Abstract:
Semiconductor photocatalysis is touted to be one of the most efficient and cost-effective methods of
degrading organic pollutants in various water matrices. Herein, highly agglomerated WO3 nanoparticles
were synthesized via a facile acid precipitation method and tested on rhodamine B dye as the model
pollutant. The physicochemical properties of the particles were investigated using various
characterization techniques which include X-ray diffraction (XRD), scanning electron microscopy (SEM),
transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) and zeta potential
measurements. The effects of calcination temperature, initial pH, catalyst loading and initial pollutant
concentration were investigated. The results showed that under optimum conditions of 300 °C
calcination temperature, 5 g L−1 catalyst loading, 5 ppm initial pollutant concentration and a pH of 9.5,
the catalyst achieved an excellent degradation efficiency of 96.1% after 4 h of visible light irradiation. The
degradation tests revealed a strong dependence on initial pH with acidic pHs favouring adsorption and
alkaline pHs favouring photocatalysis. The degradation kinetics followed the Langmuir–Hinshelwood
model for catalyst loadings of less than 10 g L−1, which typically describes heterogenous photocatalytic
surface reactions. Scavenging experiments revealed that reactive superoxide and hydroxyl free radicals
were the primary drivers for rhodamine B dye degradation.
