A comparison study of peach stone and acrylonitrile-divinylbenzene copolymer based activated carbons as chromium(VI) sorbents

Two activated carbons were produced by using two different precursor; peach stone and acrylonitrile-divinylbenzene copolymer. Peach stone based activated carbon was produced by single step steam activation at 800 °C, polymer based activated carbon was prepared in successive two stages; air oxidation at 300 °C and final carbonization at 850 °C under inert atmosphere. Produced carbons showed typical Type 1 nitrogen adsorption isotherms. Peach stone based activated carbon has 608 m2/g of surface area and 0.331 cm3/g of micropore volume, while polymer based carbon has 579 m2/g of surface area and 0.234 cm3/g of micropore volume. Boehm's titration results and Fourier transform infrared spectra indicated that the produced carbons possess acidic oxygen functionalities mainly in phenolic form. Polymer based activated carbon has 7.12 mmol of nitrogen/g because of the pyridine type groups in the main structure. The removal of Cr(VI) from aqueous solutions by activated carbon has been investigated as a function of solution pH. The maximum adsorption capacities were obtained at pH 2 in both cases and the maximum capacities were 143 mg/g, 83 mg/g and 150 mg/g for peach stone based, polymer based and commercial activated carbons, respectively.The produced carbons could be regarded as potential adsorbents for efficient removal of Cr(VI) from aqueous media.