磁性生物炭材料降解土壤中残留农药的实验研究

Experimental Study on Degradation of Pesticide Residues in Soil by Magnetic Biochar Material

以玉米秸秆为原料、Fe(NO_(3))_(3)为改性材料,制备了磁性多孔生物炭。以磁性生物炭为催化剂、过硫酸钾为氧化剂,分析催化剂或氧化剂的添加及其施用量对降解土壤中常见农药氧化乐果的作用效果。实验结果如下:加入KHCO_(3)促进普通生物炭C400产生丰富的孔隙,显著增大比表面积;负载铁盐后,多孔生物炭C800的比表面积和孔体积明显增大,生物炭由无定形碳结构转化为石墨化碳结构,具有了更好的磁化强度和吸附性能;铁纳米颗粒负载量越高,生物炭石墨化程度越强。添加磁性生物炭材料能够显著提高土壤中氧化乐果去除效率;磁性生物炭材料中铁含量的增加和石墨化程度的增大提高了土壤中氧化乐果的去除效率。此外,增加催化剂和氧化剂的施用量均能进一步提高土壤中氧化乐果的去除效率;相比于增加氧化剂的施用量,催化剂施用量的增加对提高土壤中氧化乐果的去除效率更加明显。铁改性生物炭对土壤中残留农药具有良好的去除能力,可为农药污染土壤的修复治理提供新的思路。

Corn stover was taken as the raw material and Fe(NO_(3))_(3) as the modified material for the preparation of magnetic porous biochar.Magnetic biochar was used as catalyst and potassium persulfate as oxidant,the effects of catalyst or oxidant supply and application amount on degradation of dimethoate oxide,a common pesticide in soil was assayed.The experimental results showed that the formation of abundant pores in ordinary biochar C400 was promoted by adding KHCO_(3),which significantly increased the specific surface area.Addition of iron salts significantly increased the specific surface area and pore volume of porous biochar C800,and the structure of biochar transformed from amorphous carbon structure to graphitized carbon structure,with better magnetization and adsorption properties.The higher the load of iron nanoparticles,the stronger the graphitization degree of biochar.The addition of magnetic biochar material could significantly improve the removal efficiency of omethoate in soil.With the increment of iron content and graphitization degree of magnetic biochar material,the removal efficiency of omethoate in contaminated soil was enhanced.In addition,increasing the application amount of catalyst or oxidant could further improve the removal efficiency of omethoate in contaminated soil.Compared to oxidant,increasing the application amount of catalyst had higher removal efficiency of omethoate in contaminated soil.Iron-modified biochar had a good ability to remove pesticide residues in soil,it could provide a new idea for the remediation of contaminated soil.