Biochar-TiO magnetic nanocomposites for photocatalytic solar-driven removal of antibiotics from aquaculture effluents.

Contamination of surrounding waters with antibiotics by aquaculture effluents can be problematic due to the possible increase of bacterial resistance, making it crucial the efficient treatment of those effluents before their release into the environment. In this work, the application of waste-based magnetic biochar/titanium dioxide (BC/TiO) composite materials on the photodegradation of two antibiotics widely used in aquaculture (sulfadiazine (SDZ) and oxolinic acid (OXA)) was assessed. Four materials were synthesized: BCMag (magnetized BC), BCMag_TiO (BCMag functionalized with TiO), BC_TiO_MagIn and BC_TiO_MagEx (BC functionalized with TiO and afterwards magnetized by in-situ and ex-situ approaches, respectively). SDZ half-life time (t) noticeably decreased 3.9 and 3.4 times in presence of BCMag_TiO and BC_TiO_MagEx, respectively. In the case of OXA, even though differences were not so substantial, the produced photocatalysts also allowed for a decrease in t (2.6 and 1.7 times, in presence of BCMag_TiO and BC_TiO_MagEx, respectively). Overall, the here synthesized BC/TiO magnetic nanocomposites through a circular economy process are promising photocatalysts for a sustainable solar-driven removal of antibiotics from aquaculture effluents.