秸秆与土壤矿物的互作动态及其影响Cu离子吸附特性的机制

The immobilization and mobilization of heavy metals in the soil of cultivated land relate closely to the dynamic interactions between crop residue and soil minerals. The organo-mineral complexes which formed by the interactions between organic matter and montmorillonite, kaolinite, goethite, gibbsite, pyrolusite, respectively, during the decomposition of rice straw with the periods of 5, 30, 90, 180 and 360 days are chosen as the research objects in the current project. The physicochemical properties of organo-mineral complexes will be determined, the structural characteristics of organic and inorganic components in organo-mineral complexes will be analyzed. Adsorption behavior of Cu on organo-mineral complexes will be studied by the combined application of equilibrium adsorption, desorption, and isothermal titration microcalorimetry, X-ray Photoelectron Spectroscopy(XPS), Fourier Transform Infrared Spectroscopy(FTIR), Nuclear Magnetic Resonance(NMR) techniques. The effect of the dynamic interactions between rice straw and soil minerals on the adsorption of Cu then can be elucidated. By analyzing the relationship of Cu adsorption behavior with the variation of physicochemical properties and structural characteristics of organo-mineral complexes, the mechanisms of the influence of the dynamic interactions between rice straw and soil minerals on the adsorption of Cu will be clarified.Through this project,the rational evaluation and effective remediation of heavy metal pollution in soil environment will be promoted, the resource utilization of crop residues will also be improved.

秸秆腐解过程中的有机质-土壤矿物动态互作过程与重金属在耕地土壤中的迁移固定紧密相关。本项目选取稻草在腐解5、30、90、180、360天的过程中分别与蒙脱石、高岭石、针铁矿、水铝矿、软锰矿相互作用所形成的有机-无机复合体为研究对象，表征其表面理化性质，分析其有机组分和矿物组分的结构特征，结合平衡吸附、微量热、X射线光电子能谱(XPS)、红外光谱(FTIR)、核磁共振(NMR)等技术手段和吸附态Cu离子的解吸，探讨有机-无机复合体对Cu离子的吸附特性，阐明稻草与土壤矿物的动态互作过程对Cu离子吸附的影响特征。通过分析Cu离子吸附特性变化与有机-无机复合体在稻草腐解过程中的表面理化性质变化和有机、无机组分结构特征变化的关系，阐释稻草与土壤矿物的动态互作过程影响Cu离子吸附特性的潜在机制，为合理评价和有效治理土壤重金属污染、提高秸秆资源利用率提供科学依据。

秸秆腐解过程中有机质与土壤矿物的动态互作过程与重金属在耕地土壤中的迁移固定紧密相关。本项目选取秸秆和土壤中典型的矿物为研究材料，进行腐解和复合的动态模拟实验。通过分析有机-无机复合体的表面理化性质、有机无机结构及Cu离子吸附特征变化，探讨秸秆与土壤矿物的互作动态及其影响Cu离子吸附特性的潜在机制。取得的主要结果如下：1. 有机质-蒙脱石复合体的比表面积和平均孔径在腐解过程中呈减小趋势，有机质-高岭石复合体、有机质-赤铁矿复合体、有机质-三水铝石复合体的比表面积在腐解过程中大致呈增大趋势，而平均孔径大致呈减小趋势。2. 秸秆在腐解过程中与蒙脱石的复合减少了负电荷量和潜在吸附点位，与高岭石、铁、铝氧化物的复合使正电荷减少、负电荷增多，潜在吸附点位增加。3. 各复合体中有机碳以烷氧碳结构为主体，芳香碳和羰基碳含量均较低，各复合体系中有机碳的芳香化程度和腐殖化程度在腐解过程中多增强。4. 有机质-蒙脱石复合体中蒙脱石的结构在腐解过程中有一定程度的改变，其它复合体中矿物结构的变化较小。5. 秸秆在腐解过程中与蒙脱石的复合降低了对Cu离子的初始吸附速率、吸附过程中的速率和最大吸附量，与高岭石、铁、铝氧化物的复合增大了对Cu离子的初始吸附速率和最大吸附量，降低了吸附过程中的速率。6. 各有机无机复合体对Cu离子的吸附均为自发、吸热、熵增过程。7. Cu主要以正二价形式被有机无机复合体吸附，通过形成化学键的专性吸附机制在复合体表面的作用低于纯矿物表面，氨基、羟基和羧基参与了吸附过程。8. 有机质-三水铝石复合体对Cu离子吸附容量与其潜在吸附位点呈显著正相关，有机质-赤铁矿复合体对Cu离子吸附容量与其比表面积呈显著正相关，有机质-蒙脱石复合体对Cu离子吸附容量与其潜在吸附位点和比表面积均呈显著正相关，有机质的腐殖化和芳香化是促进有机质-高岭石复合体、有机质-赤铁矿复合体、有机质-三水铝石复合体对Cu离子吸附的重要原因。