Removal of Thallium from Aqueous Solutions by Adsorption onto Alumina Nanoparticles

Thallium (I) was removed from aqueous solution by using gamma-alumina nanoparticles (gamma ANPs) materials as nano adsorbents. Varied experimental conditions such as adsorbent dose, agitation time, initial concentration, pH, and temperature effects were carried out in batch conditions in view of the optimization of thallium (I) adsorption and the identification of the adsorption mechanisms in the system gamma ANPs-Tl. The pH effect indicated a remarkable increase in the quantity of Tl(I) removed for pH values ranging from 4 to 8, an almost constant magnitude for pH values between 8 and 10, and a decrease for pH values above 10. Considering an initial Tl(I) concentration of 20 mu g/L and an adsorbent dose of 1 g/L at a pH value of 8.5, the removal was achieved at 95.12 +/- 0.02% efficiency. The pseudo-second-order kinetics and the Freundlich isotherm perfectly described the adsorption mechanism. The process of thallium (I) adsorption reaction, as highlighted by thermodynamic investigations, was found to be spontaneous and exothermic with coexistence of physisorption and chemisorption with a dominance of physisorption. The diffusion model predicted multi-linearity, suggesting an involvement of surface spread and intraparticle diffusion in the sorption process. Thallium removal was effective by using gamma ANPs as nano adsorbents.

Automated summary

Thallium (I) was efficiently removed from aqueous solution using gamma-alumina nanoparticles as nano adsorbents. The adsorption process was optimized by varying experimental conditions such as adsorbent dose, agitation time, initial concentration, pH, and temperature. The results showed that the removal efficiency was highest at pH around 8, and the adsorption mechanism followed pseudo-second-order kinetics and Freundlich isotherm. Thermodynamic investigations revealed that the adsorption was spontaneous and exothermic, with physisorption dominating. The diffusion model suggested the involvement of both surface spread and intraparticle diffusion in the sorption process.