State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China.
J Environ Sci (China). 2011;23(8):1286-92. doi: 10.1016/s1001-0742(10)60543-8.
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.
零价铁转化多氯联苯（PCBs）是环境修复的最新创新技术之一。研究了纳米零价铁（NZVI）在腐殖酸或金属离子存在下对 4-氯联苯（4-ClBP）的脱氯作用。结果表明，NZVI 对 4-ClBP 的脱氯作用随溶液 pH 值的降低而增加。当初始 pH 值分别为 4.0、5.5、6.8 和 9.0 时，48 小时后 4-ClBP 的脱氯效率分别为 53.8%、47.8%、35.7%和 35.6%。腐殖酸的存在抑制了 4-ClBP 在最初 4 小时内的还原，然后通过在 48 小时内达到 86.3%的脱氯，显著加速了脱氯反应。二价金属离子 Co2+、Cu2+和 Ni2+被还原并与 NZVI 形成双金属，从而增强了 4-ClBP 的脱氯作用。在 0.1mmol/L Co2+、Cu2+和 Ni2+存在下，48 小时时 4-ClBP 的脱氯率分别为 66.1%、66.0%和 64.6%，96 小时时分别增加到 67.9%、71.3%和 73.5%。在所有情况下，NZVI 对 4-ClBP 的脱氯动力学均遵循准一级动力学模型。这些结果为更好地理解实际环境中 PCBs 的脱氯机制提供了依据。
