Sorption Kinetic and Intraparticle Diffusivities of As 3+ and Hg 2+ Detoxification from Aqueous Solution Using Cellulosic Biosorbent Derived from Okra (Abelmoschus esculentus) Stems

O. K. Amadi (1) , C.J. Odidiozor (1) , I.A. Okoro (1)

1 MOUAU - Michael Okpara University of Agriculture

The use of biodegradable, renewable and readily available local materials like cellulosic biosorbent produced from Okra stems as biosobent for the removal of toxic metal ions As(III) and Hg(II) ions were investigated and the results of the studies modeled using conventional adsorption models. The batch sorption study was performed as a function of pH, particle size and contact time. The dynamics of the process was investigated in order to establish the exact kinetics of the process and likely mode of bonding of the metal ions to the adsorbent binding sites.The results obtained indicates that optimum contact time of 120 min was sufficient for the attainment of of equilibrium for the sorption process. The experimental sorption data were analyzed using three sorption kinetic models viz; pseudo first-order, pseudo second-order and intra-particle diffusivity models. Results obtained showed that the pseudo second-order gave the best description to the experimental sorption data with correlation coefficients (R 2 values) of 1 and 0.999 for both unmodified and modified Okra stem for the two metal ions. The calculated pseudo second-order rate constants k 2 (g.mg-1 min-1) obtained from the plots gave 10, 0.0636 and 10, 0.0335 for unmodified and modified Okra stems for Hg(II) and As(III) ions respectively. The calculated equilibrium sorption capacities, qe for unmodified and modified adsorbent were found to agree closely with experimentally determined values and are the same 10, 10.101 for the two metal ions. The result also showed in percent mean value of sorption for As 3+ and Hg 2+ as 99.37 % and 99.96 % for neat Okra cellulosic biosorbent, and 99.95 % and 99.96 % for modified Okra cellulosic biosorbent. These results showed that the neat material can be effective without introducing any new chemical substances to the environment through the modification exercise. The mechanism of sorption tested showed a film diffusion models. The sorption affinity for the two metal ions studied showed As(III) > Hg(II).

Mots clés: Okra cellulosic material; sorption; biosorbent; As 3+; Hg 2+; sorption model

Domaines: Polymères; Ingénierie de l'environnement

O. K. Amadi, C.J. Odidiozor, I.A. Okoro. Sorption Kinetic and Intraparticle Diffusivities of As 3+ and Hg 2+ Detoxification from Aqueous Solution Using Cellulosic Biosorbent Derived from Okra (Abelmoschus esculentus) Stems. International Journal of Engineering and Information Systems, 2017, 1 (8), pp.72-85. ⟨hal-01648442⟩