Spent coffee grounds-derived carbon material as an effective adsorbent for removing multiple contaminants from wastewater: A comprehensive kinetic, isotherm, and thermodynamic study

Abstract

Environmental contamination from various industrial sources poses a significant global concern, demanding effective remediation strategies. This study investigates the efficacy of spent coffee grounds-derived carbon material in removing various contaminants, including organophosphate pesticides, pharmaceutical residues, and cationic dyes from aqueous solutions. Adsorption experiments were conducted at different temperatures (25 °C, 30 °C, and 35 °C), and the adsorption behavior was analyzed using various kinetic (pseudo-first-order, pseudo-second-order, Elovich, intraparticle diffusion) and isotherm models (Freundlich, Langmuir, Temkin, Dubinin-Radushkevich). Our findings reveal a complex adsorption process involving both monolayer and multilayer adsorption on the heterogeneous surface of the material. Temperature significantly influenced adsorption behavior, affecting maximum capacities and interactions. Using a material concentration of 0.5 mg mL−1 increases adsorption capacities for both pesticides, reaching 92.0 mg g−1 for malathion and 259 mg g−1 for chlorpyrifos adsorption. At a material concentration of 0.1 mg mL−1, the carbon material exhibited high adsorption capacities for methylene blue, rhodamine B, amoxicillin, and ceftriaxone, reaching values of 2085 mg g−1, 8250 mg g−1, 82 mg g−1, and 181 mg g−1, respectively. The adsorbent was successfully regenerated using 25 % ethanol solution and reused for at least 10 cycles without significantly impacting the adsorption capacity. These results underscore the potential of spent coffee grounds-derived carbon material as an efficient adsorbent for diverse contaminants, highlighting its promising role in environmental remediation efforts.