo-first-order kinetic which exhibited an initial "fast stage" and a second "slow stage".The rate constant values ranged depending on the initial Cys,Fe(Ⅲ),PMS,and AO7 concentrations,reaction temperature,and pH values.In addition,the presence of Cl^(-),NO_(3)^(-),and SO_(4)^(2-) had negligible impact while HCO_(3)^(-) and humic acid inhibited the degradation of AO7.Furthermore,radical scavenger experiments and methyl phenyl sulfoxide(PMSO) transformation assay indicated that sulfate radical,hydroxyl radical,and ferryl ion(Fe(Ⅳ)) were the dominant reactive species involved in the Cys/Fe(Ⅲ)/PMS process.Finally,based on the results of gas chromatography-mass spectrometry,several AO7 degradation pathways,including N=N cleavage,hydroxylation,and ring opening were proposed.This study provided a new insight to improve the efficiency of Fe(Ⅲ)/PMS process by accelerating Fe(Ⅲ)/Fe(Ⅱ)cycle with Cys.展开更多
This study aimed to construct a photoelectrocatalytic(PEC)reaction system based on the self-made reduced TiO_(2) NTAs(r-TNAs)photoanode and activated carbon/Polytetrafluoroethylene(AC/PTFE)cathode.It would be observed...This study aimed to construct a photoelectrocatalytic(PEC)reaction system based on the self-made reduced TiO_(2) NTAs(r-TNAs)photoanode and activated carbon/Polytetrafluoroethylene(AC/PTFE)cathode.It would be observed clearly that the degradation rate constant of carbamazepine(CBZ)over r-TNAs(photoanode)-AC/PTFE(cathode)PEC system(0.04961 min^(-1))was even higher than that of r-TNAs(photoanode)-Pt(cathode)PEC system(0.04602 min^(-1))with the assistance of visible light irradiation and+0.4 V external potential.Besides,in order to obtain optimized conditions,the influence of key parameters such as pH value,electric current density and electrolyte concentration were studied.Most impo rtantly,photoelectrochemical(PECH)properties,reactive oxide species contribution.OH formation rate and CBZ degradation pathway were determined.The results illustrated that the excellent PEC degradation performance depended on the excellent photocatalytic property of r-TNAs photoanode and electron transfer prope rty of photoelectrodes in r-TNAs(photoanode)-AC/PTFE(cathode)PEC system.Therefo re,the study demonstrated that the r-TNAs(photoanode)-AC/PTFE(cathode)PEC system could be expected to replace metal-catalyzed cathodes depending on its excellent PEC performance activity and low cost as well as the reaction system possessed objective and practical application prospect.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
文摘The objective of the current research article is to provide a comprehensive review of excipients impact on the stability of the drug product and their implications during the product development. Recent developments in the understanding of the degradation pathways further impact methodologies used in the pharmaceutical industry for potential stability assessment. The formation of drug excipient adducts was very common based on the sensitive chemical moieties in the drugs and the excipients. The formation of the impurities was not limited to drug related impurities but there were several possibilities of the drug-excipient adduct formations as well as excipient impurities reaction with Active Pharmaceutical Ingredients. Identification of drug degradation in presence of excipients/excipient impurities requires extensive knowledge and adequate analytical characterization data. Systematic literature review and understanding about the drug formulation process, give you a smooth platform in establishing the finished product in the drug market. This paper discusses mechanistic basis of known drug-excipient interactions with case studies and provides an overview of common underlying themes in solid, semisolid and parenteral dosage forms.
