This study reports an investigation into the degradation of 2,4-dichlorophenoxyacetic acid in bubble contactor column by O2/H2O2 process, which is widely used as a principal advanced oxidation process. The degradation...This study reports an investigation into the degradation of 2,4-dichlorophenoxyacetic acid in bubble contactor column by O2/H2O2 process, which is widely used as a principal advanced oxidation process. The degradation of 2,4-dichlorophenoxyacetic acid was studied under different H202/O3 molar ratio and pH value. Meanwhile, TOC removal was investigated both in distilled water and tap water. The influences of ozone transfer and consumed hydrogen peroxide were also discussed. The degradation products and oxidation intermediates were identified by GC-MS and LC-MS. A possible reaction mechanism was thus proposed.展开更多
The degradation of p-nitrotoluene by O3/H2O2 process in a bubble contact column was investigated. Effects of the molar ratio of hydrogen peroxide to ozone,pH value and t-butanol on the oxidation process were discussed...The degradation of p-nitrotoluene by O3/H2O2 process in a bubble contact column was investigated. Effects of the molar ratio of hydrogen peroxide to ozone,pH value and t-butanol on the oxidation process were discussed. It was found that the proper H2O2/O3 molar ratio for the degradation of p-nitrotoluene was around 0.6, different pH values and the presence of t-butanol highly influenced the removal efficiency of p-nitrotoluene. 5-methyl-2-nitrophenol, 2-methyl-5-nitrophenol, (4-nitrophenyl) methanol, 5-(hydroxymethyl)-2-nitro phenol, acetic acid, 2-methylpropane diacid and 2-(hydroxylmethyl)propane diacid were identified as degradation intermediates and products through GC-MS. Radical reaction mechanism and degradation pathway were proposed based on the results of experiments. It is deduced that the benzene ring of p-nitrotoluene can be only destroyed by hydroxyl radicals through a polyhydroxy intermediate pathway. Then unstable polyhydroxy intermediates can be oxidized to different acids with low molecular weight rapidly.展开更多
研究了电催化臭氧过程中,溶液中草酸(OA)在不同条件下的降解效果。结果表明,在电催化臭氧反应体系中,O2在阴极得电子原位生成H2O2与O3反应产生HO·,从而实现难降解污染物的快速去除。电流为50 m A,O3含量越高,OA的去除效果越好;O3...研究了电催化臭氧过程中,溶液中草酸(OA)在不同条件下的降解效果。结果表明,在电催化臭氧反应体系中,O2在阴极得电子原位生成H2O2与O3反应产生HO·,从而实现难降解污染物的快速去除。电流为50 m A,O3含量越高,OA的去除效果越好;O3的质量浓度为75 mg/L,电流高于50 m A时,OA的去除率下降;相对于中性与碱性,酸性条件有利于电催化臭氧过程的进行,对OA的去除有更好的效果;与直接臭氧氧化和电解过程相比,电催化臭氧过程对于OA有较好的去处效果。在O3的质量浓度75 mg/L、电流50 m A的优化条件下,OA在180 min时的去除率达到99%。展开更多
老龄垃圾渗滤液因其成分复杂且可生化性差,故传统技术无法对其进行有效降解,且利用臭氧催化氧化体系处理垃圾渗滤液缺乏系统性评估报道。为解决上述问题,采用臭氧/过二硫酸盐(S2O2^−8,PS)、臭氧/过一硫酸盐(HSO^−5,PMS)和臭氧/过氧化氢(...老龄垃圾渗滤液因其成分复杂且可生化性差,故传统技术无法对其进行有效降解,且利用臭氧催化氧化体系处理垃圾渗滤液缺乏系统性评估报道。为解决上述问题,采用臭氧/过二硫酸盐(S2O2^−8,PS)、臭氧/过一硫酸盐(HSO^−5,PMS)和臭氧/过氧化氢(H2O2)氧化体系,探讨了处理老龄垃圾渗滤液的可行性,考察了初始pH、温度、O3及H2O2、Na2S2O8、KHSO5的投加量等因素对其处理效果的影响,并对其能源效率进行了分析。结果表明,优化条件下,O3/PMS、O3/H2O2和O3/PS的单位数量级能耗(electrical energy per order,EE/O)分别为1007.5、1233.7、662.6 kWh·m^−3,O3/PMS氧化体系处理老龄垃圾渗滤液的效果与O3/H2O2氧化体系相似,且优于O3/PS。由综合处理效果与能耗评估结果可知,O3/H2O2氧化体系最佳,在温度为25℃,pH=6,O3和H2O2投加量分别为3 g·h^−1和2125 mg·L^−1,反应时间为60 min条件下,能耗最低,EE/O降至443.9 kWh·m^−3,且TOC去除率和反应速率常数分别为27.1%和0.0053 min^−1,BOD5/COD也由0.18增至0.26。综合上述结果,基于臭氧体系的高级氧化法能耗较高,可将臭氧催化氧化与低成本的生物处理技术相结合,从而实现对污染物高效经济降解。上述研究结果可为臭氧高级氧化技术的工程化应用提供参考。展开更多
