Development of alumina/iron oxide nanocomposites as adsorbents for arsenic and fluoride removal from aqueous solutions: Process optimization

The study was designed to optimize the process for the synthesis of alumina/iron oxide nanocomposites and to investigate their potential as a sorbent to remove fluoride and arsenic from contaminated water. The nanocomposites had a size range between ∼250-500 nm. Process variables such as the weight of iron oxide nanoparticles added during the course of synthesis of the nanocomposites and the duration of calcination were studied as a function of particle size and As and F removal potential. Increase in the weight of iron oxide nanoparticles (from 0.05 g to 0.1 g) added during the course of synthesis did not lead to a significant change in the particle size measurements nor did it increase the As and F removal capacity. Increase in the duration of calcination at 550 °C led to a corresponding increase in the particle size from 219 ± 13.31 nm to 273 ± 19.49 nm. The sorption data for As (III), As (V) fitted best to Freundlich isotherm while for F it fitted the Langmuir isotherm. Increase in the duration of calcination from lh to 3h showed increased q_m values for As (V) and F. The results demonstrated that 0.05 g of iron oxide nanoparticles added during synthesis and calcination of the composites at 550 °C/3h was sufficient for optimum As and F removal.