DOI: https://doi.org/10.55373/mjchem.v28i2.203

Keywords: Spent coffee grounds, lead(II), removal, adsorption, response surface methodology, waste valorisation

Abstract

Water pollution caused by heavy metals such as lead poses a serious global threat to both environmental and human health. This study evaluated the effectiveness of untreated spent coffee grounds (SCG) as a low-cost and eco-friendly adsorbent for removing lead(II) from aqueous solutions. Key adsorption parameters such as initial lead concentration, pH, and adsorbent dosage were optimized using response surface methodology (RSM) based on a Box-Behnken design. All parameters and some of their higher-order interactions significantly influenced lead removal. Under optimal conditions of 100 ppm initial lead concentration, pH 5.54, and 10.00 g/L adsorbent dosage, 97.53 % lead removal was achieved upon experimental validation, closely matching the 100 % removal predicted by the RSM model confirming its reliability. SCG also showed comparable performance to activated carbon, which had a 97.05 % removal efficiency. Characterization through ATR-FTIR and SEM-EDS confirmed lead adsorption onto SCG surfaces. The process followed the Langmuir isotherm model and pseudo-second-order kinetics with a maximum adsorption capacity of 68.03 mg/g. These findings highlight SCG’s potential as a sustainable alternative for lead(II) remediation in contaminated water systems.