ROLE OF PHOTOCATALYTIC NANOMATERIALS IN DEGRADING INDUSTRIAL WASTEWATER POLLUTANTS: THE MEDIATING EFFECT OF LIGHT INTENSITY

Abstract

The recalcitrant dyes, pharmaceuticals, phenols and heavy metal found in industrial wastewater of textile, pharmaceutical, chemical, tanning and food-processing industries are difficult to treat and incur very high sludge and energy costs using conventional methods. This paper examines the application of photocatalytic nanomaterials (PNMs) in the degradation of representative pollutants and the effect of the mediating influence of light intensity on the degradation behavior of the material. The experimental design compares three different catalysts; TiO 2, ZnO and a TiO 2 - graphene composite with methylene blue, ciprofloxacin, phenol and Cr (VI) at low to high irradiance. UV- Vis spectrophotometry is used to monitor the pollutant concentrations in 0-120 min. Descriptive statistics, one-way ANOVA to compare catalysts (H1), one-way ANOVA to determine the effects of light intensity (H2) and to study light intensity as a mediator between the type of catalyst and its degradation efficiency (H3) are included in the analysis with the help of SPSS. The findings demonstrate that PNMs are an effective method of boosting degradation, where TiO 2-graphene in medium light has the highest efficiency (approximately 92%). The effect of light intensity is severe and non-linear: low irradiance inhibits activation, medium has an optimal effect with charge separation and radical generation, whereas high irradiance effects recombination losses. Mediation testing establishes that the intensity of light is a partial intermediate between the type and efficiency of catalysts, which means that the benefits that material gain are the greatest in a native irradiance range. Phenol and Cr (VI) degrade slower than ciprofloxacin, which is pollutant-specific. This paper comes to the conclusion that with intentionally managed light and by matching advanced PNMs, especially TiO 2 -graphene, with efficient, scalable, and less-sludge polishing of complex industrial effluents, a precise direction to guide solar and LED-driven reactor design is clear.