Comparative studies of adsorption of heavy metals from cement waste water using activated carbon from Palm Kernel Husk, coconut and groundnut shells

Abstract

Cement waste water is a major source of heavy metal pollution which requires removal before disposal. This paper therefore evaluates the comparative adsorption of heavy metals from cement waste water using activated carbon from palm kernel husk, coconut and groundnut shells in line with standard methods. With 0.1M KOH as activating agent at 400 oC, PKH and GNS reduced zinc concentration in water from 0.06mg/l to 0.01mg/l while CCS reduced iron concentration by 50% for temperature range of 450 ^oC – 500 ^oC. However, when 0.1M ZnCl was used as activating agent, all three adsorbents reduced the concentration of Zn, Fe and Pb to 0.01mg/l within the temperature range of 400 ^oC – 450 ^oC while Nickel was substantially reduced to 0.01mg/l by all three adsorbents with 0.2M ZnCl as activating agent for temperature range of 400 ^oC to 500 ^oC. The result shows that all three materials could serve as adsorbents but their performance depends on temperature and activating agents. For palm kernel husk and coconut shell, their performance was inversely proportional to temperature, while groundnut shell shows a direct relationship. On the overall, the three precursors showed capacity as good adsorbent for treatment of cement waste- water.

Keywords: Cement, waste- water, activated- carbon, heavy-metals adsorption