Low-temperature synthesis of zeolite from perlite waste - Part I: review of methods and phase compositions of resulting products

In this paper a review of the recent studies on the synthesis of zeolites from expanded perlite under hydrothermal conditions is presented. Attention is paid to possible outcomes of synthesis from low cost glass material, such as perlite. The study also investigates the phase composition of zeolitic materials obtained by modification of by-product derived from an expanded perlite production process. The synthesis was made using the hydrothermal method with sodium hydroxide under autogenous pressure at a temperature below 100 degrees C for 1 to 72 h. It was possible to obtain a zeolitic material at a temperature as low as 60 degrees C using 4.0 M NaOH. The X-ray diffraction pattern showed the biggest peak intensity of zeolite X with 4.0 M NaOH at the temperature of 70 degrees C. During synthesis at higher temperature zeolite Na-P-1 (with 3.0 M NaOH at 90 degrees C) and hydroxysodalite (with 5.0 M NaOH at 90 degrees C) were obtained.