乳化纳米铁修复硝基苯污染含水层研究

Laboratory evaluation of degradation of nitrobenzene in aquifer using emulsified nanoscale zero-valent iron

通过模拟槽实验,研究了乳化纳米铁原位反应带修复硝基苯污染含水层的有效性以及水文地球化学指标的变化特征.结果表明,在第40d注入井下游大部分区域无硝基苯检出,与之相对应有大量的苯胺生成,这说明注入乳化纳米铁可形成原位反应带对硝基苯进行去除,有效控制硝基苯污染羽;乳化纳米铁的注入导致含水层pH值升高,然而乳化油水解产生的有机酸可与OH-发生中和反应,使pH值得到有效缓冲;Eh降低说明乳化纳米铁注入产生了较强的还原环境,有利于进行硝基苯的降解;pH值的升高与Eh的降低可说明铁还原反应与生物还原反应协同作用降解硝基苯,强化对硝基苯的修复效果;NO_2^-、硫化物的生成说明在模拟槽内发生了NO_3^-还原反应和SO_4^(2-)还原反应.

Simulated experiment was conducted to evaluate the availability of remediation of NB-contaminated aquifer with the emulsified nanoscale zero-valent iron(EZVI)and characteristics of geochemical indicators variations.The results showed that none NB was detected and high concentration of aniline(AN)produced in the downgradient zone of EZVI injected well after40days.These suggested EZVI reaction zone could be formed and remove NB efficiently,and NB-contaminant plume was controlled effectively.EZVI injection could result in increase of pH,however,neutralization reaction of hydroxide ion and organic acid generated by emulsified oil hydrolyzing avoid drastic pH change.Strong reducing environment was form indicated by Eh declination,which was favorable for the degradation of NB.Increase of pH and decrease of Eh implied that EZVI could enhance NB-polluted aquifer remediation by a synergistic effect of iron reduction coupled with biotic processes.Generations of nitrite and sulfide indicated that nitrate reduction and sulfate reduction occurred in the reaction zone.