Generation of hydroxyl radicals(·OH)is the basis of advanced oxidation process(AOP).This study investigates the catalytic activity of microporous carbonaceous structure for in-situ generation of·OH radicals....Generation of hydroxyl radicals(·OH)is the basis of advanced oxidation process(AOP).This study investigates the catalytic activity of microporous carbonaceous structure for in-situ generation of·OH radicals.Biochar(BC)was selected as a representative of carbon materials with a graphitic structure.The work aims at assessing the impact of BC structure on the activation of H2O_(2),the reinforcement of the persistent free radicals(PFRs)in BC using heavy metal complexes,and the subsequent AOP.Accordingly,three different biochars(raw,chemically-and physiochemically-activated BCs)were used for adsorption of two metal ions(nickel and lead)and the degradation of phenol(100 mg/L)through AOP.The results demonstrated four outcomes:(1)The structure of carbon material,the identity and the quantity of the metal complexes in the structure play the key roles in the AOP process.(2)the quantity of PFRs on BC significantly increased(by 200%)with structural activation and metal loading.(3)Though the Pb-loaded BC contained a larger quantity of PFRs,Ni-loaded BC exhibited a higher catalytic activity.(4)The degradation efficiency values for phenol by modified biochar in the presence of H2O_(2) was 80.3%,while the removal efficiency was found to be 17%and 22%in the two control tests,with H2O_(2)(no BC)and with BC(no H2O_(2)),respectively.Overall,the work proposes a new approach for dual applications of carbonaceous structures;adsorption of metal ions and treatment of organic contaminants through in-situ chemical oxidation(ISCO).展开更多
基金The National Natural Science Foundation of China (No. 50378028)
文摘This study reports an investigation into the degradation of 2,4-dichlorophenoxyacetic acid in bubble contactor column by O2/H2O2 process, which is widely used as a principal advanced oxidation process. The degradation of 2,4-dichlorophenoxyacetic acid was studied under different H202/O3 molar ratio and pH value. Meanwhile, TOC removal was investigated both in distilled water and tap water. The influences of ozone transfer and consumed hydrogen peroxide were also discussed. The degradation products and oxidation intermediates were identified by GC-MS and LC-MS. A possible reaction mechanism was thus proposed.
基金Sponsored by the National Natural Science Foundation of China(Grant No.50378028)
文摘The degradation of p-nitrotoluene by O3/H2O2 process in a bubble contact column was investigated. Effects of the molar ratio of hydrogen peroxide to ozone,pH value and t-butanol on the oxidation process were discussed. It was found that the proper H2O2/O3 molar ratio for the degradation of p-nitrotoluene was around 0.6, different pH values and the presence of t-butanol highly influenced the removal efficiency of p-nitrotoluene. 5-methyl-2-nitrophenol, 2-methyl-5-nitrophenol, (4-nitrophenyl) methanol, 5-(hydroxymethyl)-2-nitro phenol, acetic acid, 2-methylpropane diacid and 2-(hydroxylmethyl)propane diacid were identified as degradation intermediates and products through GC-MS. Radical reaction mechanism and degradation pathway were proposed based on the results of experiments. It is deduced that the benzene ring of p-nitrotoluene can be only destroyed by hydroxyl radicals through a polyhydroxy intermediate pathway. Then unstable polyhydroxy intermediates can be oxidized to different acids with low molecular weight rapidly.
