2,4,6-trichlorophenol (TCP) was firstly treated with air ions generated by electric discharge, and high dechlorination (53%) was observed after 60 min treatment, indicating that air ions are an efficient dechlorinatio...2,4,6-trichlorophenol (TCP) was firstly treated with air ions generated by electric discharge, and high dechlorination (53%) was observed after 60 min treatment, indicating that air ions are an efficient dechlorination means and might have a future in the oxidative removal of chlorinated phenols. In addition, a stepwise degradation of TCP, beginning with the formation of a major product 2,6-dichloro-1,4-benzenediol via substitution, is proposed through a detailed analysis of gas chromatography/mass spectrometry.展开更多
The reaction mechanism and pathway of the ozonation of 2,4,6-trichlorophenol(2,4,6-TCP)in aqueous solution were investigated.The removal efficiency and the variation of H_(2)O_(2),Cl^(−),formic acid,and oxalic acid we...The reaction mechanism and pathway of the ozonation of 2,4,6-trichlorophenol(2,4,6-TCP)in aqueous solution were investigated.The removal efficiency and the variation of H_(2)O_(2),Cl^(−),formic acid,and oxalic acid were studied during the semi-batch ozonation experiments(con-tinuous for ozone gas supply,fixed volume of water sample).The results showed that when there was no scavenger,the removal efficiency of 0.1 mmol/L 2,4,6-TCP could reach 99%within 6 min by adding 24 mg/L ozone.The reaction of molecular ozone with 2,4,6-TCP resulted in the formation of H2O2.The maximal concentration of H_(2)O_(2) detected during the ozonation could reach 22.5%of the original concentration of 2,4,6-TCP.The reaction of ozone with H_(2)O_(2) resulted in the generation of a lot of OH·radicals.Therefore,2,4,6-TCP was degraded to formic acid and oxalic acid by ozone and OH·radicals together.With the inhibition of OH·radicals,ozone molecule firstly degraded 2,4,6-TCP to form chlorinated quinone,which was subsequently oxidized to formic acid and oxalic acid.Two reaction pathways of the degradation of 2,4,6-TCP by ozone and O_(3)/OH·were proposed in this study.展开更多
Photocatalytic hydrogen production synergized with the oxidation of pollutants is an environmentally friendly and economical approach to generate clean energy and remove the pollution from environment.In this study,ph...Photocatalytic hydrogen production synergized with the oxidation of pollutants is an environmentally friendly and economical approach to generate clean energy and remove the pollution from environment.In this study,photocatalytic hydrogen production cooperating with 2,4,6-trichlorophenol(2,4,6-TCP)degradation have been reinforced by introducing an ultrasonic atomization.The degradation of 2,4,6-TCP in a mist of three photocatalysts(g-C3N4,TiO2,and Bi2O3)generated by ultrasonic atomization was performed under 254 nm ultraviolet(UV254)light irradiation.The results showed that,under UV254 irradiation,three different photocatalysts(g-C3N4,TiO2,and Bi2O3)all accelerated both hydrogen production and 2,4,6-TCP degradation.Additionally,2,4,6-TCP degradation and photocatalytic hydrogen production exhibited an obvious synergistic effect,since 2,4,6-TCP has a strong tendency to react with photo-generated holes and their second radicals so as to inhibit the recombination of carriers,and thus improved the efficiency of hydrogen production simultaneously.Moreover,by introducing ultrasonic atomization,the atomized droplets acted as micro-photocatalytic units to replace the macrophotocatalytic reaction reactor.Therefore,the mass transfer distance for free radicals was restricted and the utilization of light energy by photocatalysts was increased.Further,the reaction efficiency was improved.The results reveal environmentally friendly and economical potential of hydrogen production by photocatalytic degradation of 2,4,6-TCP in atomized droplets.展开更多
