Removal of Fluoride Ion from Aqueous Solution by Nanocomposite Hydrogel Based on Starch/Sodium Acrylate/Nano Aluminum Oxide

Determination of fluoride in drinking water has received increasing interest، due to its beneficial and detrimental effects on health. Contamination of drinking water by fluoride can cause potential hazards to human health. In recent years، considerable attention has been given to different methods for the removal of fluoride from drinking and waste waters. The aim of this research was to investigate the effect of nano composite hydrogel based on starch/sodium acrylate/aluminum oxide in reduction of fluoride concentration in drinking water and industrial waste water. In a batch system، the dynamic and equilibrium adsorption of fluoride ions were studied with respect to changes in determining parameters such as pH، contact time، initial fluoride concentration، starch/acrylic acid weight ratio and weight percent of nano aluminum oxide. The obtained equilibrium adsorption data were fitted with Langmuir and Freundlich models، as well as the kinetic data with pseudo-first order and pseudo- second order models. The results showed that optimum pH was found to be in the range of 5 to 7. Removal efficiency of fluoride was increased with decreases in initial concentration of fluoride. Sixty percent of initial value of fluoride solution was removed by nano composite hydrogel (4 wt% of nano aluminum oxide) at 240 min (initial fluoride concentration = 5 ppm، pH 6. 8 and temperature = 25ºC). Under the same condition، the equilibrium adsorption of fluoride ions was 85% and 68% for initial solution concentration of 5 and 10 ppm، respectively. Adsorption isotherm data showed that the fluoride sorption followed the Langmuir model. Kinetics of sorption of fluoride onto nano composite hydrogel was described by pseudo-first order model.