摘要
采用间歇试验考察零价铁去除对氯硝基苯的效果,研究初始pH值、零价铁粒径、零价铁投加量和氧对反应过程的影响。结果表明,在中性和弱酸性条件下零价铁能有效去除对氯硝基苯,反应过程符合准一级动力学,反应终产物为对氯苯胺;降低零价铁粒径和增加零价铁投加量可提高对氯硝基苯的去除率。当零价铁粒径为0.05mm、投加量为0.5 g/L、对氯硝基苯初始质量浓度为25 mg/L,反应6 h后,对氯硝基苯去除率可达100%。氧对零价铁还原对氯硝基苯具有竞争性抑制作用,但零价铁能消耗水中溶解氧并维持对氯硝基苯还原反应进行,与厌氧反应过程相比,空气-水体系对氯硝基苯去除率下降19.18%。研究表明,采用零价铁还原法可有效去除地下水中的对氯硝基苯。
para-chloronitrobenzene （p-CNB） is a toxic contaminant commonly found in ground water. Its existence in ground water threatens the safety of drinking-water source. In this paper, the re- duction of p-CNB by zero-valent iron （ZVI） was investigated with batch tests to assess the feasibility of ZVI for the removal of p-CNB from ground water. The effects of initial pH, iron diameter, iron dosage and oxygen were studied. The results showed that p-CNB could be effectively reduced and the end product of the reaction was para-chloroaniline （p-CAN）. The reaction could be described by using pseudo first-order kinetics. High removal efficiency could be achieved when initial pH value at 7 and below. It is because acidic condition promotes the corrosion of iron, which could produce suffi- cient hydrogen donor from H ~ reduction for the transformation of p- CNB. Moreover, lower pH may eliminate ferrous hydroxide and other protective layers accumulating on the surface of ZVI and generate more fresh active sites. The decrease of iron diameter and the in- crease of iron dosage have enhanced p-CNB removal rate. In this work, fine iron powders possessed higher reaction efficiency for p- CNB removal due to its higher surface area when compared with the bigger iron particles, p-CNB removal rate increased with iron dosage because more active sites were available for the reduction of p-CNB. p-CNB removal rate reached 100% in 6 h when iron diameter, iron dosage and initial p-CNB concentration were 0.05 ram, 0.5 g/L and 25 mg/L, respectively. Oxygen inhibited p-CNB reduction due to its competition with ZVI for electrons. Anyway, ZVI were able to deplete oxygen dissolved in water and maintained p-CNB reduction process. When compared with anaerobic system, p-CNB removal rate of air-water system decreased about 19%. The results in this study indicat- ed that ZVI reduction is an effective way to remove p-CNB from ground water.
出处
《安全与环境学报》
CAS
CSCD
北大核心
2011年第4期64-67,共4页
Journal of Safety and Environment
基金
国家自然科学基金项目(50708039)
国家863项目(2009AA063902)
中央高校基本科研业务费资助项目(2009zm0202)
教育部新教师基金项目(20070561011)
广东省自然科学基金项目(05300188)
关键词
环境工程学
对氯硝基苯
零价铁
还原
environmental engineering
para-chloronitrobenzene
zero-valent iron
reduction
