INVESTIGATION OF THERMAL AND STRUCTURAL PROPERTIES OF NITRIC, HYDROCHLORIC AND SULPHURIC ACID-TREATED ZEOLITE

Abstract

In this study, in order to consider the effect of the hydrochloric acid (HCl), nitric acid (HNO3) and sulphuric acid ($H_2SO_4$) treatments on thermal and structural properties, zeolite was modified with 1 M acid solutions at 70 oC during 4 h using batch method. The structural and thermal properties of zeolites were studied by X-ray diffraction (XRD), X-ray fluorescence (XRF), thermogravimetric analysis (TG), differential thermogravimetric analysis (DTG) and differential thermal analysis (DTA). Quantitative XRD analysis show that the natural zeolite mainly consists of mordenite and clinoptilolite with varying amounts of quartz, feldspar and clay mineral. TG-DTG and DTA curves of all zeolite samples were obtained in the temperature range between 30 and 1000 oC. Based on the TG results, the total mass losses for all acid-treated samples (8.51-8.44 %) are less than that of the natural (Z) sample (10.14 %). $SiO_2/\;Al_2O_3$ ratio of the natural zeolite sample (Z) increased from 5.6 to 9.8, 9.7 and 8.8 in the Z-N, Z-H and Z-S samples, respectively, indicating the removal of the significant amount of aluminum from the zeolite structure.