Comparative Adsorption of Copper Ion (Cu2+) onto Raw and NaOH-Modified Coal Fly Ash at Various Initial Concentrations

Ilham Aswi Syaputra; Farrah Fadhillah Hanum; Aster Rahayu; Rimadina Sukmasuci Lestari

doi:10.32734/jcnar.v7i2.25935

Authors

Ilham Aswi Syaputra Magister of Chemical Engineering, Faculty of Industrial Technology, Ahmad Dahlan University, Yogyakarta, 55164, Indonesia
Farrah Fadhillah Hanum Magister of Chemical Engineering, Faculty of Industrial Technology, Ahmad Dahlan University, Yogyakarta, 55164, Indonesia
Aster Rahayu Magister of Chemical Engineering, Faculty of Industrial Technology, Ahmad Dahlan University, Yogyakarta, 55164, Indonesia
Rimadina Sukmasuci Lestari Magister of Chemical Engineering, Faculty of Industrial Technology, Ahmad Dahlan University, Yogyakarta, 55164, Indonesia

DOI:

https://doi.org/10.32734/jcnar.v7i2.25935

Keywords:

Coal Fly Ash, NaOH Modification, Copper Ion Removal, Adsorption, Wastewater

Abstract

Coal fly ash, a voluminous industrial solid by-product generated during coal combustion in thermal power facilities, has garnered considerable scientific attention as a cost-efficient sorption material for eliminating heavy metal contaminants from industrial effluents. This study comparatively evaluates the adsorption performance of unmodified coal fly ash (FA) and NaOH-modified coal fly ash (FA-NaOH) for Cu²⁺ removal from synthetic wastewater using a batch system. Both adsorbents were characterized for moisture content and iodine adsorption capacity. Equilibrium sorption experiments were conducted across a Cu²⁺ initial concentration of 25–125 mg/L using 7.5 g of adsorbent in 200 mL solution at 500 rpm for 60 minutes at room temperature. Residual copper was analyzed by Atomic Absorption Spectrophotometry (AAS). The FA-NaOH consistently outperformed FA, achieving removal efficiencies between 83.01% and 99.98%, and a maximum adsorption capacity (qm) of 2.4325 mg/g compared to FA 2.3250 mg/g. The equilibrium data for adsorption aligned better with the Langmuir isotherm (R² = 0.9077), particularly for FA-NaOH, indicating monolayer adsorption at homogeneous active sites. These results collectively affirm that alkaline activation markedly amplifies the Cu²⁺ uptake capacity of coal fly ash, confirming NaOH-modified coal fly ash as an economically accessible and ecologically sound strategy for heavy metal removal in wastewater treatment.

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