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

T.C. Prathna, S. Kumar Sharma, M. Kennedy
UNESCO-IHE,
Netherlands

Keywords: iron oxide, alumina, nanoparticles, adsorption, arsenic, fluoride

Summary:

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 point of zero charge around pH ~6.5 as determined by zeta potential analysis. The size and morphology of the particles were determined by Scanning Electron Microscopy which revealed polydisperse particles with a size range between ~250-500 nm. EDAX analysis confirmed the presence of Al, Fe and O elemental peaks in the samples. 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 arsenic and fluoride removal potential. Increase in the weight of iron oxide nanoparticles (from 0.05 g to 0.2 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. The As (V) removal capacity (460 µg/g) was significantly higher than As (III) removal (226 µg/g). Increase in the duration of calcination at 550 ºC from 1h to 3h led to a corresponding increase in the average particle size from 219 ± 13.31 nm to 273 ± 19.49 nm. However, the fluoride removal capacity was not affected with changes in the duration of calcination. Increase in the duration of calcination from 1h to 3h did not affect the As (V) removal capacity, however, a decreasing trend in As (III) removal was observed (from 250 µg/g to 95 µg/g). The results demonstrated that that 0.05 g of iron oxide nanoparticles added during synthesis and calcination of the composites at 550 ºC/1h was sufficient for optimum As and F removal. The preliminary results of the study showed that the synthesized nanocomposites can be promising adsorbents for both As and F removal in small scale water systems.