Camellia oleifera seed shell carbon as an efficient renewable bio-adsorbent for the adsorption removal of hexavalent chromium and methylene blue from aqueous solution

Eco-friendly material from the agricultural or i2ndustrial fiber waste has great potential for the waste water treatment. A low-cost activated carbon from KOH activation of Camellia oleifera seed shell hydrochar was prepared and characterized by SEM, BET, Boehm titration and FT-IR techniques, later used for the adsorption removal of hexavalent chromium (Cr(VI)) and methylene blue (MB). Adsorption kinetic results showed that the adsorption of Cr(VI) and MB fitted better to the pseudo-second-order model (R-2 > 0.99), and the adsorption equilibrium time was 9 h and 3 h, respectively. The maximum adsorption capacity calculated from the Langmuir model results was 307.26 and 493.02 mg g(-1) for Cr(VI) and MB, respectively. pH value had significant effect on Cr(VI) adsorption, but no effect on MB adsorption. Regeneration analysis showed the re-adsorption capacity for Cr (VI) and MB was 165.1 and 278.4 mg g(-1), respectively, following seven cycles of regeneration with water or ethanol. All results demonstrate the high potential of Camellia oleifera seed shell activated carbon in efficient Cr (VI) and MB removal during wastewater treatment. (C) 2017 Published by Elsevier B.V.