土壤中典型矿物质对生物炭吸附除草剂的影响

发布时间：2018-04-01 05:26

本文选题：生物炭　切入点：除草剂　出处：《绍兴文理学院》2017年硕士论文

【摘要】：生物炭作为土壤改良材料施用于土壤后将影响除草剂的吸附。同时,土壤中的矿物质如蒙脱石、氧化铝、高岭土等对除草剂也具有一定的吸附性能,它们与生物炭在吸附除草剂上的选择性、竞争行为以及相互影响有待研究。本文首先以木屑、稻草、牛粪等为原料制备生物炭。样品分析结果表明,随着热解温度升高,生物炭的芳香性提高、极性降低,比表面积增加。与氮气氛下中制备的生物炭比较,在马弗炉中限氧热解得到的生物炭比表面积更大,可达430 m2/g。等温吸附实验结果表明,矿物质中蒙脱石、氧化铝对除草剂的吸附能力较好。氮气氛下制备的生物炭比表面积较小,对除草剂的吸附以分配作用为主,除草剂的疏水性越高越有利于吸附。马弗炉中限氧热解得到的两种木屑炭(MWS400、MWS600)对嗪草酮和乙草胺的平衡吸附量明显超过其它生物炭。采用扫描电镜和能谱(SEM-EDS)联用探讨了除草剂在矿物质/生物炭复合物表面的吸附分布情况,结果表明,复合物表面吸附的除草剂主要集中于矿物质表面。利用元素分析(EA)估算复合物中生物炭对吸附除草剂的贡献,结果表明,在氧化铝/生物炭复合物中,生物炭对吸附除草剂的贡献率大多超过50%,其中对吸附莠去津的贡献率更高。说明在复合物中生物炭对除草剂的吸附主要位于生物炭内部孔结构中。分别探讨了矿物质处理对生物炭孔结构和吸附性能的影响。结果表明,经过氧化铝和蒙脱石处理后生物炭的比表面积、孔径和介孔容增大。生物炭MWS400经过氧化铝处理后微孔比表面积SAmicro增加了2.44倍、介孔比表面积SA17-500?增加了2.06倍;MWS600经过氧化铝处理后SAmicro变化不显著、SA17-500?增加了1.94倍。通过提取MWS400中的未碳化有机质、并经元素分析(EA)、红外光谱(IR)和核磁共振波谱(NMR)分析表明,氧化铝对生物炭的扩孔作用与它对生物炭孔隙中高含氧有机质的转移有关。经过氧化铝处理后生物炭对除草剂的平衡吸附量提高,通过吸附模型拟合发现生物炭对除草剂的吸附来自于分配和孔隙填充的共同贡献。基于除草剂分子尺寸的模拟计算,发现生物炭中的介孔对于吸附除草剂起了主导作用。
[Abstract]:The application of biochar as a soil improvement material will affect the adsorption of herbicides. At the same time, minerals in soil such as montmorillonite, alumina and kaolinite also have some adsorption properties on herbicides, such as montmorillonite, alumina and kaolinite. The selectivity, competitive behavior and interaction between biochar and biochar on adsorption herbicide need to be studied. In this paper, we first prepared biochar from sawdust, straw and cow dung. The results of sample analysis show that the pyrolysis temperature increases with the increase of pyrolysis temperature. Compared with those prepared in nitrogen atmosphere, the specific surface area of biochar obtained by oxygen-limiting pyrolysis in muffle furnace is much larger, reaching 430 m2 / g. The isothermal adsorption results show that the specific surface area of biochar is higher than that of biochar prepared in nitrogen atmosphere, and the specific surface area of biochar is higher than that of biochar prepared in nitrogen atmosphere, which can reach 430 m2 / g. The adsorption ability of montmorillonite and alumina on herbicide is better. The specific surface area of biochar prepared in nitrogen atmosphere is small, and the adsorption of herbicide is mainly distributed. The higher the hydrophobicity of herbicide is, the more favorable the adsorption is. The equilibrium adsorption capacity of two kinds of wood scraps, MWS400 and MWS600, obtained from Oxygen-limited pyrolysis in muffle furnace is obviously higher than that of other biochar. A study on the combination of SEM and EDS SEM-EDS. The adsorption distribution of herbicide on the surface of mineral / biochar complex was discussed. The results showed that the herbicide adsorbed on the surface of the complex was mainly concentrated on the mineral surface. The contribution of biochar to the adsorption of herbicide was estimated by elemental analysis EAA. The results showed that in the alumina / biochar complex, The contribution rate of biochar to adsorption herbicide is more than 50%, and the contribution rate to adsorption of atrazine is higher than that of biochar. It shows that the adsorption of herbicide by biochar in complex is mainly located in the pore structure of biochar. Effects of substance treatment on pore structure and adsorption properties of biochar. After the treatment of alumina and montmorillonite, the specific surface area, pore size and mesoporous volume of biochar MWS400 increased by 2.44 times, and the mesoporous specific surface area SA17-500? The SAmicro of MWS600 was increased by 2.06 times after alumina treatment, and the change of SAmicro was not significant (SA17-500). The content of uncarbonated organic matter in MWS400 was extracted and analyzed by elemental analysis, IR and NMRs. The pore expansion effect of alumina on biochar is related to the transfer of organic matter with high oxygen content in biochar pores. After alumina treatment, the equilibrium adsorption of herbicide on biochar is increased. It was found that the adsorption of herbicides by biochar came from the contribution of distribution and pore filling. Based on the simulation of the molecular size of herbicides, it was found that mesoporous in biochar played a leading role in the adsorption of herbicides.
【学位授予单位】：绍兴文理学院
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ424;O647.3

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