基金supported by the National Natural Science Foundation of China(No.21876130)Natural Science Foundation of Shanghai(No.18ZR1440800)。
文摘In this study,complete tetracycline(TTC)and above 50%of total organic carbon(TOC)were removed by Fe S/PS after 30 min under optimized conditions.Although free radicals and high-valent iron ions were identified to generate in the process,the apparent similarity between intermediate products of Fe S/PS,Fe/PS,and UV/PS systems demonstrated that the degradation of TTC was due to sulfate radicals(SO_(4)·^(-))and hydroxyl radicals(·OH).Based on the reaction between free radicals and organic matter,we speculated that TTC in the Fe S/PS system was decomposed and mineralized by dehydration,dehydrogenation,hydroxyl addition,demethylation,substitution,E-transfer,and ring-opening.Furthermore,a new understanding of Fe S-mediated PS activation based on stoichiometry and kinetic analysis showed that there were both homogeneous and heterogeneous reactions that occurred in the entire progress.However,due to the effect of p H on the dissolution of iron ions,the homogeneous reaction became the principal process with iron ions concentration exceeding 1.35 mg/L.This work provides a theoretical basis for the study of the degradation of TTC-containing wastewater by the iron-based advanced oxidation process.
基金supported by National Natural Science Foundation of China (No. 21906045)The 2020 Scientific Research Project for Postgraduates of Henan Normal University (No. YL202029)。
文摘In this study,novel iron-doped biochar(Fe-BC) was produced using a simple method,and it was used as an H_(2)O_(2)activator for tetracycline(TC) degradation.Generally,iron loading can improve the separation performance and reactivity of biochar(BC).In the Fe-BC/H_(2)O_(2)system,92% of the TC was removed within 30 min with the apparent rate constant(k_(obs)) of 0.155 min^(-1),which was 23.85 times that in the case of the BC/H_(2)O_(2)system(0.0065 min^(-1)).The effects of the H_(2)O_(2) and Fe-BC dosage,initial pH,and TC concentration on the TC removal were investigated.The radical quenching and electron paramagnetic resonance(EPR) measurements demonstrated that the removal of TC using the Fe-BC/H_(2)O_(2)process involved both radical(^(*)OH and O_(2)^(-)) and non-radical pathways(^(1)O_(2) and electron transfer).In addition,the performance of the catalyst was also affected by the persistent free radicals(PFRs) and defective sites on the catalyst.Moreover,the degradation pathways of TC were proposed according to the intermediate products detected by LC-MS and the ecotoxicity of intermediates was evaluated.Finally,the Fe-BC/H_(2)O_(2)showed high resistance to inorganic anions and natural organic matter in aquatic environments.Overall,Fe-BC is expected to be an economic and highly efficient heterogeneous Fenton catalyst for removing the organic contaminants in wastewater.
基金This work was supported by the Major Science and Technology Program for Water Pollution Control and Treatment of China(Nos.2018ZX07105004 and 2018ZX07105003).
文摘Triallyl isocyanurate(TAIC,C12H15N3O3)has featured in wastewater treatment as a refractory organic compound due to the significant production capability and negative environmental impact.TAIC degradation was enhanced when an ozone(O3)/ultraviolet(UV)process was applied compared with the application of an independent O3 process.Although 99%of TAIC could be degraded in 5 min during both processes,the O3/UV process had a 70%mineralization rate that was much higher than that of the independent O3 process(9%)in 30 min.Four possible degradation pathways were proposed based on the organic compounds of intermediate products identified during TAIC degradation through the application of independent 03 and O3/UV processes.pH impacted both the direct and indirect oxidation processes.Acidic and alkaline conditions preferred direct and indirect reactions respectively,with a pH of 9 achieving maximum Total Organic Carbon(TOC)removal.Both CO32-and HCO3-decreased TOC removal,however only CO32-negatively impacted TAIC degradation.Effects of Cl-as a radical scavenger became more marked only at high concentrations(over 500 mg/L Cl-).Particulate and suspended matter could hinder the transmission of ultraviolet light and reduce the production of HO·accordingly.