文摘研究了电催化臭氧过程中,溶液中草酸(OA)在不同条件下的降解效果。结果表明,在电催化臭氧反应体系中,O2在阴极得电子原位生成H2O2与O3反应产生HO·,从而实现难降解污染物的快速去除。电流为50 m A,O3含量越高,OA的去除效果越好;O3的质量浓度为75 mg/L,电流高于50 m A时,OA的去除率下降;相对于中性与碱性,酸性条件有利于电催化臭氧过程的进行,对OA的去除有更好的效果;与直接臭氧氧化和电解过程相比,电催化臭氧过程对于OA有较好的去处效果。在O3的质量浓度75 mg/L、电流50 m A的优化条件下,OA在180 min时的去除率达到99%。
文摘老龄垃圾渗滤液因其成分复杂且可生化性差,故传统技术无法对其进行有效降解,且利用臭氧催化氧化体系处理垃圾渗滤液缺乏系统性评估报道。为解决上述问题,采用臭氧/过二硫酸盐(S2O2^−8,PS)、臭氧/过一硫酸盐(HSO^−5,PMS)和臭氧/过氧化氢(H2O2)氧化体系,探讨了处理老龄垃圾渗滤液的可行性,考察了初始pH、温度、O3及H2O2、Na2S2O8、KHSO5的投加量等因素对其处理效果的影响,并对其能源效率进行了分析。结果表明,优化条件下,O3/PMS、O3/H2O2和O3/PS的单位数量级能耗(electrical energy per order,EE/O)分别为1007.5、1233.7、662.6 kWh·m^−3,O3/PMS氧化体系处理老龄垃圾渗滤液的效果与O3/H2O2氧化体系相似,且优于O3/PS。由综合处理效果与能耗评估结果可知,O3/H2O2氧化体系最佳,在温度为25℃,pH=6,O3和H2O2投加量分别为3 g·h^−1和2125 mg·L^−1,反应时间为60 min条件下,能耗最低,EE/O降至443.9 kWh·m^−3,且TOC去除率和反应速率常数分别为27.1%和0.0053 min^−1,BOD5/COD也由0.18增至0.26。综合上述结果,基于臭氧体系的高级氧化法能耗较高,可将臭氧催化氧化与低成本的生物处理技术相结合,从而实现对污染物高效经济降解。上述研究结果可为臭氧高级氧化技术的工程化应用提供参考。
基金the financial support of the National Science Foundation(NSF EPSCoR RII Grant No.OIA-1632899)。
文摘Generation of hydroxyl radicals(·OH)is the basis of advanced oxidation process(AOP).This study investigates the catalytic activity of microporous carbonaceous structure for in-situ generation of·OH radicals.Biochar(BC)was selected as a representative of carbon materials with a graphitic structure.The work aims at assessing the impact of BC structure on the activation of H2O_(2),the reinforcement of the persistent free radicals(PFRs)in BC using heavy metal complexes,and the subsequent AOP.Accordingly,three different biochars(raw,chemically-and physiochemically-activated BCs)were used for adsorption of two metal ions(nickel and lead)and the degradation of phenol(100 mg/L)through AOP.The results demonstrated four outcomes:(1)The structure of carbon material,the identity and the quantity of the metal complexes in the structure play the key roles in the AOP process.(2)the quantity of PFRs on BC significantly increased(by 200%)with structural activation and metal loading.(3)Though the Pb-loaded BC contained a larger quantity of PFRs,Ni-loaded BC exhibited a higher catalytic activity.(4)The degradation efficiency values for phenol by modified biochar in the presence of H2O_(2) was 80.3%,while the removal efficiency was found to be 17%and 22%in the two control tests,with H2O_(2)(no BC)and with BC(no H2O_(2)),respectively.Overall,the work proposes a new approach for dual applications of carbonaceous structures;adsorption of metal ions and treatment of organic contaminants through in-situ chemical oxidation(ISCO).
