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

Abstract

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.