Removal of Ni (II), Cu (II) and Zn (II) ions from synthetic wastewater using sorghum hulls as adsorbents

Heavy metals are one of the major contaminants from industrial waste water which causes extensive damage to the environment. This study investigated the feasibility of using agro industrial waste sorghum hulls (SH) for adsorption of Ni, Cu, and Zn from simulated effluent. The sorption process was dependent on time, pH and initial metal ion concentration. Sorption process was rapid at initial time and attained equilibrium at about 10 min. Optimum pH for adsorption was found to be 8.0 for Zn (II) and 10.0 for Ni (II) and Cu (II) ions. The sorption process was found to be particle diffusion controlled and of chemisorption mechanism as the pseudo-second order gave a very good fit to the sorption kinetic data. Cu (II) had the highest removal efficiency of 61.23% on 106μm particle size. The sorption trend followed Cu2+>Ni2+> Zn2+. The adsorption equilibrium study showed that the adsorption of the ions was best represented by the Langmuir model for Cu (II) ion, Freundlich model for Ni (II) ion and Temkin model for Zn (II) ion. Therefore, SH and agro waste can be used as an effective adsorbent for the removal of metal ions from industrial effluent.

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