Abstract: Two raw materials were investigated to provide a cheap and efficient arsenic removal from drinking water supply. For this purpose, studied materials were modified by insertion of iron within the materials' structure and substitution of calcium and magnesium ions with sodium ions in order to improve the sorptive and ion-exchange properties. White tuff from Strmos region and the commercially available Zeofit were the materials considered within our study. Simulations were performed on

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... were performed on prepared solutions of arsenic added to water samples from the water supply in Skopje. Obtained results suggest that the Zeofit material produced better results regarding arsenic adsorption at various initial arsenic concentrations. The white tuff from Strmos is effective only at lower initial concentrations of arsenic. Regarding the equilibrium study on investigated systems for both materials, implemented models produced a good fit when applied to As5+ systems. The Strmos material did not produce satisfactory fitting results to implemented equilibrium models for the As3+ systems.