摘要
针对因地下水中低氯代芳香族有机物碳氯键键能高,零价铁技术对其还原能力不足的问题,制备纳米Fe/Cu双金属颗粒,并引入维生素B_(12),构建Fe/Cu-B_(12)催化还原体系,旨在通过添加零价铜和维生素B_(12)强化零价铁的还原能力,选用2,4-二氯苯酚作为低氯代芳香族有机物的代表物,主要用反应动力学方法考察Fe/Cu-B_(12)体系对2,4-二氯苯酚的催化还原能力,研究了铜负载率、pH等因素对Fe/Cu-B_(12)体系还原能力的影响,最后对Fe/Cu-B_(12)体系降解低氯代芳香族有机物的还原机理做了初步探讨.结果表明:(1)Fe/Cu-B_(12)体系对2,4-二氯苯酚的还原速率常数和脱氯率分别是0.303 6 h-1和70.12%,远大于Fe体系的还原速率常数0.025 7 h-1和脱氯率5.95%,并且大于Fe/Cu体系和Fe-B_(12)体系的还原速率常数之和及脱氯率之和.(2)当铜负载率小于10%时,Fe/Cu-B_(12)体系的反应速率随铜负载率的增大而增大,当铜负载率大于10%时,反应速率随铜负载率的增大而减小.(3)过酸和过碱的pH环境都会弱化体系的还原性能,pH=9.5的弱碱性环境还原性能最优.(4)零价铜与维生素B_(12)在体系中具有协同作用,维生素B_(12)被零价铁还原后与氢氧根络合成强亲核试剂羟维生素B_(12),在零价铜表面的催化下对2,4-二氯苯酚进行高效还原.研究显示,Fe/Cu-B_(12)体系对2,4-二氯苯酚具有高效脱氯能力,铜负载率和pH值是影响体系还原能力的重要因素,零价铜与维生素B_(12)的协同作用是Fe/Cu-B_(12)体系具有高效催化还原能力的重要原因.
To improve the insufficient reducing power of zero-valent iron when degrading the low-chlorinated aromatic organics in groundwater,bimetallic Fe/Cu nanoparticles were prepared with the introduction of vitamin B12 to constitute Fe/Cu-B12 catalytic reduction system and to enhance the reducing capacity of zero-valent iron by adding zero-valent copper and vitamin B12.2,4-dichlorophenol was selected as a representative among the low-chlorinated aromatic organics.The reducing capacity of Fe/Cu-B12 system was investigated by the reaction kinetics method.The effects of copper loading rate and pH on the reduction ability of Fe/Cu-B12 system were also investigated.Finally,the mechanism of Fe/Cu-B12 system catalytically reducing low-chlorinated aromatic organics was discussed.The results show that:①the reduction rate constant and dechlorination rate of 2,4-dichlorophenol in Fe/Cu-B12 system were 0.3036 h-1 and 70.12%,respectively,which were much larger than the reduction rate constant(0.0257 h-1)and chlorine rate(5.95%)of Fe system.Furthermore,the reduction rate constant of Fe/Cu-B12 system was also larger than the sum of the reduction rate constants of the Fe/Cu system and the Fe-B12 system,as well as the dechlorination rate.②When the copper loading rate was less than 10%,the reaction rate of the Fe/Cu-B12 system was increasing along with the increase of copper loading.The opposite phenomenon was found when the copper loading rate was greater than 10%.③Overly basic or acidic environment would weaken the reduction capacity of the system.The optimal pH was found to be 9.5.④An obvious synergistic effect was noticed in Fe/Cu-B12 system during the degradation reaction.Vitamin B12 was reduced by zero-valent iron complexes with the hydroxide to form a strong nucleophile hydroxyvitamin B12,2,4-dichlorophenol was reduced by hydroxyvitamin B12 under the catalysis of zero-valent copper.This study showed that Fe/Cu-B12 system had high dechlorination capacity for 2,4-dichlorophenol,and copper loading rate and pH value were impo
作者
毕越
邱春生
张婷婷
潘煜
孙力平
BI Yue;QIU Chunsheng;ZHANG Tingting;PAN Yu;SUN Liping(School of Environmental and Municipal Engineering,TCU,Tianjin 300384,China)
出处
《天津城建大学学报》
CAS
2021年第1期45-53,共9页
Journal of Tianjin Chengjian University
基金
国家自然科学基金(51478292)。
