Modelling the Effects of Competing Anions on Fluoride Removal by Functionalized Polyacrylonitrile Coated with Iron Oxide Nanoparticles

Fe2O3 nano particles supported on functionalized poly-acrylonitrile was prepared. PAN-oxime-nano Fe2O3 was characterized by XRD, FTIR and TEM and used for fluoride adsorption. The adsorption capacity increased with increasing initial fluoride concentration and reaction time. Fluoride-removal performance of PAN-oxime-nano Fe2O3 was also tested in the presence of various competing anions usually found in drinking water. Competitive sorption between fluoride and competing anions showed a minimum preference for chloride counterions. Carbonate was the greatest competitor for fluoride removal followed by phosphate and sulphate. Counterion presence decreased fluoride adsorption capacity in order of CO PO SO Cl 3 2 4 3 4 2 − − − − > > > . The presence of anions at various concentrations decreased fluoride adsorption capacity on PAN-oxime-nano Fe2O3 by 1.22 to 6.51 mg g. Effects of each two anions exist simultaneously in aqueous solution on fluoride adsorption was investigated using Tukey’s test (called also a pairwise comparison). Tukey’s HSD results indicate that the differences between various pairs of anions are significant (P < 0.05), except for chloride–sulphate (P = 0.08). In the design of PAN-oxime-nano Fe2O3 for environmental applications, the strong influence of the counter ions must be considered.