Utilization of power plant wastes for preparing zeolites as functional materials and its applications in environment and petrochemical industry

Fly ash is a by-product of coal power plants and is known as one of the wastes creating an environmental impact in the form of both air and water pollution. The amount of fly ash at Mae Moh Power Plant, Lampang Province was found to have increased rapidly, and one of the methods to reasonably remedy the issue is to use fly ash to prepare zeolite as functional material. This research aims to utilize fly ash from the Mae Moh power plant as a low-cost silicon source for the synthesis of zeolite A, used as a functional material for environmental applications in the petrochemical
industry. The synthesized zeolite A was identified through X-ray diffraction analysis (XRD), X-ray fluorescence techniques (XRF), Scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX), Attenuated Total Reflection Fourier-transformed infrared spectroscopy (ATR-FTIR) and surface area and porosity analyzers (Brunauer-Emmett-Teller; BET) to confirm that it is zeolite A. The synthesized zeolite A was then used as an adsorbent for the removal of malachite green, cadmium, and lead from aqueous solutions. A batch system was applied to study the adsorption efficiency. The optimum parameters were studied, namely, the amount of adsorption and contact time for absorption. Additionally, adsorption isotherms, kinetics, and thermodynamics for the removal of malachite green and heavy metals, cadmium, and lead, were also evaluated. The optimal amount of zeolite A for the adsorption of malachite green, cadmium, and lead was 10, 8 and 6 g/L, respectively. The optimal contact time for the absorption of malachite green, cadmium, and lead were 60, 30 and 15 minutes, respectively. The adsorption efficiency for malachite green was 98.71%. Furthermore, the reuse of zeolite A was also studied. The results showed that the synthesized zeolite A can be used up to 8 times and the adsorption efficiency was still greater than 85%. The adsorption efficiency of the heavy metals cadmium and lead was 96.44% and 97.95%, respectively. In addition, the reusability of zeolite A was also studied. The results showed that the synthesized zeolite A can be reused up to 5 times and the cadmium adsorption efficiency was still greater than 80%. The adsorbent corresponds to the Langmuir isotherm, indicating monolayer adsorption. The study of adsorption kineties corresponded to a pseudo second order model. The values obtained by calculating entropy (AS°), enthalpy (AH°), and Gibbs free energy (AG°) show that the adsorption process is an endothermic reaction and a spontaneous process. In addition, zeolite A was modified with 5 molar potassium hydroxide (KOH) to be used as a catalyst in the transesterification reaction by switching from palm oil to biodiesel. The results showed that the basic strength analysis was 9.3