改型斜发沸石在Na^+-Ca^(2+)-Mg^(2+)和NH_4^+-Ca^(2+)-Mg^(2+)水溶液体系中的离子交换平衡

Ion Exchange Equilibria between the Modified Clinoptilolite and Aqueous Solutions of Na^+-Ca^(2+)-Mg^(2+) and NH_4^+-Ca^(2+)-Mg^(2+) Systems

研究了Na+-Ca2+-Mg2+与钠型斜发沸石和NH4+-Ca2+-Mg2+与铵型斜发沸石的离子交换平衡,分别测定出2个体系的离子交换平衡数据,并利用三维坐标绘制出三元离子交换平衡等温面,计算出改型沸石对体系中离子的分离因数.结果表明,在Na+-Ca2+-Mg2+溶液体系中,Na+的分离因数>10,Ca2+的在0.4～10之间,Mg2+的小于0.4,斜发沸石离子交换顺序为Na+>Ca2+>Mg2+,且温度升高Ca2+和Mg2+的交换能力增强,而低温则有利于沸石对Na+的选择;在NH4+-Ca2+-Mg2+溶液体系中,NH4+的分离因数>15,Ca2+的在0.2～1.5之间,Mg2+的小于0.2,斜发沸石离子交换顺序为NH4+>Ca2+>Mg2+,且温度升高Ca2+和Mg2+的交换能力增强,NH4+的选择性降低.

The ion exchange equilibria between the modified clinoptilolite and the ternary solution systems of Na＋-Ca2＋-Mg2＋ and NH4＋-Ca2＋-Mg2＋ were investigated.The ion exchange equilibrium data of the above systems were measured respectively.Based on the experimental results,the ion exchange isothermic surfaces were constructed using three-dimensional coordinates,and the ternary separation factors of the systems calculated.The results show that the separation factors of Na＋ is over 10,Ca2＋ between 0.4 and 10,and Mg2＋ below 0.4 in the Na＋-Ca2＋-Mg2＋ system,therefore the ion exchange selective sequences of the clinoptilolite is Na＋Ca2＋Mg2＋,and higher temperature is in favor of the selectivity of the zeolite to Ca2＋ and Mg2＋,but lower temperature is propitious to the adsorption of the zeolite to Na＋.The separation factor of NH4＋ is over 15,Ca2＋ between 0.2 and 1.5,and Mg2＋ below 0.2 in the NH4＋-Ca2＋-Mg2＋ system,so the ion exchange selective sequences of the clinoptilolite is NH4＋Ca2＋Mg2＋,and higher temperature is in favor of the selectivity of the zeolite to Ca2＋ and Mg2＋,otherwise lower temperature is propitious to the adsorption of the zeolite to NH4＋.