基金supported by the Specialized Research Fund for Sanjin Scholars Program of Shanxi Province(201707)Key Research and Development Plan of Shanxi Province(201903D321059)Shanxi Scholarship Council of China(HGKY2019071)。
文摘As nitrobenzene(NB)is structurally stable and difficult to degrade due to the presence of an electron withdrawing group(nitro group).The sequential nanoscale zero valent iron-persulfate(NZVI-Na_(2)S_(2)O_(8))process was proposed in this study for the degradation NB-containing wastewater.The results showed that the NB degradation efficiency and the total organic carbon removal efficiency in the sequential NZVINa_(2)S_(2)O_(8)process were 100%and 49.25%,respectively,at a NB concentration of 200 mg L^(-1),a NZVI concentration of 0.75 g L^(-1),a Na_(2)S_(2)O_(8)concentration of 26.8 mmol L^(-1),an initial pH of 5,and a reaction time of 30 min,which were higher than those(88.53%and 35.24%,respectively)obtained in the NZVI/Na_(2)S_(2)O_(8)process.Sulfate radicals(SO_(4)·-)and hydroxyl radicals(·OH)generated in the reaction were identified directly by electron paramagnetic resonance spectroscopy and indirectly by radical capture experiments,and it was shown that both SO_(4)^(·-)and·OH played a major role in the sequential NZVI-Na_(2)S_(2)O_(8)process.The possible pathways involved in the reduction of NB to aniline(AN)and the further oxidative degradation of AN were determined by gas chromatography-mass spectrometry.
基金Sponsored by the National Natural Science Foundation of China (Grant No.51078102)the National Water Special Project (Grant No.2008ZX07207-005-02)the Science and Technology Research Project of Education Department of Heilongjiang Province(Grant No.11551370)
文摘To understand the anaerobic degradation pathway of domestic sewage,three lab-scale upflow anaerobic sludge blanked reactors (UASB) were employed to study the degradation pathway of different particle size and the effect of temperature on this process.Under the operation conditions of the hydraulic retention time of 24 h,the MLVSS of approximate 11200 mg·L-1 and the water temperature at 10,15 and 20℃,the overall degradation pathway of soluble fraction was characterized according to zero-order kinetics.As for the colloidal fraction (between 0.45 and 4.5 μm),the degradation processes followed a first-order kinetic,and should firstly disintegrated into soluble fraction before finally degrading.In contrast,suspended solids (bigger than 4.5 μm) degraded to soluble and colloidal fractions according to first-order kinetics,and the colloidal fraction originating from suspended solids further degraded into soluble fraction which had the same degradation kinetics as the original soluble fraction.There existed the difference of temperature effect on different fraction degradation.Under the temperature at 20,15 and 10 ℃,the first-order rate constant of suspended solids depredating into collide was 4.97,3.01 and 1.01 d-1 respectively.Whereas the degradation of collide to soluble fraction was slightly affected by the temperature change.On the other hand,the zero-order degradation rate constant of soluble fraction was 0.26,0.18 g and 0.12 gCOD·gVSS-1d-1,respectively.
基金Jiangsu University of Science and Technology for providing financial support under the Research start-up fund for the introduction of young talent at Jiangsu University of Science and Technology (Grant no. 1112932205)High-level Talents Program of Shihezi University (RCZK2021B25)。
文摘In this research study, we have synthesized the bio-capped ZnO/g-C_(3)N_(4) nanocomposites by employing lemon juice(Citrus limon) as a stabilizer and mediator. Fruitfully, lemon juice which contains various acidic functional groups and citric acid has the capability to block the surface of g-C_(3)N_(4) from chemical reactivity and activated the surface of g-C_(3)N_(4) for various reactions. Consequently, the agglomeration behavior and controlled shape of g-C_(3)N_(4) has also been achieved. Our experimental results i.e. XRD,TEM, HRTEM, PL, FS, XPS, and PEC have confirmed that the lemon juice mediated and green g-C_(3)N_(4)(L-CN) have good performances and remarkable visible light photocatalytic activities as compared to the chemically synthesized g-C_(3)N_(4)(CN). Furthermore, the small surface area and low charge separation of g-C_(3)N_(4) is upgraded by coupling with Zn O nanoparticles. It is proved that the coupling of Zn O worked as a facilitator and photoelectron modulator to enhance the charge separation of g-C_(3)N_(4). Compared to pristine lemon-mediated green g-C_(3)N_(4)(L-CN), the most active sample 5Zn O/L-CN showed ~ 5-fold improvement in activities for ciprofloxacin(CIP) and methylene blue(MB) degradation. More specifically,the mineralization process and degradation pathways, and the mineralization process of ciprofloxacin(CIP) and methylene blue(MB) are suggested. Finally, our present novel research work will provide new access to synthesize the eco-friendly and bio-caped green g-C_(3)N_(4)nanomaterials and their employment for pollutants degradation and environmental purification.
