International Journal of Chemical Studies
Vol. 5, Issue 2 (2017)
The kinetics of sorption of Cd (ll), Co (ll) and Cr (lll) ions from aqueous solution using Orchid Malabar (Piliostigma malabaricum) Seed pod
Author(s): FK Ekuma, KO Amadi and J Nwogu
Abstract: Increased industrial activities have led to the generation of large amounts of wastewater polluted with heavy metals. Adsorption is recognized as one of the effective and economic methods for removal of low concentration of heavy metal ions from aqueous solution and industrial wastewater. In the present study, an agro-based adsorbent, orchid malabar seed pod was employed in the removal of Cr(lll), Co(ll) and Cd(ll) ions from aqueous solution. The batch adsorption study was performed as a function of adsorbent dose and contact time. The dynamics of the process was investigated in order to establish the exact kinetics of the process and the likely mode of bonding of the metal ions to the adsorbent binding sites. Results obtained showed that optimum contact time of two hours was sufficient for the attainment of equilibrium for the adsorption process. The experimental adsorption data were analyzed using four sorption kinetic models viz; pseudo first-order, pseudo second-order, Elovich and intraparticle diffusivity models. Results obtained showed that the pseudo second-order gave the best description to the experimental adsorption data with correlation coefficients (R2 values) ranging from 0.971 to 0.979 for the three metal ions. The calculated pseudo second-order kinetic rate constants k2 (g.mg-1min-1) obtained from the plots gave 0.003, 0.011 and 0.011 for Cd(II), Cr(III) and Co(II) ions respectively. The calculated equilibrium sorption capacities, qe for the three metal ions were found to agree very closely with experimentally determined values and are listed as 10.42 mg/g, 11.49 mg/g and 10.42 mg/g respectively for Cr(IlI), Cd(II) and Co(II) ions indicating that Cd(ll) was best adsorbed among the three metal ions. Kinetic studies also show that the adsorption transport mechanism follows film-diffusion.
Pages: 378-383 | 571 Views 14 Downloads
How to cite this article:
FK Ekuma, KO Amadi, J Nwogu. The kinetics of sorption of Cd (ll), Co (ll) and Cr (lll) ions from aqueous solution using Orchid Malabar (Piliostigma malabaricum) Seed pod. Int J Chem Stud 2017;5(2):378-383.