Abstract

NABIZADEH, R.; JAHANGIRI-RAD, M.  and  SADJADI, S.. Modelling the effects of competing anions on fluoride removal by functionalized polyacrylonitrile coated with iron oxide nanoparticles. S.Afr.j.chem. (Online) [online]. 2015, vol.68, pp.201-207. ISSN 1996-840X.  http://dx.doi.org/10.17159/0379-4350/2015/v68a27.

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 CO₃^2-> PO₄^3- > SO₄^2- > Cl^-. The presence of anions at various concentrations decreased fluoride adsorption capacity on PAN-oxime-nano Fe₂O₃ by 1.22 to 6.51 mg g^-1. 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.

Keywords : Fluoride; PAN-oxime- nano Fe₂O₃; counterion; adsorption.

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