Enhanced antibiotic removal by waste coffee grounds prepared via water washing and KOH activation

Abstract

Abstract This paper proposed a method to remove amoxicillin (AMX) from waste coffee grounds (CGs) using environmentally friendly activated biochar-based adsorbents. KOH-activated adsorbents (activated CGs or ACGs) were prepared by washing with water to avoid using toxic chemicals. The maximum adsorption capacity and kinetics of the ACGs were evaluated using the Freundlich isotherm, Langmuir isotherm, adsorption density, and pseudo-second-order equation. ACG-4a (activated by KOH after washing with water) exhibited a significantly higher adsorption capacity (740.7 mg/g), whereas ACG-4b (activated by KOH after washing with NaOH) exhibited a lower capacity (549.5 mg/g). The specific surface area of the adsorbent is key to the adsorption performance. A comparison of the adsorbents revealed that the ACGs exhibited the highest AMX-adsorbing capacity. Their use has important environmental implications for water pollution mitigation and ecosystem preservation.