Optimization of chloride removal from fly ash: a step towards sustainable waste management

Fly ash, a hazardous waste byproduct of incineration processes, necessitates proper management to mitigate environmental risks. Among the disposal and reuse methods, water washing stands out as a cost-effective solution. This study utilized the response surface methodology to optimize chloride extraction from fly ash through washing. Experimentation encompassed varying washing times and liquid-to-solid ratios, with an emphasis on identifying key factors influencing optimal outcomes. Utilizing Design-Expert software, experiments spanned liquid-to-solid ratios of 1–10 (mL/g) and mixing times of 2–240 min. Results revealed that the liquid-to-solid ratio significantly impacted chloride removal, with ratios below 5 yielding suboptimal outcomes. Additionally, analytical techniques, including X-ray diffraction, X-ray fluorescence, and scanning electron microscopy, were employed. The study aims to optimize parameters for effective chloride extraction while minimizing water consumption. Findings underscore the efficacy and cost-efficiency of water washing in chloride reduction, contingent upon the appropriate ratio and time selection. Maximum chloride removal occurred at a liquid-to-solid ratio of 10 mL/g and a mixing time of 121 min, yielding 41.51 mol of extracted chloride.