基金University Grant Commission, New Delhi, India for providing Non-National Eligibility Test fellowship
文摘Aromatic rice is considered an important commodity in the global market because of its strong aroma and eating and cooking quality.Asian countries,such as India and Pakistan,are the leading traders of Basmati rice,whereas Thailand is the major supplier of Jasmine rice in the international market.The strong aroma of rice is associated with more than 300 volatile compounds,among which 2-acetyl-1-pyrroline(2-AP)is the principal component.2-AP is a phenotypic expression of spontaneous mutations in the recessive gene OsBadh2 or Badh2.The present review focuses on the origin,evolution and diversity of genetic resources of aromatic rice available worldwide.A brief discussion is presented on the genes responsible for quality traits along with details of their molecular genetics.This compilation and discussion will be useful for future breeding programs and the biofortification of quality traits of aromatic rice to ensure food security and nutritional need.
基金supported by the National Natural Science Foundation of China (Nos.51978618,51878582)the Natural Science Foundation of Zhejiang Province (Nos.LY21E080018,LY18E080036)+1 种基金Guiding Project of Fujian Province of China (No.2021Y0041)Foundation of Key Laboratory of Yangtze River Water Environment and Ministry of Education (Tongji University),China (No.YRWEF201901)。
文摘As an active metabolite of venlafaxine and emerging antidepressant,Odesmethylvenlafaxine(ODVEN) was widely detected in different water bodies,which caused potential harm to human health and environmental safety.In this study,the comparative work on the ODVEN degradation by UV(254 nm) and UV-LED(275 nm) activated sodium percarbonate(SPC) systems was systematically performed.The higher removal rate of ODVEN can be achieved under UV-LED direct photolysis(14.99%) than UV direct photolysis(4.57%) due to the higher values of photolysis coefficient at the wavelength 275nm.Significant synergistic effects were observed in the UV/SPC(80.38%) and UV-LED/SPC(53.57%) systems and the former exhibited better performance for the elimination of ODVEN.The degradation of ODVEN all followed the pseudo-first-order kinetics well in these processes,and the pseudo-first-order rate constant(kobs) increased with increasing SPC concentration.Radicals quenching experiments demonstrated that both ·OH and CO_(3)·-were involved in the degradation of ODVEN and the second-order rate constant of ODVEN with CO_(3)·-(1.58 × 10^(8)(mol/L)-1sec-1) was reported for the first time based on competitive kinetic method.The introduction of HA,Cl-,NO_(3)-and HCO_(3)-inhibited the ODVEN degradation to varying degrees in the both processes.According to quantum chemical calculation,radical addition at the ortho-position of the phenolic hydroxyl group was confirmed to be the main reaction pathways for the oxidation of ODVEN by·OH.In addition,the oxidation of ODVEN may involve the demethylation,H-abstraction,OH^(-)addition and C-N bond cleavage.Eventually,the UV-LED/SPC process was considered to be more cost-effective compared to the UV/SPC process,although the UV/SPC process possessed a higher removal rate of ODVEN.
