果菜秸秆生物炭吸附设施土壤硝态氮性能与机制研究

在农业生产中，过量偏施氮肥导致的硝酸盐富集是次生盐渍化、酸化等土壤障碍的重要诱因。生物炭因良好的吸附特性逐渐成为缓解盐渍化的土壤调理剂，但果菜秸秆生物炭对硝酸盐等离子的吸附研究鲜见报道。以甜椒、番茄和茄子3种果菜秸秆为原料热解制备生物炭，进行硝态氮吸附试验。通过扫描电镜（SEM）和傅里叶近红外光谱（FTIR）等技术对生物炭吸附前、后表面形貌、官能团等进行表征分析，利用吸附动力学模型和等温吸附模型等进行拟合分析，综合模型参数和形貌表征解析果菜秸秆生物炭的吸附性能和机制。研究结果表明，3种果菜秸秆生物炭对硝态氮均具有一定吸附能力，茄子秸秆生物炭吸附能力最强，最大理论平衡吸附量为114.788mg/g，其次为番茄（29.736mg/g）和甜椒（9.759mg/g）；茄子和甜椒秸秆生物炭吸附性能优于玉米、稻壳等大田作物秸秆生物炭，吸附过程符合准二级动力学模型，受化学键吸附、表面吸附和内扩散吸附过程的控制，番茄秸秆生物炭吸附过程符合准一级动力学模型，主要为物理吸附；FTIR分析显示，3种生物炭均含有羟基、甲基、亚甲基、羧基和羰基官能团，除此之外，甜椒和茄子秸秆生物炭还含有醚键，番茄秸秆生物炭含有醇羟基。因此，3种果菜秸秆生物炭对硝态氮均具有吸附能力，茄子秸秆生物炭吸附能力最强，受孔隙填充、官能团和络合作用等多种理化机制的影响，具有消减土壤次生盐渍化的潜力。本研究对盐渍化土壤修复和果菜秸秆资源化利用具有理论意义。

Adsorption of Nitrate Nitrogen by Solanaceous Vegetables Straw-derived Biochar

Nitrogen fertilizer was excessively applied in the agricultural production, which resulted in soil secondary salinization and deterioration. Biochar has been gradually applied in soil restoration due to adsorption capacity. However, solanaceous vegetables straw-derived biochar was rarely reported. The present study aimed to explore the effect of solanaceous vegetables straw-derived biochar on adsorption of nitrate nitrogen and mitigation of soil secondary salinization. Straws of sweet pepper, tomato and eggplant were prepared as biochar by pyrolysis. Adsorption and mechanism for nitrate nitrogen removal by experimental solanaceous vegetables straw biochar was examined. Surface morphology and functional groups were characterized by scanning electron microscopy (SEM) and Fourier transform near-infrared spectroscopy (FTIR). The adsorption process of nitrate nitrogen was simulated and fitted by kinetic model and isothermal adsorption model. The adsorption mechanism of biochar was analyzed according to morphology and model parameters. All of the experimental solanaceous vegetables straw derived biochar showed adsorption capacity of nitrate nitrogen. The maximum adsorption capacity of eggplant, tomato and sweet pepper straw-derived biochar were 114.788mg/g, 29.736mg/g and 9.759mg/g, respectively. The adsorption processes of eggplant and sweet pepper straw biochar were well fitted by quasi-second-order kinetic model, which was controlled by the integrated adsorption of chemical bond, micro-porefilling and internal diffusion. The adsorption process of tomato straw biochar was well fitted by the quasi-first-order kinetic model, which was mainly physical adsorption. Functional groups such as hydroxyl group, methyl group, methylene, carboxyl group and carbonyl group were observed in experimental biochar, according to FTIR analysis. Additionally, ether bonds were observed in eggplant and sweet pepper straw biochar and alcohol hydroxyl groups were observed in tomato straw biochar. Therefore, adsorption capacity of nitrate nitrogen was observed in the experimental solanaceous vegetables straw biochar. The eggplant straw biochar had the greatest adsorption capacity of nitrate nitrogen, which was affected by various physicochemical mechanisms such as pore filling, functional groups and complexation. The results demonstrated that eggplant straw biochar had great potential in amendments of secondary salinization soil. The present study provided insight into the effective utilization of solanaceous vegetables straw and soil remediation in crop production.