Solar photocatalytic mineralization of antibiotics using magnetically separable NiFe2O4 supported onto graphene sand composite and bentonite

Adsorbent supported photocatalysis is developing as a potential waste water treatment technology. In this work, NiFe 2 O 4 was supported onto graphene sand composite (GSC) and bentonite (BT) supported to prepare magnetic NiFe 2 O 4 /GSC and NiFe 2 O 4 /BT nanocomposties. Graphene sand composite (GSC) was prepared by graphitization of sugar over river sand. The size of NiFe 2 O 4 /BT and NiFe 2 O 4 /GSC was found to be 50 and 60 nm respectively. Mesoporous nature of prepared photocatalysts was confirmed by BET adsorption/desorption experiments. NiFe 2 O 4 /GSC and NiFe 2 O 4 /BT exhibited ferromagnetic behaviour and could be separated from treated water using external magnetic field. The band gaps of NiFe 2 O 4 /GSC and NiFe 2 O 4 /BT were found to be 2.41 and 2.42 eV, respectively. The adsorption and photocatalytic activity of NiFe 2 O 4 /GSC and NiFe 2 O 4 /BT was tested for the mineralization of ampicillin (AMP) and oxytetracycline (OTC) antibiotics under solar light. The adsorption process had significant effect on the mineralization of AMP and OTC. Simultaneous adsorption and degradation (A + P) process were the most efficient for antibiotic degradation. The complete mineralization of antibiotics was obtained using NiFe 2 O 4 /GSC/A + P and NiFe 2 O 4 /BT/A + P catalytic processes. The kinetics of mineralization were explored using power law model. Magnetically recoverable NiFe 2 O 4 /GSC and NiFe 2 O 4 /BT are recyclable and displayed significant recycle efficiency and quick recovery for 10 consecutive catalytic cycles.