This study focuses on evaluating the feasibility of using pore surface diffusion model (PSDM) to successfully predict arsenate breakthrough curves of continuous flow packed columns containing granulated activated carbon modified with iron (hydr)oxide. Two different treatment methods were used to synthesize modified granulated activated carbon media (M-GAC): (i) Fe(III)/alcohol treatment method (M-3-15), and (ii) KMnO4/Fe(II) treatment method (Mn-0.5-15). Adsorption capacities were obtained and fitted by Freundlich isotherm model (q = K x C-E(1/n)) for initial arsenate concentration of 120 g As(V)/L at either pH = 7.3 +/- 0.1 for M-3-15 or pH = 8.3 +/- 0.1 for Mn-0.5-15 in 10 mM NaHCO3 buffered ultrapure water. Short bed adsorber (SBA) columns tests were conducted at the same water quality condition as the batch experiments and used to validate the PSDM.