采用改进的两步法在原位基础上合成了以纳米零价铁(nano Zero Valent Iron,nZVI)为核芯的核壳型介孔二氧化硅(nZVI@mesoSiO_2).同时,通过简单地调控铁源用量得到具有单一nZVI核芯和不同壳层厚度的核壳型纳米复合材料.结果发现,铁源用量...采用改进的两步法在原位基础上合成了以纳米零价铁(nano Zero Valent Iron,nZVI)为核芯的核壳型介孔二氧化硅(nZVI@mesoSiO_2).同时,通过简单地调控铁源用量得到具有单一nZVI核芯和不同壳层厚度的核壳型纳米复合材料.结果发现,铁源用量的增加会导致核芯尺寸减小、壳层厚度增加及颗粒比表面积下降.当铁源用量为2.78 g时,得到的nZVI@mesoSiO_2不仅具有较高的比表面积和单一且均匀的孔径分布,而且对2,4,6-三氯苯酚(2,4,6-Trichlorophenol, 2,4,6-TCP)的去除表现出很高的性能.影响因素实验表明,材料的最佳投加量为1.0 g·L^(-1),体系适宜初始pH为5.0,污染物初始浓度升高会导致去除效果下降,并且反应体系内乙二胺四乙酸(EDTA)的存在可以提高2,4,6-TCP的去除率.材料的重复利用实验结果表明,经过多次循环反应后会导致材料nZVI核芯的失活和孔道的堵塞.本研究不仅为制备可控壳层厚度的核壳型介孔材料提供了理论指导,而且为进一步改性合成对2,4,6-TP具有高选择性的复合材料提供了依据.展开更多
In order to design and predict the dechlorination processes for remediating the halogenated aromatic com- pounds in the biobarrier system applied in situ, an anaerobic continuous-flow column was set up with the introd...In order to design and predict the dechlorination processes for remediating the halogenated aromatic com- pounds in the biobarrier system applied in situ, an anaerobic continuous-flow column was set up with the introduction of an enriched 2, 4, 6-trichlorophenol （TCP） reductive dechlorinating consortium. The fates of TCP and its metabo- lites were simulated according to the first-order sequential dechlorination kinetic model. The enriched TCP anaerobic dechlorinating consortium dechlorinated 100 p.mol/L TCP to 4-chlorophenol （4-CP） via 2,4-dichlorophenol （DCP） in 10 d. The consortium was predominated with the phylum of Firmicutes and Bacteroidetes, based on the PCR- denaturing gradient gel electrophoresis （DGGE） analysis. After the consortium was applied to the colunm, the ex- perimental data in the steady state were fitted by the least square method, and the first-order dechlorination kinetic constants from TCP to 2,4-DCP, from 2,4-DCP to 4-CP and from 4-CP to phenol, were 1.58 d-1, 2.23 d 1 and 0.206 d-1, respectively. According to the fitting results, the required biobarrier width for the complete remediation of TCP, 2,4- DCP and 4-CP were 126 cm, 130 cm and 689 cm, respectively. The dechlorination/degradation of 4-CP must be in- creased when the technology is applied to the real site.展开更多
基金the Alexander von Humboldt Foundation of Germany, and partly by the CAS and the NNSF of China.
文摘2,4,6-trichlorophenol (TCP) was firstly treated with air ions generated by electric discharge, and high dechlorination (53%) was observed after 60 min treatment, indicating that air ions are an efficient dechlorination means and might have a future in the oxidative removal of chlorinated phenols. In addition, a stepwise degradation of TCP, beginning with the formation of a major product 2,6-dichloro-1,4-benzenediol via substitution, is proposed through a detailed analysis of gas chromatography/mass spectrometry.
基金This work was supported by the China Postdoctoral Science Foundation and the National Natural Science Foundation of China(Grant No.50325824).
