斜发沸石凝灰岩的脱阳离子和脱铝以及酸改性凝灰岩上的铵交换
Decationization and dealumination of clinoptilolite tuff and ammonium exchange on acid-modified tuff.
作者信息
Rozić M, Cerjan-Stefanović S, Kurajica S, Maeefat M Rozmarić, Margeta K, Farkas A
机构信息
Faculty of Graphic Arts, Getaldićeva 2, Zagreb, Croatia.
出版信息
J Colloid Interface Sci. 2005 Apr 1;284(1):48-56. doi: 10.1016/j.jcis.2004.09.061.
The paper presents results of investigation of exchange of the clinoptilolite tuff cations with hydrogen ions from HCl solution of concentration 0.1 mmol cm(-3) and ammonium ions solutions of concentrations 0.0071 to 2.6 mmol cm(-3). Molal concentrations, x (mmol g(-1)) of cations exchanged in acid solution and in ammonium ions solutions were compared with molal concentrations of cations obtained by determination of the cation-exchange capacity of clinoptilolite tuff. The obtained results show that at ammonium ion concentrations lower than 0.1 mmol cm(-3), with regard to exchange capacity for particular ions, best exchanged are Na+ ions, followed by Mg2+ and Ca2+ ions, while exchange of K+ ions is the poorest (Na+ > Mg2+ > Ca2+ > K+). At ammonium concentrations from 0.2 to 1 mmol cm(-3) the order is Na+ > Ca2+ > Mg2+ > K+. At concentrations higher than 1 mmol cm(-3) the order is Na+ > Ca2+ > K+ > Mg2+. The results are a consequence of the uptake of hydrogen ions by zeolite samples in ammonium ions solutions at concentrations lower than 1 mmol cm(-3) and indicate the importance of Mg2+ (besides Na+ ions) for the exchange between clinoptilolite cations and H+ ions, in contrast to K+ ions, whose participation in the reaction with H+ ions is the lowest. During decationization of the clinoptilolite in acid solution, best exchanged are Na+, Mg2+, and Ca2+ ions, while exchange of K+ ions is the poorest. Due to poor exchange of K+ and H+ ions and good exchange of Na+, Mg2+, and Ca2+ ions, it is to be assumed that preservation of stability of the clinoptilolite structure is caused by K+ ions present in the channel C. Clinoptilolite is dissolved in the clinoptilolite A and B channels where Na+, Mg2+, and Ca2+ ions are present. On the acid-modified clinoptilolite samples, exchange of ammonium ions is poorer than on natural zeolite. The longer the contact time of the zeolite and acid solution, the worse ammonium ions exchange. It can be assumed that H+ ions exchanged with zeolite cations are consumed for solution of aluminum in the clinoptilolite structure; therefore the concentration of H+ ions as exchangeable cations decreases. In the ammonium ion solution at a concentration of 0.0065 mmol cm(-3), from the acid-modified zeolite samples, Al3+ ions are exchanged best, followed by Na+, Mg2+, Ca2+, and K+ ions. Further to the results, it is to be assumed that exchangeable Al3+ ions available from clinoptilolite dissolution are best exchanged with H+ ions in acid solution.
本文介绍了斜发沸石凝灰岩阳离子与浓度为0.1 mmol cm⁻³的HCl溶液中的氢离子以及浓度为0.0071至2.6 mmol cm⁻³的铵离子溶液中的铵离子进行交换的研究结果。将在酸性溶液和铵离子溶液中交换的阳离子的摩尔浓度x（mmol g⁻¹）与通过测定斜发沸石凝灰岩的阳离子交换容量获得的阳离子摩尔浓度进行了比较。所得结果表明，在铵离子浓度低于0.1 mmol cm⁻³时，就特定离子的交换容量而言，交换效果最好的是Na⁺离子，其次是Mg²⁺和Ca²⁺离子，而K⁺离子的交换效果最差（Na⁺>Mg²⁺>Ca²⁺>K⁺）。在铵浓度为0.2至1 mmol cm⁻³时，顺序为Na⁺>Ca²⁺>Mg²⁺>K⁺。在浓度高于1 mmol cm⁻³时，顺序为Na⁺>Ca²⁺>K⁺>Mg²⁺。这些结果是由于在浓度低于1 mmol cm⁻³的铵离子溶液中沸石样品吸收了氢离子所致，这表明Mg²⁺（除Na⁺离子外）对于斜发沸石阳离子与H⁺离子之间的交换很重要，与K⁺离子相反，K⁺离子与H⁺离子反应的参与度最低。在酸性溶液中斜发沸石脱阳离子过程中，交换效果最好的是Na⁺、Mg²⁺和Ca²⁺离子，而K⁺离子的交换效果最差。由于K⁺和H⁺离子交换不佳以及Na⁺、Mg²⁺和Ca²⁺离子交换良好，可以认为通道C中存在的K⁺离子导致了斜发沸石结构稳定性的保持。斜发沸石在存在Na⁺、Mg²⁺和Ca²⁺离子的斜发沸石A和B通道中溶解。在酸改性的斜发沸石样品上，铵离子的交换比天然沸石差。沸石与酸溶液的接触时间越长，铵离子交换越差。可以认为与沸石阳离子交换的H⁺离子被用于溶解斜发沸石结构中的铝；因此，作为可交换阳离子的H⁺离子浓度降低。在浓度为0.0065 mmol cm⁻³的铵离子溶液中，从酸改性的沸石样品中，Al³⁺离子交换效果最好，其次是Na⁺、Mg²⁺、Ca²⁺和K⁺离子。根据这些结果，可以认为斜发沸石溶解产生的可交换Al³⁺离子在酸性溶液中与H⁺离子交换效果最好。
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