磁性石化污泥生物炭对土壤镉污染修复研究

A hypoxic pyrolysis process to turn petrochemical sludge into magnetic biochar for cadmium-polluted soil remediation

生物炭普遍被认为是一种很有前途的土壤修复材料,特别是因为它能够通过吸附作用而降低土壤中镉(Cd)的生物有效性。然而,长期修复过程中可能会导致Cd从稳定状态释放出来,这使得生物炭作为Cd吸附剂的回收逐渐得到关注。本研究旨在利用含铁石油污泥一步合成磁性生物炭,研究其对Cd的吸附效率、钝化机理及其在土壤中的应用效果。结果表明,通过缺氧热解可直接将石化污泥废弃物资源化成磁性生物炭(PSMBCs),且PSMBCs在水/土壤中具有良好的回收性能。具体来说,由于其具有表面矿化和阳离子-π配位作用,本研究制备的PSMBCs对Cd的吸附能力为18.4~29.8 mg/g。在水稻泥土中施用1.5%PSMBCs 30 d后,生物有效态Cd含量降低85%,且伴随着土壤pH值和溶解有机质的增加。此外,生物炭浸出液对小麦根系伸长无毒性影响。因此,本研究为石化污泥的资源化处理及其对Cd污染土壤的修复提供了技术参考。

Biochar has been considered as a promising material for soil remediation,particularly for its ability to reduce the bioavailability of cadmium(Cd)in soil through sorption.However,long-term remediation may cause Cd to be released from a fixed state,making the recovery of biochar as an adsorbent for Cd removal an area of increasing interest.The study aims to synthesize biochar with magnetic properties using petroleum sludge containing iron in one-step,and investigate their adsorption efficiency and passivation mechanism for Cd in liquid-solid phase,as well as ecological risks.The results indicate that the petrochemical sludge waste can be directly resourced into magnetic biochar(PSMBCs)using hypoxic pyrolysis,and that it exhibits good recycling performance in water/soil.Specifically,the obtained biochar showed strong sorption capacity for Cd(18.4 to 29.8 mg/g)due to surface mineralization and cation-πcoordination,which played a critical role.After applying 1.5%of PSMBCs for 30 d in paddy soil,the bioavailable content of Cd was decreased by 85.0%.Importantly,the biochar leachates did not have any toxic effects on wheat root elongation.Therefore,this study presents a promising strategy for the benign disposal of petrochemical sludge and their utilization for the remediation of Cd-contaminated soil.