基金financially supported by the National Natural Science Foundation of China (No. 51979081)the Fundamental Research Funds for the Central Universities (No. B200202103)+1 种基金the National Key Plan for Research and Development of China (No. 2016YFC0502203)the National Science Funds for Creative Research Groups of China (No. 51421006) and PAPD
文摘As a common insecticide,nitenpyram(NTP)seriously threatens the human health and environmental safety.In this work,a visible-light-responsive photocata-lyst two-dimensional(2D)Bi_(2)WO_(6) was synthesized and applied to degrade NTP.Compared with bulk Bi_(2)WO_(6),the 2D Bi_(2)WO_(6)exhibits better photocatalytic performance for NTP degradation under visible-light irradiation.The enhanced activity can be ascribed to the unique 2D struc-ture which would induce to higher efficiency of carrier separation.Moreover,hole(h+)plays a major role(and·O^(2-))in the degradation of NTP.Based on the interme-diates detected by high-performance liquid chromatogra-phy-mass spectrometry(HPLC-MS),the degradation pathway of NTP was proposed.In addition,the influence of typical environmental factors(pH,water matrix,inorganic cations and common anions)on the degradation of NTP was also investigated.This work not only helps people to understand the degradation of pesticides in actual water bodies,but also provides reference for the subsequent treatment of agricultural wastewater.
基金financial support from the National Natural Science Foundation of China(No.51978658)。
文摘Developing a high-quality photoelectrode for photoelectrochemical applications is still an ongoing challenge. In this study, we prepared the g-C_(3)N_(4) film on the indium tin oxide(ITO) glass through conventional coating, liquid-based growth, in-situ calcination, and vapor deposition methods, respectively. These electrodes were characterized and used as photoanodes to degrade methylene blue(MB) in water. Among these methods, the in-situ calcination method was most appropriate for preparing the continuous and organized g-C_(3)N_(4) film electrodes with uniform g-C_(3)N_(4) coverage and strong adhesion to the ITO substrate.It also had the highest activity in the photocatalytic(PC), electrochemical(EC), and photoelectrocatalytic(PEC) degradation processes of MB. In the PEC reaction, at an applied potential of 1.0 V and a light intensity of 0.96 W/cm^(2), the removal rate of MB was 62.5%, which was much higher than those in the PC and EC reactions. The high degradation rate was due to the synergistic effect of PEC degradation, wherein the PC and EC reactions promote and optimize each other. In the PC reaction, MB was degraded by-CH_(3) elimination, while the EC degradation pathway mainly included the conversion of sulfhydryl into sulfoxide and the opening of the central aromatic ring. Both methyl loss and aromatic ring opening occurred in the PEC reaction. Moreover, some monocyclic compounds were formed, and MB showed more complete degradation in the PEC reaction.
基金funded by the Project ZR2021QB123 supported by Shandong Provincial Natural Science Foundation,Liaocheng University Start-up Fund for Doctoral Scientific Research(No.318052017).
文摘Photocatalysis is considered as an effective technique for mitigating ecological risks posed by residual tetracycline(TC).To improve the efficiency of this technique,it is necessary to enable photocatalysts to produce highly reactive species,such as singlet oxygen(1O2).However,due to the high activation energy of 1O2,photocatalysts can hardly produce 1O2 without assistance from external oxidants.Herein,we find that the size-reducedα-Fe_(2)O_(3)nanoparticles(~4 nm)that anchored on g-C_(3)N_(4)nanotube(α-Fe_(2)O_(3)@CNNT)can spontaneously generate ^(1)O_(2) for degradation of TC.In comparison,only hydroxyl radical(·OH)can be produced by g-C_(3)N_(4)nanotube loaded with~14 nmα-Fe_(2)O_(3)nanoparticles(α-Fe_(2)O_(3)/CNNT).Owing to the high reactivity of the ^(1)O_(2) species,the photocatalytic degradation rate(Kapp)of TC withα-Fe_(2)O_(3)@CNNT(0.056 min^(−1))was 1.8 times higher than that ofα-Fe_(2)O_(3)/CNNT.The experimental results and theoretical calculations suggested that reducing the size ofα-Fe_(2)O_(3)nanoparticles anchored on g-C_(3)N_(4)nanotube decreased the surface electron density ofα-Fe_(2)O_(3),which induces the generation of high-valent Fe(IV)active sites overα-Fe_(2)O_(3)@CNNT and turns the degradation pathway into a unique ^(1)O_(2) dominated process.This study provides a new insight on the generation of ^(1)O_(2) for effective degradation of environmental pollutant.
