Solar photocatalytic application of NbO₂OH as alternative photocatalyst for water treatment

Water recycling and industrial effluents remediation are a hot topic of research to reduce the environmental impact of the human activity. Persistent organic pollutants are highly recalcitrant compounds with hazardous effects associated to their fate in water bodies. Several novel technologies have been developed during the last decades to deal with this novel contamination. However, the natural sources and idiosyncrasy of each country lead to the potential application of different technologies. In this context, we have focused on the development of phocotalytic treatment of solutions containing dyes using a novel photocatalytic material, the NbO₂OH. The NbO₂OH was synthesized and characterized with different techniques. Several assays demonstrated the solar photoactivity of this novel oxyhydroxide catalyst, achieving complete decolorizations after 10 min of treatment under optimal conditions of 1.0 g L⁻¹ NbO₂OH photocatalyst loading, 0.1 M of H₂O₂ as electron scavenger, pH 4.0 and methyl orange concentrations up to 15 mg L⁻¹. Also, the catalyst recuperation demonstrated the potential reuse of this photocatalyst without losing catalytic response after five cycles. This work is of significant importance because niobium is a natural resource, mainly extracted in Brazil and the annual global sunlight irradiation in the near-equatorial region of northeast Brazil is over the average solar irradiation of the planet. Thus, the solar photocatalytic treatment using NbO₂OH in northeast Brazil appears as a highly potential environmental-friendly nanotechnology to mitigate the water pollution. - Highlights: • Solar photocatalysis as low cost and environmentally friendly nanotechnology. • NbO₂OH alternative photocatalyst for Brazil as owner of major niobium resources. • Fast decolorization due to the synergistic interaction between catalyst and H₂O₂. • Potential applicability to decolorize textile effluents. • NbO₂OH photocatalyst reutilization without losing photocatalytic activity.