Development of an Original Photocatalytic System Based on Bismuth Vanadate Composites for Simultaneous Degradation of Pharmaceutical Micropollutants in Nigerian Hospital Wastewater

Pharmaceutical micropollutants discharged from Nigerian hospitals and pharmaceutical manufacturing facilities into receiving water bodies represent an emerging environmental and public health challenge that existing wastewater treatment infrastructure is not designed to address. Bismuth vanadate, a visible-light-active semiconductor photocatalyst, offers a promising platform for pharmaceutical micropollutant degradation, but its performance limitations and the need for optimisation in the Nigerian context demand an original research contribution combining materials design with mechanistic understanding and real-world validation. This study developed a novel bismuth vanadate-reduced graphene oxide-cobalt ferrite ternary nanocomposite photocatalyst with magnetically separable properties for simultaneous visible-light degradation of pharmaceutical micropollutants. The nanocomposite was synthesised by a hydrothermal co-precipitation method, and its structural, optical, magnetic, and photocatalytic properties were comprehensively characterised. Degradation performance was evaluated for a mixture of ten pharmaceuticals, including antibiotics, analgesics, hormones, and antidiabetics, in simulated and real hospital wastewater from three Nigerian university teaching hospitals. Mechanistic investigation using radical scavenging experiments, electron paramagnetic resonance, and in situ Fourier-transform infrared spectroscopy identified superoxide radicals and singlet oxygen as the primary reactive species responsible for pharmaceutical degradation. Complete mineralisation of amoxicillin, ciprofloxacin, and ibuprofen was achieved within 90 minutes under visible light irradiation in hospital wastewater matrix, with minimal matrix effects compared to ultrapure water experiments. The magnetically separable composite maintained 92 percent activity after 10 catalytic cycles. This work constitutes an original contribution to photocatalytic water treatment chemistry with direct relevance to Nigerian healthcare facility wastewater management.

Keywords: bismuth vanadate, photocatalysis, pharmaceutical micropollutants, hospital wastewater, Nigeria