Valorization of coffee husks for the sustainable removal of pharmaceuticals from aqueous solutions

Abstract

The contamination of wastewater with pharmaceutical compounds represents a growing environmental challenge due to the inefficiency of conventional treatment systems in removing these emerging contaminants. The coffee husk (CH) is a promising bioadsorbent due to its abundant availability as a byproduct of coffee production. This study focuses on using untreated CH as an adsorbent for removing acetaminophen (ACE) and ciprofloxacin (CIP) while exploring the impact of pyrolysis temperature on the adsorption efficiency of these pharmaceutical compounds. The results reveal an excellent CH performance in removing CIP, achieving 64% removal with a maximum adsorption capacity of 37.00 mg/g. Increasing the pyrolysis temperature during the heat treatment of coffee husks significantly affects the adsorption of CIP. This behavior is primarily due to the reduction in functional groups, which are essential for facilitating the adsorption of CIP onto the resulting biochar. Thermodynamic parameters (ΔH° > 0 and ΔG° > 0) indicate that CIP adsorption on CH is an endothermic and not spontaneous process. The removal efficiency of CIP on CH for synthetic wastewater and urine matrices showed that CH can effectively remove CIP from wastewater. Finally, the reuse of CH as a bioadsorbent highlights its potential to contribute to water quality improvement and environmental preservation.