Zeolitic Materials From Rice Husks And Water Hyacinth For Removal Of Lead, Cadmium, Methylene Blue And Suspended Particles From Wastewater

ABSTRACT

About 17.2 million people in Kenya have no access to clean water. The major factors contributing to lack of clean water include rapid population growth, droughts, forest degradation, poor management of water supply and water contamination. Lack of clean water may worsen as industrial development and population grows as projected if drastic measures are not taken immediately. Use of rice husks and water hyacinth that is known to contaminate and jam water bodies to create water treatment products is highly desirable. This would help treat contaminated water as well as help control or manage the water hyacinth and rice husks. Thus, the present study investigated the chemical composition and adsorption capacity of water hyacinth ash (WHA), water hyacinth ash residue (WHAR) and rice husk ash (RHA), for removal of Pb2+ and Cd2+and their abilities to remove colour and turbidity from wastewater. Mixtures of the ashes were used to prepare zeolitic materials A (ZMA) and B (ZMB). The instruments used in this study were FAAS, XRF, pH meter, UV- Spectrometer, Centrifuge and Turbidity meter. Batch experiments were carried out to determine the effect of metal ion concentration, initial pH, contact time (t), temperature (T) and adsorbent dosage on the percentage removal of Pb2+, Cd2+ methylene blue and suspended particles by the ashes and their zeolitic products. Adsorption data was analyzed using Langmuir and Freundlich isotherm models. The adsorption capacities for Pb2+ by RHA, WHAR, ZMA, ZMB and WHA was 37.04, 83.33, 142.86, 278.6 and 61.69 mg/g respectively while that of Cd2+ was 56.89 mg/g for WHAR, 52.00 mg/g for WHA, 22.22 mg/g for ZMB, 3.745 mg/g for RHA and 11.24 mg/g for ZMA. The results showed that WHAR and ZMB were the best adsorbents in removing of Pb2+, Cd2+ and suspended particles from wastewater. This implies that incorporating WHAR in the synthesis of zeolitic material enhances adsorption of Pb2+andCd2+ from wastewater and also imparts ability to remove suspended particles