Direct synthesis of sodalite from Indonesian kaolin for adsorption of Pb²⁺ solution, kinetics, and isotherm approach

Indonesian kaolin was used as precursor for synthesis of sodalite. Synthesis parameters were optimized by varying the Si/Al ratios, stirring and aging conditions, and water composition. X-ray diffraction (XRD), Fourier Transform Infra Red (FTIR), Scanning Electron Microscope-Energy Dispersive X-ray (SEM-EDX), and Particle Size Analyzer (PSA) were used to characterize sodalite. The potential of sodalite as adsorbent for heavy metal Pb2+ ions removal from waste water was investigated in this work. The uptake adsorption capacities of sodalite was 90-100 mg/g from synthesized sodalite crystallized for 24 and 48 hours, and commercial silica. The kinetic of Pb²⁺ adsorption was a pseudo second order reaction and the adsorption coefficients was followed Langmuir adsorption isotherm.