Effect of particle size on adsorption of heavy metals using chemically modified and unmodified fluted pumpkin and broad-leafed pumpkin pods

Abstract

The effect of particle size on the bioremediation of Pb(II), Zn(II), Cd (II) and Hg(II) ions from synthetic aqueous effluents using unmodified and carboxymethylated fluted pumpkin and broad-leafed pumpkin pods was investigated in a batch system. 1.2 g of adsorbents was used in each sorption experiment at 25 °C and pH 6.5-8.5 for one hour interval. The results showed that the two adsorbents were good for the removal of these metal ions. Unmodified fluted pumpkin pod was found to be better than the other tested adsorbents with removal efficiencies of 92.62%, 81.88%, 75.21% and 49.67% for Pb (II), Zn (II), Cd (II) and Hg (II), respectively. Carboxymethylation decreased the adsorption capacity of the cellulose materials mostly for fluted pumpkin pod. Particle size below 600 μm was found to be the optimum size for unmodified absorbent, while 600-1000 μm was observed for modified adsorbent. Fluted pumpkin pod was found to be a more effective adsorbent for these metal ions than the broad leafed pumpkin pod especially when unmodified. Therefore these results show that fluted pumpkin and broad-leafed pumpkin pods could serve as very good adsorbents in the treatment of these metal ions from aqueous effluents.

Keywords: agricultural waste, bioremediation, heavy metals, pollution control, surface chemistry.