School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
Department of Electronic Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
Sci Total Environ. 2022 Dec 20;853:158532. doi: 10.1016/j.scitotenv.2022.158532. Epub 2022 Sep 6.
The biochar/persulfate (BC/PS) has been extensively applied in the degradation of organic contaminants in the aqueous solutions. However, much less work has been done on the degradation of organic contaminants in soil by BC/PS, especially on the unclear roles of soil active constituents in the degradation. This study was conducted to investigate the degradation of sulfamethoxazole (SMX) in two soils through PS oxidation activated by biochar. Biochar was produced via the pyrolysis of peanut shell at 400 °C and 700 °C, which was denoted as BC400 and BC700, respectively. Two soils used were red soil and paddy soil, mainly differing in iron minerals and organic matter. Both biochar promoted SMX degradation (42.6 %-90.7 %) in two soils, compared to PS alone (20.9 %-41.7 %). In BC400/PS system, the free radicals were the dominant reactive species for SMX degradation, while the electron transfer pathway played a vital role in the SMX degradation by BC700/PS. Higher SMX degradation was observed in red soil (41.7 %-97.8 %) than that in paddy soil (20.3 %-94.8 %), which was ascribed to the promotion of iron minerals in red soil yet the inhibition of organic matter in paddy soil. Specifically, the reaction between ≡Fe(III)/≡Fe(II) and PS on the surface of iron minerals in red soil generated more SO and OH, resulting in the enhanced SMX degradation. However, the consumption of free radicals and suppression of electron transfer pathway by organic matter in paddy soil inhibited SMX degradation. As the comparative carbonaceous materials to biochar, graphite exerted no obvious degradation effect, whereas activated carbon exhibited the comparable promoting efficacy to BC700. Both biochar, especially BC700, significantly (p < 0.05) alleviated the adverse effects of PS treatment on wheat (Triticum aestivum L.) growth. Overall, this study demonstrates that biochar/persulfate was effective in SMX degradation in soil and the degradation was affected by soil iron minerals and organic matter, which should be paid more attention in the persulfate remediation of organic contaminated soils at a specific site.
生物炭/过硫酸盐（BC/PS）已广泛应用于水溶液中有机污染物的降解。然而，在生物炭/PS 降解土壤中的有机污染物方面，研究工作要少得多，特别是在土壤活性成分在降解中的作用尚不清楚。本研究通过生物炭激活过硫酸盐（PS）氧化，研究了两种土壤中磺胺甲恶唑（SMX）的降解。生物炭是通过在 400°C 和 700°C 下热解花生壳制备的，分别表示为 BC400 和 BC700。所用的两种土壤分别为红壤和水稻土，主要区别在于铁矿物和有机质。与单独的 PS 相比（20.9%-41.7%），两种生物炭都促进了两种土壤中 SMX 的降解（42.6%-90.7%）。在 BC400/PS 体系中，自由基是 SMX 降解的主要反应性物质，而电子转移途径在 BC700/PS 降解 SMX 中起着至关重要的作用。在红壤中观察到更高的 SMX 降解（41.7%-97.8%），而在水稻土中则较低（20.3%-94.8%），这归因于红壤中铁矿物的促进作用，而水稻土中有机质的抑制作用。具体而言，在红壤中铁矿物表面上≡Fe(III)/≡Fe(II)与 PS 之间的反应生成了更多的 SO 和 OH，从而增强了 SMX 的降解。然而，水稻土中有机质对自由基的消耗和对电子转移途径的抑制抑制了 SMX 的降解。作为生物炭的比较碳质材料，石墨没有表现出明显的降解效果，而活性炭表现出与 BC700 相当的促进效果。生物炭，特别是 BC700，显著（p<0.05）减轻了 PS 处理对小麦（Triticum aestivum L.）生长的不利影响。总的来说，本研究表明生物炭/过硫酸盐在土壤中 SMX 的降解是有效的，土壤中铁矿物和有机质会影响降解，在特定地点进行有机污染土壤的过硫酸盐修复时，应更加注意这一点。
