A facile route for fabrication of hierarchical porous Nb2O5/ZnO composites with enhanced photocatalytic degradation of palm oil mill effluent

A facile route was demonstrated for the synthesis of hierarchical porous ZnO microspheres based on a surfactant-free chemical solution method. The as-synthesized ZnO were assembled by large numbers of interleaving nanosheets and formed an open porous structure. Under UV irradiation, the as-synthesized ZnO exhibited photocatalytic property on the degradation of palm oil mill effluent (POME) solution. The Nb2O5 decorated ZnO photocatalysts (Nb2O5/ZnO) with enhanced photocatalytic performances were also synthesized via a facile and rapid route. Compared with ZnO, the Nb2O5(3 wt%)/ZnO exhibited the best POME degradation and colour removal efficiencies of 91.7% and 100%, respectively after 240 min irradiation. Phytotoxicity of the POME after Nb2O5/ZnO photocatalysis was significantly reduced via the measurement of radicle lengths of Vigna radiata. The observed results demonstrated the photocatalytic technology using hierarchical Nb2O5/ZnO composites had the potential to effectively purify wastewater.