基金supported by National Natural Science Foundation of China (No.22006136)。
文摘The monoaminotrinitro iron phthalocyanine(FeMATNPc)is used to connect with isonicotinic acid(INA)for amide bonding and axial coordination to synthetic a unique catalyst FeMATNPc-INA,which is loaded in polyacrylonitrile(PAN)nanofibers by electrospinning.The introduction of INA destroys theπ-πconjugated stack structure in phthalocyanine molecules and exposes more active sites.The FeMATNPc-INA structure is characterized by X-ray photoelectron spectroscopy and UV-visible absorption spectrum,and the FeMATNPcINA/PAN structure is characterized by Fourier transform infrared spectroscopy and X-ray diffraction.The FeMATNPc-INA/PAN can effectively activate peroxymonosulfate(PMS)to eliminate carbamazepine(CBZ)within 40 minutes(PMS 1.5 mmol/L)in the dark.The effects of catalyst dosage,PMS concentration,pH and inorganic anion on the degradation of CBZ are investigated.It has been confirmed by electron paramagnetic resonance,gas chromatography–mass spectroscopy and free radical capture experiments that the catalytic system is degraded by·OH,SO4^(·-)and Fe(IV)=O are the major active species,the singlet oxygen(^(1)O_(2))is the secondary active species.The degradation process of CBZ is analyzed by ultra-high performance liquid chromatography-mass spectrometry and the aromatic compounds have been degraded to small molecular acids.
基金the financial support received from Department of Science and Technology(DST),Government of India(Nos.DST/TM/WTI/WIC/2K17/82(G)and DST/CCP/Co E/141/2018(G))for this study。
文摘Effectiveness of pulsed power plasma for the degradation of two toxic volatile organic compounds(VOCs),toluene and methyl isobutyl ketone(MIBK),in aqueous solution was evaluated.The plasma degradation of MIBK has been studied for the first time.The influence of initial concentration of target compound,solution pH and scavengers on percentage degradation was evaluated.100%removal of 200 mg/L of toluene and MIBK was achieved both in liquid and gaseous phases after 12 and 16 min of plasma treatment,respectively.The first order rate constant of toluene and MIBK degradation(for 200 mg/L each)was 0.421 and 0.319 min~(-1)respectively when they were treated individually,and these values decreased slightly during degradation of their mixture.MIBK degradation was slower than toluene and it might be due to semi volatile and hydrophilic nature of MIBK.The effect of initial concentration of toluene and MIBK showed different degradation patterns.Highest degradation of both the compounds was obtained in neutral pH and in absence of scavengers.·OH radical was the major reactive species involved in their degradation.Their degradation in real environmental matrices showed that removal reduced significantly in secondary effluent due to scavenging of reactive species by various ions and organic matter.The total number of degradation intermediates identified in case of toluene and MIBK was 11 and 14 respectively and formate was the one recalcitrant byproduct generated.The degradation pathway of toluene and MIBK involving reactions of reactive oxygen and nitrogen species and reductive species is proposed.
