Photocatalytic and toxicity evaluation of local dyeing wastewater by aluminium/boron doped WO₃ nanoparticles

The photocatalytic degradation of local dyeing wastewater by Al/B co-doped WO₃ nanoparticles under natural sunlight was investigated. Al/B doped WO₃ nanoparticles were prepared by wet impregnation method and characterized by different analytical tools. Daphnia magna was utilized to evaluate the acute toxicity of the untreated and treated wastewater. HRSEM/HRTEM analysis confirmed the formation of agglomerated spherical shape for WO₃ nanoparticles and mixture of spherical and rod-like morphology for Al/B doped WO₃ nanocomposites. XRD analysis demonstrated the formation of monoclinic phase and the addition of Al and B did not change the phase of WO₃ nanoparticles. The BET surface area of Al/B/WO₃ nanocomposites (66.94 m²/g) is higher than undoped WO₃ (22.49 m²/g). The XPS analysis suggested substitutional replacement of oxygen either by the dopants and existence of W in +6 oxidation state. Bandgap energy reduced from 2.42 eV to 1.70 eV due to the immobilization of Al and B. The Al/B immobilized WO₃ nanoparticles exhibited enhanced photocatalytic performance with 94.0% and 90.0% reduction of COD and TOC level. The concentration of Zn, Fe, Ni, Cu, Cr and Pb in dyeing wastewater reduced after treatment. The kinetic data showed that the photodegradation of the dyeing wastewater by Al/B doped WO₃ nanocomposites was faster than WO₃ alone and the experimental kinetic data were best suitable for pseudo-first order model. The treated wastewater had little or almost no toxicity after 24 h and the photocatalyst can be reused for 5 cycles. Due to its excellent photocatalytic capacity, Al/B co-doped WO₃ nanoparticles exhibited a significant enhancement in the degradation of local dyeing wastewater.