Spent coffee grounds present a valuable resource for natural reducing agents and cellulose. This work demonstrates the valorization of spent coffee grounds (CG) to produce composite aerogels for arsenic removal from wastewater. Phenolic compounds extracted from CG were used as a natural reducing agent to produce iron particles in the aerogel. Cellulose (CC) was further extracted from CG and used as an aerogel reinforcement. The composite aerogels were prepared via one-pot synthesis by mixing a chitosan solution, a FeCl₃ solution, coffee extract, and CC. The synergy between chitosan and iron particles enhanced arsenic adsorption via interactions with amine functional groups and the incorporated iron particles. The aerogel exhibited satisfactory mechanical stability and could effectively remove arsenic from petroleum-refining wastewater.
