Fe-biochar supported catalysts for Diclofenac photocatalytic degradation

Two waste wood biomass-derived biochars (T1 and T2) were investigated as potential supports to develop iron (Fe)-based catalysts for the removal of Diclofenac (DFC) through a heterogenous photo-Fenton-like process. The resulting samples, Fe/T1 and Fe/T2, were characterized using various techniques, including EA, XRPD, TGA-DTG, BET, FT-IR, SEM-EDX, and TEM-EDX, and compared with pristine T1 and T2. The Fe/T2 catalyst showed excellent adsorption performances similar to the original substrate, achieving removal efficiencies in the 97–100% range for initial DFC concentrations from 10 to 40 mg L–1. The adsorption kinetics followed a Pseudo-Second-Order model (PSO), while the adsorption isotherms were best described by the Freundlich model, conforming to heterogeneous surfaces. Despite a maximum removal efficiency of about 62% was obtained at the higher DFC concentration (100 mg L–1) through adsorption, a visible improvement up to 93% was guaranteed when unconventional photocatalytic degradation was as well applied. Furthermore, the residual TOC, equal to 5.53%, resulted to comply with the current legal discharge limits. Therefore, this study introduced an innovative approach for DFC removal via a photo-Fenton-like process, which thus can overcome some limitations of conventional systems by operating under alkaline conditions and on higher DFC concentrations.