基金funded by the Chinese Academy of Engineering Consulting Project(No.2019-XZ-24)the National Key Re-search and Development Plans of Special Project for Site Soil(No.2018YFC1801002)。
文摘As a novel alternative to traditional perfluoroalkyl substances(PFASs),including perfluorooctanoic acid(PFOA)and perfluorooctane sulfonate(PFOS),hexafluoroproplyene oxide trimer acid(HFPO-TA)has been detected worldwide in surface water.Moreover,recent researches have demonstrated that HFPO-TA has stronger bioaccumulation potential and higher hepatotoxicity than PFOA.To treat these contaminants e.g.PFOA and PFOS,some photochemical techniques by adding exogenous substances had been reported.However,there is still no report for the behavior of HFPO-TA itself under direct UV irradiation.The current study investigated the photo-transformation of HFPO-TA under UV irradiation in aqueous solution.After 72 hr photoreaction,75%degradation ratio and 25%defluorination ratio were achieved under ambient condition.Reducing active species,i.e.,hydrated electrons and active hydrogen atoms,generated from water splitting played dominant roles in degradation of HFPO-TA,which was confirmed by different effects of reaction atmospheres and quenching experiments.A possible degradation pathway was proposed based on the products identification and theoretical calculations.In general,HFPO-TA would be transformed into shorter-chain PFASs,including hexafluoropropylene oxide dimer acid(HFPODA),perfluoropropionic acid(PFA)and trifluoroacetate(TFA).This research provides basic information for HFPO-TA photodegradation process and is essential to develop novel remediation techniques for HFPO-TA and other alternatives with similar structures.
基金supported by the National Key Research and Development Program of China(Grant No.2016YFC0401101)the National Natural Science Foundation of China(Grant Nos.51738012,51708533,and51821006)+1 种基金the Key Research Program of Frontier Sciences,CAS(Grant No.QYZDB-SSWQDC020)the Fundamental Research Funds for the Central Universities(Grant No.WK2060190079)
文摘Chlorophenols(CPs) have drawn great attention due to their high toxicity and ubiquitous presence in the environment. However,the practical application of anaerobic biodegradation to remove CPs is limited by low degradation rate and incomplete mineralization. This work aims to apply a single-stage anaerobic fixed-bed bioreactor(An FBR) for complete anaerobic dechlorination and mineralization of CPs. Results showed that 2-CP removal efficiency of 99.4%, chemical oxygen demand(COD)removal efficiency of 93.0%, and methane yield of 0.22 L-CH4/g-COD could be obtained for a wide range of 2-CP loading rates(3.6–18.2 mmol L–1 d–1). Nearly complete anaerobic mineralization of 2-CP was achieved even in the absence of co-substrates,thereby greatly reducing the operation cost. This may be partly related to the attached-growth microorganisms in An FBR,allowing a higher biomass concentration and longer biomass retention time for enhanced 2-CP removal. Moreover, 16 S r RNA gene sequence analysis suggests that the An FBR harbored the potential dechlorinators(e.g., Anaeromyxobacter), phenoldegrading microbes(e.g., Comamonas and Syntrophobacter), and methanogens(e.g., Methanobacterium and Methanosaeta)after acclimation, which could cooperate effectively for 2-CP dechlorination and mineralization. Based on the identified intermediates, the possible mineralization pathway of 2-CP was proposed. These findings should be valuable to facilitate the engineering applications of An FBRs for removing CPs from wastewater.
基金supported by the National Natural Science Foundation of China(Nos.41473105,41877358 and 21806043)Scientific Research and Technology Development Program of Guangxi(No.2018AB36018)+1 种基金Guangdong Provincial Key Laboratory of Chemical Pollution and Environmental Safety(No.2019B030301008)the Pearl River Talent Plan of Guangdong Province(No.2017GC010244)。
文摘Widespread use of azole fungicides and low removal efficiency in wastewater treatment plants(WWTPs) have led to the elevated concentration of azole fungicides in receiving environment. However, there was limited research about the removal mechanism of azole fungicides in the biological treatment of WWTPs. Imidazole fungicide climbazole and triazole fungicide fluconazole were selected to investigate the biodegradation mechanism of azole fungicides in activated sludge under aerobic conditions. Climbazole was found to be adsorbed to solid sludge and resulted in quick biodegradation. The degradation of climbazole in the aerobic activated sludge system was fitted well by the first-order kinetic model with a half-life of 5.3 days, while fluconazole tended to stay in liquid and had only about 30% of loss within 77 days incubation. Ten biotransformation products of climbazole were identified by high resolution mass spectrometry using suspect and non-target screening method. But no biodegradation products of fluconazole were identified due to its limited removal. The possible biodegradation pathways for climbazole were proposed based on the products identification and pathway prediction system, and involves oxidative dehalogenation, side chain oxidation and azole ring loss. The findings from this study suggest that it should be a concern for the persistence of fluconazole in the environment.