文摘The reaction mechanism and pathway of the ozonation of 2,4,6-trichlorophenol(2,4,6-TCP)in aqueous solution were investigated.The removal efficiency and the variation of H_(2)O_(2),Cl^(−),formic acid,and oxalic acid were studied during the semi-batch ozonation experiments(con-tinuous for ozone gas supply,fixed volume of water sample).The results showed that when there was no scavenger,the removal efficiency of 0.1 mmol/L 2,4,6-TCP could reach 99%within 6 min by adding 24 mg/L ozone.The reaction of molecular ozone with 2,4,6-TCP resulted in the formation of H2O2.The maximal concentration of H_(2)O_(2) detected during the ozonation could reach 22.5%of the original concentration of 2,4,6-TCP.The reaction of ozone with H_(2)O_(2) resulted in the generation of a lot of OH·radicals.Therefore,2,4,6-TCP was degraded to formic acid and oxalic acid by ozone and OH·radicals together.With the inhibition of OH·radicals,ozone molecule firstly degraded 2,4,6-TCP to form chlorinated quinone,which was subsequently oxidized to formic acid and oxalic acid.Two reaction pathways of the degradation of 2,4,6-TCP by ozone and O_(3)/OH·were proposed in this study.
基金the National Natural Science Foundation of China(Grant No.21777009)Beijing Natural Science Foundation(Grant No.8182031)Major Science and Technology Program for Water Pollution Control and Treatment(Grant No.2018ZX07109).
文摘Photocatalytic hydrogen production synergized with the oxidation of pollutants is an environmentally friendly and economical approach to generate clean energy and remove the pollution from environment.In this study,photocatalytic hydrogen production cooperating with 2,4,6-trichlorophenol(2,4,6-TCP)degradation have been reinforced by introducing an ultrasonic atomization.The degradation of 2,4,6-TCP in a mist of three photocatalysts(g-C3N4,TiO2,and Bi2O3)generated by ultrasonic atomization was performed under 254 nm ultraviolet(UV254)light irradiation.The results showed that,under UV254 irradiation,three different photocatalysts(g-C3N4,TiO2,and Bi2O3)all accelerated both hydrogen production and 2,4,6-TCP degradation.Additionally,2,4,6-TCP degradation and photocatalytic hydrogen production exhibited an obvious synergistic effect,since 2,4,6-TCP has a strong tendency to react with photo-generated holes and their second radicals so as to inhibit the recombination of carriers,and thus improved the efficiency of hydrogen production simultaneously.Moreover,by introducing ultrasonic atomization,the atomized droplets acted as micro-photocatalytic units to replace the macrophotocatalytic reaction reactor.Therefore,the mass transfer distance for free radicals was restricted and the utilization of light energy by photocatalysts was increased.Further,the reaction efficiency was improved.The results reveal environmentally friendly and economical potential of hydrogen production by photocatalytic degradation of 2,4,6-TCP in atomized droplets.
基金Supported by Grant-in-Aids for Scientific Research from the Ministry of Education,Culture,Sports,Science and Technology of Japan (No.23310055 and No.23658272)
文摘In order to design and predict the dechlorination processes for remediating the halogenated aromatic com- pounds in the biobarrier system applied in situ, an anaerobic continuous-flow column was set up with the introduction of an enriched 2, 4, 6-trichlorophenol （TCP） reductive dechlorinating consortium. The fates of TCP and its metabo- lites were simulated according to the first-order sequential dechlorination kinetic model. The enriched TCP anaerobic dechlorinating consortium dechlorinated 100 p.mol/L TCP to 4-chlorophenol （4-CP） via 2,4-dichlorophenol （DCP） in 10 d. The consortium was predominated with the phylum of Firmicutes and Bacteroidetes, based on the PCR- denaturing gradient gel electrophoresis （DGGE） analysis. After the consortium was applied to the colunm, the ex- perimental data in the steady state were fitted by the least square method, and the first-order dechlorination kinetic constants from TCP to 2,4-DCP, from 2,4-DCP to 4-CP and from 4-CP to phenol, were 1.58 d-1, 2.23 d 1 and 0.206 d-1, respectively. According to the fitting results, the required biobarrier width for the complete remediation of TCP, 2,4- DCP and 4-CP were 126 cm, 130 cm and 689 cm, respectively. The dechlorination/degradation of 4-CP must be in- creased when the technology is applied to the real site.
