title: Humic acid and metal ions accelerating the dechlorination of 4-chlorobiphenyl by nanoscale zero-valent iron.
abstract: Transformation of polychlorinated biphenyls (PCBs) by zero-valent iron represents one of the latest innovative technologies for environmental remediation. The dechlorination of 4-chlorobiphenyl (4-ClBP) by nanoscale zero-valent iron (NZVI) in the presence of humic acid or metal ions was investigated. The results showed that the dechlorination of 4-ClBP by NZVI increased with decreased solution pH. When the initial pH value was 4.0, 5.5, 6.8, and 9.0, the dechlorination efficiencies of 4-ClBP after 48 hr were 53.8%, 47.8%, 35.7%, and 35.6%, respectively. The presence of humic acid inhibited the reduction of 4-ClBP in the first 4 hr, and then significantly accelerated the dechlorination by reaching 86.3% in 48 hr. Divalent metal ions, Co2+, Cu2+, and Ni2+, were reduced and formed bimetals with NZVI, thereby enhanced the dechlorination of 4-ClBP. The dechlorination percentages of 4-ClBP in the presence of 0.1 mmol/L Co2+, Cu2+ and Ni2+ were 66.1%, 66.0% and 64.6% in 48 hr, and then increased to 67.9%, 71.3% and 73.5%, after 96 hr respectively. The dechlorination kinetics of 4-ClBP by the NZVI in all cases followed pseudo-first order model. The results provide a basis for better understanding of the dechlorination mechanisms of PCBs in real environment.
authors: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China. wangyu@issas.ac.cn
authors: Yu
authors: Y
authors: Wang
authors: Dongmei
authors: D
authors: Zhou
authors: Yujun
authors: Y
authors: Wang
authors: Xiangdong
authors: X
authors: Zhu
authors: Shengyang
authors: S
authors: Jin
mesh_terms: D001713:Biphenyl Compounds / Q000737:chemistry*; D006812:Humic Substances; D007501:Iron / Q000737:chemistry*; D008670:Metals / Q000737:chemistry*
chemical_list: D001713:Biphenyl Compounds; D006812:Humic Substances; D008670:Metals; D007501:Iron; C006983:4-chlorobiphenyl