原质及改性生物炭对土壤重金属污染物影响的研究进展

Research progress on the effects of raw and modified biochar on soil heavy metal pollutants

土壤重金属污染问题日益突出,已经对土壤生态环境造成严重危害。生物炭材料来源广泛、成本较低,在环境污染治理中应用较多,已成为当前环境污染功能材料中的研究热点。笔者介绍制备生物炭所需的生物质来源和制备技术,以及生物质原料和制备温度对生物炭性质的影响;讨论生物炭对重金属的吸附机理,并探析生物炭对土壤重金属污染物的修复效果;总结生物炭的改性方法以及改性后结构变化,阐述改性生物炭的性能提升和对重金属的修复效果。目前多数研究旨在探究生物炭对土壤中重金属污染物的修复效果和作用机制,但对生物炭的最终去向、循环利用和对土壤环境的负面影响等方面缺乏研究,未来的研究趋势应该着重于完善生物炭的选取标准和制备体系,避免生物炭对土壤环境造成二次污染。

[Background]Duo to the rapid development of modern society,soil heavy metal pollution becomes increasingly prominent,which seriously threatens the security of ecological environment.Biochar comes from a wide range of biological sources and of a low cost.It has a huge specific surface area,complex pore structure and abundant functional groups.With its excellent performance,it can effectively renovate soil heavy metal pollution,making it a research hotspot in a variety of environmental functional materials.With the complexity of soil heavy metal pollution types,it is necessary to modify biochar to achieve the purpose of improving the remediation effect.[Methods]In view of this research hotspot,numerous literature retrieval were carried out with“biochar”,“soil heavy metal pollution”,“passivation remediation”and“modified biochar”as keywords.These keywords appeared very frequently in relevant fields.Representative literatures were selected for analysis and integration.The characteristic and applications of biochar were briefly described,the remediation effects of biochar on heavy metal pollutants were summarized,and the modified biochar was emphatically discussed,and the properties of modified biochar and the changes of its effects on heavy metals were discussed.[Results]Biochar comes from a wide range of sources(agricultural wastes,sludge,fruit shells,and poultry dung),it is mainly prepared by low-temperature anoxic slow-speed pyrolysis technology.Its properties mainly depend on the types of biomass raw materials and pyrolysis conditions.The adsorption mechanism of biochar for heavy metals can be divided into surface adsorption(physical adsorption),surface complexation or precipitation,ion exchange and electrostatic attraction,which can effectively reduce the availability and migration of heavy metal pollutants in soil.After modification,the application performance of biochar is enhanced,for example,functional groups are introduced,impurities are removed and surface performance is improved.Remediation effect of heavy metal pollutants in soil is significantly improved.[Conculsions]The treatment of heavy metal contaminated soil by modified biochar has been quite effective,but at present,it is mainly in the laboratory stage or small-scale test stage,and there is a lack of large-scale in-situ experiments.The aging and final flow direction of biochar are not studied deeply enough.The selection of raw materials of biochar should follow the principle of taking local materials,and the secondary pollution of soil environment should be avoided in the process of treatment.Green environmental protection and efficiency is the development trend of biochar field.