Sorption of heavy metals from electroplating effluents by low-cost adsorbents II: Use of waste tea, coconut shell and coconut husk

Abstract

Present research focuses on the use of waste tea, coconut shell and coconut husk as potential low-cost adsorbents for removal of heavy metals chromium (Cr), zinc (Zn) and nickel (Ni)) from three different electroplating plant effluents. The traditional activated carbon was also compared for objective assessment of the efficiency of the low cost adsorbents. The adsorbents were used in batch tests with electroplating effluents, its metal binding capacity, pH dependence of metal uptake and kinetics of metal adsorption were investigated. The study showed most of the metal uptake was within the first 60 min of exposure for all the adsorbents. Cr (VI) was optimally bound to the adsorbents at pH 3-4 and Zn(II) and Ni(II) at pH 7-9. The metal binding capacity differed for the adsorbents. Coconut shell was more effective for Ni (97.36% removal). All the three showed high rate of adsorption Zn (coconut shell, 99.74%, coconut husk 99.76% and waste tea 90.74% removal). All three satisfied the Freundlich Adsorption Isotherm. © 2007 Asian Network for Scientific Information.