Yunnan Research Academy of Eco-environmental Sciences, Kunming 650034, China.
Department of Environmental Engineering, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China.
J Environ Sci (China). 2022 Mar;113:242-250. doi: 10.1016/j.jes.2021.06.004. Epub 2021 Jun 30.
Oxidation remediation is a commonly used technology for PAHs contaminated soil presently, but the overestimate of efficiency due to ongoing remediation by residual oxidants during extraction and testing has not been paid enough attention. In this study, persulfate was activated by Fe(II) to investigate the effects of residual oxidants on PAHs removal during detection process and the elimination effects of adding NaSO and extending sampling time on residual oxidants. Results verified that the residual oxidants removed PAHs in extraction process, making the results lower than the actual values: the detection recovery rate η of ∑PAHs and 3-6 ring PAHs ranged from 24.3% (25% NaSO treatment) to 87.4% (5% NaSO+4/4Fe treatment), 20.1%-99.0%, 28.9%-87.9%, 20.8%-89.4%, and 18.6%-76.9%, respectively. After adding NaSO, the accuracy of detection results increased significantly: the η of ∑PAHs and 3-6 ring PAHs increased to 64.1%-96.5%, 58.8%-95.5%, 73.8%-114.4%, 60.6%-95.6%, and 45.4%-77.1%, respectively. After 49 days of adding oxidants, residual oxidants had no considerable effect on the detection of PAHs, indicating it was appropriate to start soil remediation verification sampling49 days after the remediation was completed. The observed results will help scientific evaluation of the remediation effects of chemical oxidation on organic contaminated soil.
氧化修复是目前用于多环芳烃污染土壤的常用技术，但由于在提取和测试过程中残留氧化剂的持续修复作用，导致其效率被高估，这一问题尚未得到足够的重视。本研究采用 Fe(II) 活化过硫酸盐，考察了残留氧化剂在检测过程中对 PAHs 去除的影响，以及添加亚硫酸钠和延长采样时间对残留氧化剂的消除效果。结果验证了残留氧化剂在提取过程中去除了 PAHs，导致检测结果低于实际值：∑PAHs 和 3-6 环 PAHs 的检测回收率 η 范围为 24.3%（25%亚硫酸钠处理）至 87.4%（5%亚硫酸钠+4/4Fe 处理）、20.1%-99.0%、28.9%-87.9%、20.8%-89.4%和 18.6%-76.9%，分别。添加亚硫酸钠后，检测结果的准确性显著提高：∑PAHs 和 3-6 环 PAHs 的 η 增加到 64.1%-96.5%、58.8%-95.5%、73.8%-114.4%、60.6%-95.6%和 45.4%-77.1%，分别。添加氧化剂 49 天后，残留氧化剂对 PAHs 的检测没有明显影响，这表明在修复完成后 49 天开始进行土壤修复验证采样是合适的。观察结果将有助于对化学氧化法修复有机污染土壤的修复效果进行科学评价。