基金supported by the Natural Science Foundation of Jiangsu Province,China (No. BK20200721)the Natural Science Foundation of the Higher Education Institutions of Jiangsu Province,China (No. 19KJB610016)+2 种基金the National Natural Science Foundation of China (No. 21777067)the Six Talent Peaks Project in Jiangsu Province,China (No. JNHB–10)Primary Research&Development Plan of Jiangsu Province,China (No. BE2019743)。
文摘The difficulty in Fe(Ⅲ)/Fe(Ⅱ) conversion in the Fe(Ⅲ)/peroxymonosulfate(PMS) process limits its efficiency and application.Herein,L-cysteine(Cys),a green natural organic ligand with reducing capability,was innovatively introduced into Fe(Ⅲ)/PMS to construct an excellent Cys/Fe(Ⅲ)/PMS process.The Cys/Fe(Ⅲ)/PMS process,at room temperature,can degrade a variety of organic contaminants,including dyes,phenolic compounds,and pharmaceuticals.In subsequent experiments with acid orange 7(A07),the AO7 degradation efficiency followed pseudo-first-order kinetic which exhibited an initial "fast stage" and a second "slow stage".The rate constant values ranged depending on the initial Cys,Fe(Ⅲ),PMS,and AO7 concentrations,reaction temperature,and pH values.In addition,the presence of Cl^(-),NO_(3)^(-),and SO_(4)^(2-) had negligible impact while HCO_(3)^(-) and humic acid inhibited the degradation of AO7.Furthermore,radical scavenger experiments and methyl phenyl sulfoxide(PMSO) transformation assay indicated that sulfate radical,hydroxyl radical,and ferryl ion(Fe(Ⅳ)) were the dominant reactive species involved in the Cys/Fe(Ⅲ)/PMS process.Finally,based on the results of gas chromatography-mass spectrometry,several AO7 degradation pathways,including N=N cleavage,hydroxylation,and ring opening were proposed.This study provided a new insight to improve the efficiency of Fe(Ⅲ)/PMS process by accelerating Fe(Ⅲ)/Fe(Ⅱ)cycle with Cys.
基金National Natural Science Foundation of China(Nos.51508254,51978319)Fundamental Research Funds for the Central Universities(No.lzujblky-2017-it98)+1 种基金National College Student Innovation and Entrepreneurship Training Program of Lanzhou UniversityKey Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources,Qinghai Institute of Salt Lake,Chinese Academy of Sciences。
文摘This study aimed to construct a photoelectrocatalytic(PEC)reaction system based on the self-made reduced TiO_(2) NTAs(r-TNAs)photoanode and activated carbon/Polytetrafluoroethylene(AC/PTFE)cathode.It would be observed clearly that the degradation rate constant of carbamazepine(CBZ)over r-TNAs(photoanode)-AC/PTFE(cathode)PEC system(0.04961 min^(-1))was even higher than that of r-TNAs(photoanode)-Pt(cathode)PEC system(0.04602 min^(-1))with the assistance of visible light irradiation and+0.4 V external potential.Besides,in order to obtain optimized conditions,the influence of key parameters such as pH value,electric current density and electrolyte concentration were studied.Most impo rtantly,photoelectrochemical(PECH)properties,reactive oxide species contribution.OH formation rate and CBZ degradation pathway were determined.The results illustrated that the excellent PEC degradation performance depended on the excellent photocatalytic property of r-TNAs photoanode and electron transfer prope rty of photoelectrodes in r-TNAs(photoanode)-AC/PTFE(cathode)PEC system.Therefo re,the study demonstrated that the r-TNAs(photoanode)-AC/PTFE(cathode)PEC system could be expected to replace metal-catalyzed cathodes depending on its excellent PEC performance activity and low cost as well as the reaction system possessed objective and practical application prospect.
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.
