ABSTRACT
34The use of agricultural wastes (groundnut shell, orange peel and rice husk) as potential cost-effective adsorbent for heavy metal removal from wastewater was evaluated. The effect of pH (2.0 – 6.0), adsorbent dosage (0.6 – 2.2 g), contact time (10 – 130 min) and initial concentration (Pb: 5 – 105 mg/L, Cu and Zn: 2.5 – 52.7 mg/L) on metal removal efficiency and uptake capacity were investigated using response surface methodology to optimize the process conditions. Groundnut shell showed a high potential to remove Cu, Pb and Zn from synthetic wastewater. The optimum conditions obtained were: 2.5 g adsorbent with 40.7 mg/L Cu at pH 4.4 and 64 min, 2.5 g adsorbent with 196.1 mg/L Pb at pH 5.6 and 60 min contact time, and 3.1 g adsorbent with 70.2 mg/L Zn at pH 4.3 and 50 min, for Cu, Pb and Zn, respectively. The regeneration of the groundnut shell was possible for a maximum of 3 cycles using 0.2 M HCl as the desorbing solution without any significant change in the adsorbing efficiency.
