A Study on the Immobilization of Toxic Metal Ions by using Prepared Kaolinite and Fly Ash-based Geopolymers

Geopolymers are the synthetic analogues of natural zeolitic materials which are aluminosilicate materials. They can be used in the immobilization of heavy metal contaminants as well as in the structural products. Thus, the aim of this research work is to study the use of kaolinite and fly ash-based geopolymer to immobilize heavy and toxic metals in application of the removal of toxic metals from contaminated wastewater and the extraction of heavy metals from their leached solutions. The characterization of kaolinite samples from Taungnauk and Kyauktaga and fly ash samples from industries located at Tigyit and Pyin Oo Lwin were carried out by using EDXRF, SEM, XRD, FTIR and TG-DTA instrumental techniques. Moreover, the chemical compositions of the samples were also analyzed by using standard conventional methods. The geopolymer materials were prepared by using different ratios of kaolinite and fly ash with different concentrations of sodium hydroxide at room temperature. These geopolymer samples were analyzed and characterized by conventional methods and modern instrumental techniques such as EDXRF, SEM, XRD, FTIR and TG-DTA. Moreover, some mechanical properties of the prepared geopolymers, such as compressive strength and tensile strength were also carried out. Since this research work concerns with the use of geopolymers for immobilization of heavy and toxic metals, the removal of toxic metal ions in wastewater samples from different industries by using prepared geopolymer samples (H1-H4). Among the four geopolymer samples, geopolymer sample (H1) was found to be the maximum leaching property (i.e., the immobilization efficiency exceeds 92.9% when Pb2+ ions contained in metal loaded geopolymer (H1). Moreover, the removal percents of Pb2+ , Cd2+ and As3+ions from wastewater samples were found to be in the range of 67.5%, 59.5% and 52.5% for Textile Mill (Wundwin), whereas the removal percents of Pb2+ and As3+ions were 65.7% and 49.4% for Battery Industry (Shwe Pyi Thar) by using prepared geopolymer (H1). Thus the process of removal of the toxic metal ions from wastewater sample by kaolinite and fly ash-based geopolymers can be used as an effective alumino-silicate polymeric material in the treatment of industrial influents