Hexavalent chromium removal performance of anionic functionalized monolithic polymers: column adsorption, regeneration and modelling

Abstract

Anionic functionalized monolithic macro-porous polymers were used for the removal of hexavalent chromium(VI) anions from aqueous solution in column experiments. At a flux of 1.0 cm min and 30 mg Cr(VI) L-1 feed concentration, breakthrough capacity and apparent capacity were 0.066 g Cr(VI) g(-1) anionic monolith and 0.144 g Cr(VI) g(-1) anionic monolith, respectively. The degree of column utilization was found to lie in the range 41-46%. Two kinetic models, theoretical and Thomas models, were applied to experimental data to predict the breakthrough curves and to determine the characteristic parameters of the column useful for process design. The simulation of the whole breakthrough curve was effective with the models. At a flux of 1.0 cm min and 30 mg Cr(VI) L-1 feed concentration, the dispersion coefficient and adsorption equilibrium constant (K) were 3.14 x 10(-7) m s(-1) and 3,840, respectively. Also, Thomas model parameters k(1) (rate constant of adsorption) and q(m) (equilibrium solid-phase concentration of sorbed solute) were 1.08 x 10(-3) L mg(-1) min(-1) and 0.124 g g(-1), respectively. After reaching equilibrium adsorption capacity, the monoliths were regenerated using 1 N HCl and were subsequently re-tested. It was found that the regeneration efficiency reduced from 98% after second usage to 97% after the third usage.