Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtse River), Ministry of Agriculture and Rural Affairs, State Environmental Protection Key Laboratory of Soil Health and Green Remediation College of Resources and Environment, Interdisciplinary Sciences Institute, Huazhong Agricultural University, Wuhan, 430070, Hubei Province, China.
Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtse River), Ministry of Agriculture and Rural Affairs, State Environmental Protection Key Laboratory of Soil Health and Green Remediation College of Resources and Environment, Interdisciplinary Sciences Institute, Huazhong Agricultural University, Wuhan, 430070, Hubei Province, China; Hubei Hongshan Laboratory, Wuhan 430070, Hubei Province, China; Shenzhen Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture, Agriculture Genomics Institute at Shenzhen, Chinese Academy of Agriculture Science, Shenzhen, China.
Environ Pollut. 2024 Dec 1;362:125030. doi: 10.1016/j.envpol.2024.125030. Epub 2024 Sep 25.
Biochar is widely used for the remediation of heavy metal-contaminated soils. However, pristine biochar generally has limited active functional groups and adsorption sites, thereby exhibiting low immobilization performance for heavy metals. In addition to carbon (C), silicon (Si) is another common macro-element present in rice husk biochar, but it often exists in the form of amorphous oxide and therefore contributes little to the adsorption performance for heavy metals. The transformation of amorphous Si oxide to dissolved silicate through a precipitation effect can significantly improve its heavy metal immobilization capability. Herein, the amorphous Si oxide in rice husk biochar was activated by sodium hydroxide and then the dissolved silicate was immobilized by calcium salt. The as-synthetized Si-activated biochar was used to remediate cadmium (Cd)-contaminated soils. The results indicated that Si-activated rice husk biochar could reduce Cd migration and environmental risks by the transformation from exchangeable Cd into carbonate-bound and residual Cd. With increasing Ca: Si molar ratio, the content of CaCl and HO-extractable Cd exhibited a decreasing trend. Moreover, a higher addition amount of Si-activated biochar improved the Cd immobilization efficiency. The application of 1.0% Ca/Si molar ratio of 2: 2 Si-activated rice husk biochar decreased the CaCl-Cd and HO-Cd concentration by a maximum of 83.7% and 90.5% compared with pristine rice husk biochar, respectively. The present work proposes an approach for highly efficient remediation of Cd-polluted soils by biochar.
生物炭广泛用于修复重金属污染土壤。然而，原始生物炭通常具有有限的活性官能团和吸附位点，因此对重金属的固定化性能较低。除了碳 (C) 之外，硅 (Si) 是稻壳生物炭中另一种常见的主要元素，但它通常以无定形氧化物的形式存在，因此对重金属的吸附性能贡献不大。通过沉淀作用将无定形硅氧化物转化为溶解的硅酸盐可以显著提高其重金属固定能力。在此，通过氢氧化钠对稻壳生物炭中的无定形硅氧化物进行活化，然后用钙盐固定溶解的硅酸盐。合成的 Si 活化生物炭用于修复镉 (Cd) 污染土壤。结果表明，Si 活化稻壳生物炭可以通过将可交换态 Cd 转化为碳酸盐结合态和残留态 Cd 来减少 Cd 的迁移和环境风险。随着 Ca: Si 摩尔比的增加，CaCl 和 HO 可提取 Cd 的含量呈下降趋势。此外，较高添加量的 Si 活化生物炭提高了 Cd 的固定化效率。与原始稻壳生物炭相比，应用 1.0% Ca/Si 摩尔比为 2:2 的 Si 活化稻壳生物炭可使 CaCl-Cd 和 HO-Cd 浓度分别最大降低 83.7%和 90.5%。本工作提出了一种通过生物炭高效修复 Cd 污染土壤的方法。
