Optimisation of washing cycles to enhance pre-processing of coal fly ash as a precursor for wastewater treatment using response surface methodology

Abstract

Coal, the most abundant and cost-effective fossil fuel critical for global electricity production, especially in developing economies, generates significant coal fly ash (CFA) waste, presenting environmental concerns. This study aims to enhance CFA's suitability as a zeolite precursor for wastewater treatment applications. We selected washing cycles for CFA pre-processing over mechanical activation, chemical modification, and leaching due to its simplicity, costeffectiveness, and efficiency. Accordingly, the CFA was washed multiple times using deionised water within a controlled environment. The activities were carefully monitored to ensure accuracy throughout the experiment. Detailed measurements were continuously taken of key factors such as the pH, solution conductivity, and CFA particle size across a range of conditions, including variations in temperature, number of washing cycles, and stirring duration. These observations were essential for method optimisation through response surface methodology (RSM). Findings of this research suggest that the optimal conditions are achieved at 6 washing cycles with a 3-minute stirring time and a temperature of 30 0C. These parameters enhance efficiency while reducing costs, demonstrating how waste material can become a valuable resource for sustainability. Further research on stirring rate and solid-toliquid ratio is recommended to optimise CFA pre-processing for high-yield zeolite production in wastewater treatment.