土壤学报2011，Vol.48Issue(2)：320-330,11.
针铁矿-高岭石二元体的微观结构与形成机制
MICROSTRUCTURE OF GOETHITE-KAOLINITE DYAD AND MECHANISM OF ITS FORMATION
摘要
Abstract
Comparison of lab-prepared goethite-kaolinite association with goethite-kaolinite mixture as control was done for analysis of its microstructure and mechanism of its formation. It was found that in the association kaolinite was well wrapped by goethite, but in the mixture they coated neither. Compared to pure goethite or kaolinite, neither goethite or kaolinite in the association showed much change in the distance between major crystal planes; but the association showed a higher micropore volume and a lower average pore diameter. However, both pore parameters of the mixture were close to the average values of monomeric goethite and kaolinite. The surface fractal dimension D of the mixture and the association increased, and Dmixture was higher than Dassoeiation. Infrared spectra (IR) demonstrated that the vibration frequency of ≡Fe-OH increased and that of ≡ Al-OH, Al-O, Si-0 and Fe-O decreased in the dyads. The magic angle spinning nuclear magnetic resonance spectroscopy (MAS NMR) showed that the cementation between goethite and kaolinite led to increased chemical shift of 29Si and 27Al towards positivity, which implied that cation exchange between ≡Fea OH2(m/2)+(n=1,2,3) and ≡Si-OH or ≡Al-OH20.5+, and anion exchange between ≡Fe-OH and ≡Si-O- or ≡Al-OH0.5-,surface coordination between O atoms on the surface of kaolinite and Fe atoms on the surface of goethite were the main mechanisms of cementation between goethite and kaolinite, where hydrogen bond and electrostatic attraction served as the main acting forces. Although the IR and NMR parameters of the association and mixture displayed similar changes, the variation of the former was more significant, indicating that the cementation strength between goethite and kaolinite in the association is greater than in the mixture.关键词
针铁矿/高岭石/复合物/微观结构/交互作用Key words
Goethite/ Kaolinite/ Association/ Microstructure/ Interaction分类
农业科技引用本文复制引用
魏世勇,刘凡,冯雄汉,谭文峰..针铁矿-高岭石二元体的微观结构与形成机制[J].土壤学报,2011,48(2):320-330,11.基金项目
国家自然科学基金项目(40671088,40471071)和教育部新世纪优秀人才支持计划项目(NCET-08-0781)资助 （40671088,40471071）
