Anodic surface treatment on activated carbons for removal of chromium(VI)

In this work, the effect of anodic surface treatment on activated carbons and its Cr(VI) adsorption properties were investigated under reaction-treatment time conditions with 35 wt% HCl solution. The acid-base surface values were determined by Boehm's titration technique. The pore and surface characteristics were studied in terms of BET volumetric measurement with N₂ adsorption. As an experimental result, the acidic surface functional groups of activated carbons increased with increasing the HCl reaction-treatment time. It was found that the surface characteristics, including specific surface area, total pore volume, net heat of adsorption, and BET's C, slightly decrease in anodic surface treatments on activated carbons. In addition, an increase in reaction-treatment time led to increases of the first rate (K₁) of Cr(VI) adsorption and diffusion coefficient (D). These values are evidence that adsorption is controlled more by the acid-base interactions between electron-donor substances and acidized activated carbons as electron acceptor than by the pore and surface structures of activated carbons.