Abstract

Biochar, a carbon source, obtained from the valorization of biowaste from brewed coffee (COFF) and chitosan (CTO), were incorporated in different amounts in ZnO particles by co-precipitation method aiming to enhance ZnO photocatalytic properties. Oxidized biochar were also prepared to reduce their hydrophobicity and to enhance the interaction between the ZnO. The ZnO/biochar materials were characterized by different techniques (TGA, XRD, FTIR, DRS, BET and Raman spectroscopy) and the photocatalytic properties investigated using phenol as standard pollutant. Biochar enhanced the efficiency, when in proper amounts, up to 20 wt%, outperforming the pristine ZnO and the benchmark ZnO/reduced graphene oxide. Optimum phenol degradation efficiency was found for the composite with 3.4 wt% of carbon (ZnO/2-COFF). At lower carbon concentration (6 wt%) the opposite was observed. ZnO/oxidized biochar composites showed the poorest phenol removal (99%, 30 min), carbamazepine (70%, 60 min), bisphenol A (70%, 60 min) and ibuprofen (95%, 60 min) with 0.5 g/L of catalyst. The results indicated the advantageous of using biochar from biowaste as a carbon source to enhance the ZnO catalyst properties for water remediation.