Department of Civil and Environmental Engineering, Pusan National University, 2, Busandaehak-ro 63beon-gil, Geumjeong-gu, Busan, 46241, Republic of Korea.
National Institute of Chemical Safety, Hazard Management Division, Hwangyeong-ro 42, Seo-gu, Incheon, 404-708, Republic of Korea.
Chemosphere. 2024 Oct;366:143440. doi: 10.1016/j.chemosphere.2024.143440. Epub 2024 Oct 5.
Soil contamination with hazardous substances like phenol poses significant environmental and health risks. In situ soil mixing can be a promising technological solution to this challenge. A persulfate and sulfidated zero-valent iron (S-ZVI) system for remediating contaminated soil was developed and tested to be suited to in situ soil mixing. S-ZVI was synthesized using a ball mill process, and the optimal sulfur to iron molar ratio for effectively removing phenol from soil removal without pyrophoric risks was 0.12. Soil slurry experiments were performed, and the best phenol oxidation results (high stoichiometric efficiency and sustained oxidation after mixing) were achieved at a persulfate to S-ZVI molar ratio of 2:1 and a persulfate to phenol molar ratio of 8:1. A high organic matter content of the silty clay fraction of the soil strongly suppressed persulfate activation, so suppressed phenol removal and increased persulfate consumption. Electron spin resonance and radical scavenging tests confirmed that hydroxyl and sulfate radicals were present during the degradation of phenol. While sulfate radicals predominantly facilitated degradation in the soil, both sulfate and hydroxyl radicals were crucial in the aqueous phase in the absence of soil organic matter. In situ soil mixing simulation tests indicated that the persulfate and S-ZVI doses and the mixing rate and duration strongly affected the efficacy of the system, and the optimal conditions for phenol removal were determined. The results indicated that the persulfate/S-ZVI system could be tuned to achieve sustained persulfate activation and to remediate contaminated soil employing in situ soil mixing technique.
土壤受到酚等有害物质的污染会带来严重的环境和健康风险。原位土壤混合可以成为解决这一挑战的一种有前途的技术方案。本研究开发了一种过硫酸盐-硫化零价铁（S-ZVI）体系来修复污染土壤，并对其在原位土壤混合中的适用性进行了测试。S-ZVI 是通过球磨工艺合成的，从土壤中有效去除酚而无自燃风险的最佳硫铁摩尔比为 0.12。进行了土壤泥浆实验，在过硫酸盐与 S-ZVI 的摩尔比为 2:1 且过硫酸盐与酚的摩尔比为 8:1 的条件下，实现了最佳的苯酚氧化效果（高化学计量效率和混合后持续氧化）。土壤粉质粘粒部分的高有机质含量强烈抑制了过硫酸盐的活化，因此抑制了苯酚的去除并增加了过硫酸盐的消耗。电子顺磁共振和自由基清除试验证实，在苯酚降解过程中存在羟基和硫酸根自由基。虽然硫酸根自由基主要促进了土壤中的降解，但在没有土壤有机质的情况下，硫酸根和羟基自由基在水相都至关重要。原位土壤混合模拟实验表明，过硫酸盐和 S-ZVI 的剂量、混合速率和持续时间强烈影响了该系统的效果，并确定了去除苯酚的最佳条件。结果表明，过硫酸盐/S-ZVI 体系可以通过调整来实现持续的过硫酸盐活化，并采用原位土壤混合技术来修复污染土壤。
