Hexavalent chromium removal from aqueous solutions by biosorbents (non-living activated sludge)


DESALINATION AND WATER TREATMENT, vol.57, no.40, pp.18688-18693, 2016 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 57 Issue: 40
  • Publication Date: 2016
  • Doi Number: 10.1080/19443994.2015.1091989
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.18688-18693
  • Erciyes University Affiliated: Yes


The removal of hexavalent chromium from aqueous solution was examined by the adsorption process using non-living activated sludge as an absorbent. The kinetics of the hexavalent chromium removal were examined in batch experiments for the concentrations between 1 and 20mg/L hexavalent chromium solutions. The adsorbent dosage applied was 0.1g dry weight of adsorbent/250mL for the non-living activated sludge. Four different mixing times ranging from 30 to 120min and six different pH values between 2 and 7 were assessed to find out the optimum mixing time and pH value. The removal efficiencies were above 56% for all hexavalent chromium concentrations and mixing times. The 250-rpm shaker speed at pH 2 gave the highest removal efficiency. The adsorption kinetics can be described by the pseudo-first-order and pseudo-second-order kinetic models. The rate constants were evaluated for all hexavalent chromium concentrations. This study showed that the hexavalent chromium adsorption kinetics of the non-living activated sludge fitted quite well to the pseudo-second-order kinetic model than the pseudo-first-order kinetic model. This reveals that it is comparative to the square of the concentration of chromium adsorption rate. These results show that non-living activated sludge could be effectively used as a low-cost and alternative absorbent for the removal of hexavalent chromium from aqueous solution.