红壤可变电荷矿物的酸碱缓冲能力及表面络合模型

发布时间：2018-04-02 05:27

本文选题：氧化铁　切入点：高岭石　出处：《化学学报》2017年06期

【摘要】：氧化铁和高岭石是红壤中可变电荷的主要来源,对红壤的酸碱变化起到缓冲作用.本研究基于红壤矿物的表征和酸碱滴定实验结果,采用1-site/2-pK表面络合模型获得了其表面活性位点浓度Hs、密度Ds、酸碱平衡常数pK_a~(int)以及电荷零点pH_(pzc)等相关参数,定量解析了氧化铁和高岭土的酸碱缓冲能力.结果表明:该模型能较好地适用于分析针铁矿、赤铁矿及高岭石的表面酸碱性质;针铁矿、高岭石表面活性位点浓度Hs较高,说明其对酸具有较好的缓冲效果.根据上述酸碱性质参数,模拟计算了不同pH下的矿物表面化学物种,揭示了矿物表面反应缓冲土壤酸碱变化的机制.采用上述酸碱滴定方法及模型计算方法,分析实际林地红壤样品的酸碱缓冲能力,并采用表面络合模型计算了其表面化学物种,验证了该方法用于林地红壤酸碱缓冲能力分析的可行性.
[Abstract]:Iron oxide and kaolinite are the main sources of variable charge in red soil.Based on the characterization of red soil minerals and the results of acid-base titration experiments, the surface active site concentration (HS), density (DS), acid-base equilibrium constant (pKAZC) and charge zero pH value (PZC) were obtained by 1-site/2-pK surface complexation model.The acid-base buffering capacity of iron oxide and kaolin was quantitatively analyzed.The results show that the model can be used to analyze the surface acid-base properties of goethite, hematite and kaolinite, and the concentration of surface active site H _ s of goethite and kaolinite is high, which indicates that the model has a better buffer effect on acid.According to the above acid-base property parameters, the surface chemical species of minerals at different pH were simulated and calculated, and the mechanism of mineral surface reaction buffer soil acid-base variation was revealed.The acid-base titration method and the model calculation method were used to analyze the acid-base buffer capacity of the red soil samples of the actual woodland, and the surface chemical species were calculated by the surface complexation model.The feasibility of applying this method to the analysis of acid-alkali buffer capacity of forest red soil was verified.
【作者单位】：贵州师范大学化学与材料科学学院;广东省生态环境技术研究所广东省农业环境综合治理重点实验室;
【基金】：科技部红壤酸化973项目(2014CB441002) 国家自然科学基金委中英国际合作红壤关键带项目(41571130052)资助~~
【分类号】：O655.2;S153

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