阳离子改型蛭石的铵离子交换平衡特性

对经Na^＋，Ca^2＋、Mg^2＋等不同离子处理的改型蛭石在不同pH和温度条件下进行了铵离子交换性能的研究。结果表明，交换反应均在前60min速率最快，约120min就趋向于平衡：铵离子交换总量均随pH变化而波动，在pH=7点上取最大值，且全交换容量按镁型蛭石、钙型蛭石，钠型蛭石顺序依次增大，每100g蛭石分别为59.32，71.89、92.85mmol；改型蛭石对NH^＋4等温交换吸附与Langmuir方程相符。表明改型蛭石对NH^＋4的吸附主要是单分子层的化学吸附。

Characterization of Exchange Equilibria of Ammonium Ions on Cation-Modified Vermiculite

Experiments were designed under different pH and temperature conditions to analyse the NH_4~+ exchange capacities of Na~+, Ca~(2+), Mg~(2+), and etc. modified vermiculite minerals respectively. The results indicated that the exchange reactions took place most rapidly within the first 60minutes and approached to an equilibrium by about 120minutes. The NH_4~+ exchange capacity of the minerals varied with pH value, and the peak values of 59.32mmol per 100g of Mg~(2+)-vermiculite, 71.89mmol per 100g of Ca~(2+)-vermiculite, and 92.85mmol per 100g of Na*-vermiculite occurred at pH7. Characterization of the exchange and adsorption isotherm of NH_4~+ on cation-modified vermiculite coincided with Langmuir equation, i.e., the adsorption of NH_4~+ belonged to a monomolecular chemical adsorption.