The properties of the NH 4-clinoptilolite. Part 1

Abstract

A clinoptilolite sample from the Zlatokop deposit (Vranje, Yugoslavia) was transformed into the mono-ionic ammonia form. Changes in the behavior of thermally treated NH 4 -clinoptilolite at T ⩾ 473 K were followed by thermal analysis (d.t.a., d.t.g., t.g.), X-ray analysis, chemical and i.r. analysis. On the basis of the results of X-ray analysis and ion exchange data, the content of clinoptilolite (about 85% w/w) and ingredients quartz and feldspars (about 15% w/w) were determined in the original sample from the deposit. Ion exchange did not affect significantly parameters of the unit cell of clinoptilolite. The prepared mono-ionic ammonia form of clinoptilolite was calcined in the temperature range 473–773 K under isothermal conditions. The structural changes in these samples were followed by X-ray analysis, which showed that the crystallinity of the calcined samples was preserved. Thermal analysis showed that the process of dehydration was developing at temperatures from 378 to 416 K, and the exothermal process of oxidation of ammonia to oxides of nitrogen at temperatures from 784 to 810 K. At T ⩾ 673 K the process of dealumination of clinoptilolite framework occurred too, when cationic aluminum formed different forms, depending on the temperature of calcination. By analyzing i.r. spectra of the calcined samples it was established that the degree of dealumination was the same for all samples treated at T ⩾ 673 K.