【目的】研究不同含钾矿物中钾的释放及动力学,为土壤钾素肥力的合理评价及土壤钾的高效利用提供理论依据。【方法】以常见含钾矿物(黑云母、白云母、正长石、微斜长石)为材料,采用低分子量有机酸(草酸、酒石酸)和无机酸(硝酸)连续浸提的方法,研究钾素释放规律及动力学。【结果】与水(对照)相比,酒石酸,草酸和硝酸累积提取黑云母钾量显著增加了2.7倍、4.1倍、22.3倍;提取白云母的钾量显著增加了61.2%、106.5%和226.8%;提取正长石的钾量显著增加了39.0%、87.6%和154.6%;提取微斜长石的钾量显著增加了44.5%、88.9%和158.7%。分别用一级动力学模型、双常数模型、扩散模型、Elovich模型对不同含钾矿物的累积释钾量进行拟合,动力学方程的相关系数为0.708—1.000(r0.01=0.549),均显著相关。【结论】各浸提剂均能显著提高钾的释放量;含钾矿物不同,钾的累积释放量差异显著,表现为黑云母〉白云母〉微斜长石“正长石。黑云母、正长石、微斜长石的最优模型是双常数模型,白云母的最优模型是Elovich模型。
[Objective] Potassium release and kinetics of different K-bearing minerals were studied to provide scientific evidence for reasonable evaluation of K fertility and high efficient utilization of soil potassium. [Method] Different K-beating minerals (biotite, muscovite, orthoclase and microcline) were extracted successively with low-molecular weight organic acids (oxalic acid, tartaric acid) and inorganic acids (HNO3) to study potassium release and kinetics. [Result] The results showed that the amount of K from biotite extracted successively by oxalic acid, tartaric acid and HNO3 by increased significantly 2.7 times, 4.1 times and 22.3 times compared to that of by water, respectively. The release amount of K from muscovite increased by 61.2%, 106.5% and 226.8%, respectively. The release amount of K from orthoclase increased by 39.0%, 87.6% and 154.6%, respectively. The release amount of K from microcline increased by 44.5%, 88.9% and 158.7%, respectively. First order equation, power function, parabolic diffusion equation and Elovich equation were used to describe the release of K from K-bearing minerals. All the correlation coefficients (r) of the kinetic equations were from 0.708 to 1.000 which showed the most significant correlation (r0.01=0.549). [Conclusion] The amount of potassium released from K-bearing minerals increased significantly by the extractants, and it differed in different K-beating minerals in order of biotite 〉 muscovite 〉 microcline = orthoclase. The power function was the best model to describe the K release of biotite, orthoclase and mierocline, and Elovich equation was the best model for muscovite.