摘要
利用改性纳米Fe/Ni双金属还原降解2,4-二氯酚(2,4-DCP),考察了p H对Fe/Ni还原降解2,4-DCP的效率的影响。结果表明:当p H=5.5,反应时间为120 h时,由于吸附及还原2种作用,Fe/Ni对水中2,4-DCP的去除率接近100%,且47.0%的2,4-DCP被脱氯还原为苯酚。p H<5.5时,Fe0被腐蚀消耗较多,且H+会与2,4-DCP争夺电子,不利于还原反应的进行;p H>5.5时,因参与脱氯还原的H+不足及铁氢氧化物沉淀覆盖活性位点,导致还原降解效率随着p H升高而降低。通过分析中间产物和最终产物的浓度变化,明确了2,4-DCP的还原降解途径:(1)2,4-DCP被Fe/Ni还原脱去一个氯生成2-氯酚或4-氯酚,然后继续脱氯生成苯酚;(2)2,4-DCP直接被脱去2个氯生成苯酚。
Effects of pH on the dechlorination of 2, 4-dichlorophenol （2, 4-DCP） by nanoscale Fe/Ni was investigated. It was found that when pH was 5.5 and reaction time was 120 h, the removal rate of 2, 4-DCP due to adsorption and reduction was nearly 100%, and 47.0% of 2, 4-DCP was degraded to phenol. When pH value was lower than 5.5, the increasing corrosion of Fe^0 and the competition of H^＋ with 2, 4-DCP would adversely affect the reduction of 2, 4-DCP. When pH〉5.5, the amount of H^＋ was insufficient and the precipitation of ferrous hydroxide could block the reactive sites on the surface of Fe^＋0, resulting in the decrease of reduction efficiency with the increase of pH. The degradation pathway of 2, 4- DCP was confirmed according to the analysis of intermediate and end products, that is, 2,4-DCP was dechlorinated a chlorine atom to produce 2-chlorophenol and 4-chlorophenol at first, and then the dechlorination was performed sequentially to form phenol. 2, 4-DCP was dechlorinated two chlorine atoms simultaneously to generate phenol.
出处
《环境科学与技术》
CAS
CSCD
北大核心
2015年第6期151-155,共5页
Environmental Science & Technology
基金
湖北省自然科学基金项目(2014CFB821)
