Comparative evaluation of commercial and natural nanoparticle adsorbents for efficient arsenic removal: Insights from kinetic modeling

Arsenic, which is a toxic substance in the human body, has attracted great interest due to high levels in drinking water supplied from underground resources. Novel separation methods for arsenic removal perform innovative products developed using nanomaterials. In this study, batch experiments were conducted for Adsorbsia GTO to obtain kinetics and mechanisms of As(V) sorption, and then they were compared to commercially available adsorbent MTM® and natural minerals named hematite (Fe2O3), goethite (FeOOH), and manganese dioxide (MnO2). Adsorbsia GTO fitted slightly better to the Freundlich Isotherm with high adsorption capacity of 27.25 mg/g at pH 4. MnO2 fitted to the Langmuir Isotherm very well and resulted in the highest adsorption capacity of 0.72 mg/g in natural oxides. The kinetics of all materials were modeled with "Infinite Solution Volume" and "Unreacted Core" models to understand reaction kinetics. Adsorbsia GTO fitted to models of "liquid film diffusion" and "chemical reaction" with over 0.98 of R2 value. Column studies showed that Adsorbsia GTO had breakthrough and total exchange capacities of 26.5 and 84.4 mg/ml, respectively. As a natural alternative, MnO2 with breakthrough and total exchange capacities of 4.3 and 14.2 mg/ml, fitted the models of "particle diffusion" and "reacted layer" in natural minerals.