Conversion of coal fly ash into advanced crystalline materials

Abstract

In recent years, coal fly ash disposal has become one concerning environmental problems in Indonesia. Although coal fly ash is remains categorized as hazardous solid waste in several countries, it is also widely known as a valuable material used in various fields, including as a precursor for the synthesis of advanced crystalline materials such as zeolite and geopolymer. Previous studies mainly focused on the utilization of coal fly ash originated from the thermal power plant. This research done to acknowledge the potency of coal fly ash originated from the textile industry to be further converted into new advanced materials through several procedures, such as (1) modification using NaOH solution (FA-Na), (2) synthesized into geopolymer (Geo), and (3) synthesized into zeolite-A (FA-LTA). Characterization of synthesized products conducted using various techniques, i.e., X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), Brunauer-Emmett-Teller (BET), and cation exchange capacity (CEC). The results show that increasing crystallinity, specific surface area, and CEC in the samples are directly proportional to the increasing alkali concentration used. This research has proven that coal fly ash originated from the textile industry and could also synthesize zeolite and geopolymer.