Synthesis of zeolite A using kaolin from Ethiopia and its application in detergents

Abstract

Most commercial manufacturers of soap and detergents in developing countries and few developed countries are still using environmentally unfriendly phosphate based materials like sodium tripolyphosphate as detergent builders. Detergents that contain phosphorus contribute to the eutrophication of fresh water bodies. To surmount this problem, many detergent manufacturers are currently using zeolite A as the builder material which has proved to be a better substitute for phosphorus containing additives. Despite its remarkable potential, the high cost of zeolite A has limited its effective use in detergents. In this work detergent-grade zeolite A has been synthesized from the Ethiopian kaolin collected from the southern part of the country with the molar gel composition of Na₂O:Al₂O₃:2SiO₂:37H₂O. Two routes are surveyed for the synthesis of zeolite A: alkali fusion using raw kaolin and conventional hydrothermal synthesis. The resulting zeolite A samples are studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), chemical analysis (ICP) and thermogravimetry (TGA). Moreover, the cation exchange capacity (CEC) of >310 mg CaCO₃ per g as well as the average particle size of 3 μm of zeolite A is found to be satisfactory to be used as a detergent builder. This study also focused on evaluating its potential use as a detergent by analyzing some physicochemical properties like foam height, pH value, moisture content and alcohol and water insolubility of the formulated detergent using our synthetic zeolite A. The result showed that the synthesized detergent has comparable detergency to commercial brands of powder detergents.