Water contamination is a widespread problem that jeopardizing life on earth. The fact that water is capable of dissolving many different substances makes it uniquely vulnerable to pollution. Many human activities are causing direct and indirect water pollution such as landfill, industrial runoff, leaks and spills, mining, etc. Therefore, major steps forward should be taken to treat those water bodies. Cutting edge nanotechnologies are currently invested in order to mitigate water contamination problems and provide environmentally sound solutions. Adsorption and photodegradation using photoactive nanomaterials are considered one of the states of technologies that are used in industrial water purification.
This study evaluates the effective photodegradation properties of TiO2 brookite nanoparticles for the removal of binary aqueous mixtures of the anionic dyes: Alizarin Red S (ARS) and Bromocresol green (BCG). Batch adsorption experiments were conducted to investigate the effect of dyes concentration, contact time, and temperature effect. The adsorption isotherms were fitted for the single adsorption using the models of Langmuir, Freundlich and Sips, while the binary adsorption isotherms were fitted using the Extended-Sips model. The photodegradation experiments for the adsorbed dyes were achieved using UV light irradiation (6 W, λmax = 312 and 365 nm). Overall, post-adsorption photodegradation preliminary results showed high selectivity towards ARS molecules in the presence of BCG molecules. In addition, the adsorption process was spontaneous in nature with endothermic behavior for both anionic dyes. The TiO2 nanoparticles were successfully regenerated using UV irradiation. Moreover, molecular dynamic computational modeling was performed to understand the molecules optimum coordination, TiO2 geometry, adsorption selectivity, and binary solution adsorption energies. The outcomes of this study will be showcased and discussed in detail.