Regeneration of As(V) loaded granular activated carbon through desorption in FeCl₃, CaCl₂ and MgCl₂ aqueous solutions

As(V) adsorption on granular activated carbon (GAC) and subsequent desorption in dH₂O was modeled using the pseudo-first and pseudo-second order kinetic models. Regeneration was achieved by immersing loaded GAC in NaCl, FeCl₃, CaCl₂ and MgCl₂ aqueous solutions. As(V) detection after desorption was highest for NaCl but subsequent adsorption was lowest. Regeneration was highest in FeCl₃ solution of pH 2 followed closely by pH 3, but As(V) precipitation appeared superior at pH 3. Molar ratios of Fe, Ca and Mg to As were tested in the range of 0.75:1 to 12:1 where a logarithmic relation was found between the molar ratio and As(V) desorption as diluted in HNO₃ and H₂O and subsequent adsorption. Precipitation was nearly complete in FeCl₃, limited in MgCl₂ at a ratio of 12:1 and not observed in CaCl₂. While kinetic values were lower than in previous tests, the pseudo-first and pseudo-second order models could accurately describe desorption in CaCl₂ and MgCl₂ but not in FeCl₃ due to precipitation. Desorption in FeCl₃ was most effective in precipitating As(V), being highest at a molar ratio of 6:1, but regeneration was slightly higher at a molar ratio of 12:1.