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首页> 外文期刊>International Journal of Environmental Research and Public Health >Ammonium Removal from Aqueous Solutions by Clinoptilolite: Determination of Isotherm and Thermodynamic Parameters and Comparison of Kinetics by the Double Exponential Model and Conventional Kinetic Models
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Ammonium Removal from Aqueous Solutions by Clinoptilolite: Determination of Isotherm and Thermodynamic Parameters and Comparison of Kinetics by the Double Exponential Model and Conventional Kinetic Models

机译：斜发沸石去除水溶液中的铵：等温线和热力学参数的确定以及双指数模型和常规动力学模型的动力学比较

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摘要

The adsorption isotherm, the adsorption kinetics, and the thermodynamic parameters of ammonium removal from aqueous solution by using clinoptilolite in aqueous solution was investigated in this study. Experimental data obtained from batch equilibrium tests have been analyzed by four two-parameter (Freundlich, Langmuir, Tempkin and Dubinin-Radushkevich (D-R)) and four three-parameter (Redlich-Peterson (R-P), Sips, Toth and Khan) isotherm models. D-R and R-P isotherms were the models that best fitted to experimental data over the other two- and three-parameter models applied. The adsorption energy (E) from the D-R isotherm was found to be approximately 7 kJ/mol for the ammonium-clinoptilolite system, thereby indicating that ammonium is adsorbed on clinoptilolite by physisorption. Kinetic parameters were determined by analyzing the nth-order kinetic model, the modified second-order model and the double exponential model, and each model resulted in a coefficient of determination (R2) of above 0.989 with an average relative error lower than 5%. A Double Exponential Model (DEM) showed that the adsorption process develops in two stages as rapid and slow phase. Changes in standard free energy (?G°), enthalpy (?H°) and entropy (?S°) of ammonium-clinoptilolite system were estimated by using the thermodynamic equilibrium coefficients.
机译：本研究研究了斜发沸石在水溶液中的吸附等温线，吸附动力学及热力学参数。从批次平衡测试获得的实验数据已通过四个两个参数（弗氏，兰格缪尔，滕普金和Dubinin-Radushkevich（DR））和四个三个参数（Redlich-Peterson（RP），Sips，Toth和Khan）等温线模型进行了分析。 。与其他应用的两参数和三参数模型相比，D-R和R-P等温线是最适合实验数据的模型。对于铵-斜发沸石系统，发现来自D-R等温线的吸附能（E）约为7kJ / mol，从而表明铵通过物理吸附被吸附在斜发沸石上。通过分析n阶动力学模型，改进的二阶模型和双指数模型确定动力学参数，每个模型的测定系数（R2）均大于0.989，平均相对误差低于5％。双指数模型（DEM）表明，吸附过程分为快速和慢速两个阶段。利用热力学平衡系数估算铵-斜发沸石系统的标准自由能（ΔG°），焓（ΔH°）和熵（ΔS°）的变化。

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