Application of Coal Fly Ash as Adsorbent for Removing Lead (Pb) Metal

Abstract

Coal fly ash (CFA), a major byproduct of coal combustion, poses significant environmental challenges due to its hazardous constituents, including heavy metals. This study explores the potential of CFA sourced from PT PLN Nusantara Power UPK Nagan Raya as a low-cost adsorbent for Pb removal from aqueous solutions. The research investigates the influence of adsorbent dosage and stirring time on adsorption efficiency and capacity, aiming to optimize conditions for practical application in wastewater treatment. Characterization of CFA revealed a composition dominated by silica and alumina, with crystalline phases such as quartz and mullite, which provide active sites for adsorption. Batch experiments were conducted at varying CFA doses (2–8 g) and contact times (30–90 minutes), with pH fluctuations monitored throughout the process. Results indicate that adsorption efficiency increases with higher adsorbent dosage and extended stirring time, achieving a maximum Pb removal of 99.684% at 8 g and 90 minutes. Conversely, adsorption capacity (mg/g) was highest at lower doses, peaking at 0.945 mg/g for 2 g at 90 minutes, reflecting the trade-off between efficiency and capacity due to particle agglomeration and site saturation at higher doses. The findings confirm CFA’s dual mechanism of Pb removal through surface complexation and precipitation, influenced by pH and mineral composition. This study demonstrates that CFA can serve as an effective, sustainable adsorbent for heavy-metal remediation, offering a circular-economy solution for coal combustion residues. Future work should address regeneration strategies and safe disposal of spent adsorbent to prevent secondary contamination.

Keywords: Coal Fly Ash, Adsorption, Lead Removal, Wastewater Treatment, Adsorption Efficiency