A new Dowex monospher-BBr exchanger was prepared by the reaction between the conjugated base sulfonic acid [R-S-O₃]^- of DOWEX MONOSPHERE MR-450 UPW and the strong Lewis acid BBr₃ forming adduct (coordinated complex) [(R–S-O₃)₂ BBr₃]⁺³. The prepared resin is a promising exchanger for the removal of inorganic arsenic species from underground water. More than 96% arsenic removal has been recorded using the prepared resin. Effect of pH on the sorption of As(III) and As(V) was studied using VISUAL MINTEQ computer program to determine the optimum pH values at which maximum sorption capacities were obtained. The highest sorption efficiency was obtained at pH 11 and 6 for As(III) and As(V), respectively, which indicate good separation between the two different species.Pseudo-first, pseudo-second order, homogeneous particle diffusion models were applied to analyze the experimentally determined data. Sorption data has been modeled using Langmuir and Freundlich sorption isotherm models and the various model parameters were evaluated indicating that chemisorption was the expected controlling process. The applicability of the prepared resin was tested for the removal of arsenic species from real contaminated groundwater. Results gave an evident to the high sorption efficiency of the prepared resin.

Key words: Dowex monospher 450, BBr₃, As(III), As(V), ground water, kinetic and isotherm modelling.