Abstract

In this work, we studied the effect of physicochemical properties of synthesized biochar/iron oxide composites on tetracycline (TC) removal from an aqueous system. The TC removal involved adsorption and degradation using Fenton-like and Photo-Fenton-like reactions. The results showed that the adsorption capacity of synthesized materials inversely varied with the pyrolysis temperature, achieving removal percentages of 72 %, 65 %, and 56 % for materials developed at pyrolysis temperatures of 400 °C, 500 °C, and 600 °C, respectively. Regarding the Fenton-like and Photo-Fenton-like processes, BC-500-m exhibited the best catalytic performance attributed to its structural conformation and phase composition of iron oxide. This enabled the removal of 84 % of tetracycline. BC-500-m also showed a low reaction rate, resulting in a 53 % removal of TC through the Photo-Fenton process. However, a high degradation capacity and potentially mineralizable by-products into CO2 and H2O suggest that photo assistance establishes a cleaner and more ecosystem-friendly reaction mechanism. The reuse capacity decreased from 84 % to 12.5 % after five cycles, indicating a reduced availability of active sites to remove TC due to the possible generation of complexes between Fe+2 and the TC. It is a significant advancement that through the thermochemical valorization of lignocellulosic resources such as brewer's spent grains (BSG), it is possible to establish sustainable and ecosystem-friendly bifunctional removal mechanisms capable of mediating the remediation of water with the presence of pharmaceuticals through a circular economy.