The performance evaluation of TiO2 nanoparticles in the removal of chromium from aqueous solutions: adsorbent characteristics and isotherm study

Chromium (Cr), as a metallic pollutant, enters to the body through drinking water. Due to the toxic and dangerous characteristic of hexavalent chromium, its removal is necessary. In this research, titanium dioxide nanoparticles were used as an adsorbents to remove Cr from water. The characteristic of TiO2 nanoparticles were determined using XRD and FTIR analyses. Batch adsorption experiments were performed using synthetic aqueous solutions containing chromium. The optimal conditions of adsorption were investigated at various pHs, initial concentration of metal ion, contact time and the adsorbent dosage on Cr adsorption capacity. Also, the study was carried out ethically and there was no bias and confinement on the part of the researcher during the research process. The results showed that the removal percentage at pH=3 (88.50%) was significantly more than the other studied pHs. The lowest removal percentage was observed at pH = 9 (38.03%). at the highest Cr adsorption was noticed in concentration of 0.5 g/L (61.52%), which was statistically significant as compared to other concentrations Accordingly, the lowest adsorption was observed at 5 g / L concentration (6.75%). Adsorption performance was not significantly different at different times, and the amount of adsorption was almost constant after 30 minutes. Cr adsorption by TiO2 nanoparticles increased with increase in adsorbent dose and the maximum amount of adsorption occurred at 4 g/L (68.31%) which again was significantly higher than other studied dosages. The lowest removal percentage was observed at 1 g/L (18.57%). The sorption isotherm studies showed that adsorption of chromium by titanium dioxide was fitted well to Freundlich isotherm model (R2 = 0.78). Titanium dioxide demonstrate high efficiency in adsorbing chromium from wastewater and thus can be a promising sorbent for the treatment of industrial wastewaters