零价铁对土壤中4-氯苯酚还原脱氯研究

氯苯酚是常见的环境污染物，它们在土壤中的加速分解可以减少对人类健康的危害。以恒温培养为方法，GC-MS为检测手段，研究了在常温常压下土壤中4-氯苯酚(4-CP)在零价铁作用下的还原脱氯反应。结果表明：4-CP可以被来自零价铁的电子还原，零价铁能够有效促进土壤中的4-CP脱除苯环上的氯原子，从而达到降低毒性、增加可生化性目的。反应条件如初始pH、时间、零价铁用量等均对4-CP还原脱氯效率有重要影响，特别是当初始pH值控制在偏酸时更有利于反应的进行。在零价铁加入量500mg、初始pH=4、反应时间7d的条件下，零价铁对土壤中4-CP还原脱氯效率最高可以达到65％。利用实验数据，对零价铁作用下4-CP还原脱氯的反应机理也进行了初步探讨。

Zero valent iron dechlorination of 4-chlorophenol in soils

Chlorinated phenols are common organic pollutants of the environment, and their accelerated degradation in soils can alleviate some risk to human health. At ambient temperature and pressure, the natural and the enhanced reductive dechlorination of 4-chlorophenol (4-CP) in soils with zero-valent iron (ZVI) were investigated in the laboratory with isothermal incubation and gas chromatography mass spectrometry (GC-MS) as the primary analytical method. GC-MS analysis indicated that 4-CP in soil was dechlorinated to phenol in the presence of ZVI, effectively decreasing the toxicity of 4-CP. Ultimately, biodegradation of phenol re-sulted in the disappearance of 4-CP in soils. Major factors controlling the reductive dechlorination of 4-CP were tested and evaluated. Experimental data showed that the initial soil pH, the quantity of ZVI, and the reaction time were important factors for the dechlori-nation of 4-CP, and acidic pH was more favorable for the dechlorination reaction to proceed. It was found that 65% of 4-CP in soils could be dechlorinated after 7 days of reaction with 500 mg of ZVI and at an initial pH of 4. Obviously, the addition of ZVI to 4-CP contaminated soils can accelerate the decomposition of this pollutant. In addition, two possible mechanisms of the dechlorination reaction were proposed and discussed.