Abstract

INYINBOR, Adejumoke A.; ADEKOLA, Folahan A.  and  OLATUNJI, Gabriel A.. Adsorption of Rhodamine B dye from aqueous solution on Irvingia gabonensis biomass: Kinetics and thermodynamics studies. S.Afr.j.chem. (Online) [online]. 2015, vol.68, pp.115-125. ISSN 1996-840X.  http://dx.doi.org/10.17159/0379-4350/2015/V68A17.

Raw Irvingia gabonenses (dika nut) (DN) and its acid-treated form (ADN) were used for the uptake of rhodamine B (RhB) dye from aqueous solution. The adsorbents were characterized by Fourier transform infrared (FTIR) spectroscopy, Brunauer-Emmett-Teller (BET) surface area analysis and scanning electron microscopy (SEM). The adsorbents were found to have characteristic functional groups such as -OH, C-N and C=O. SEM revealed that acid treatment resulted in the development of several pore sizes. Sorption data fitted the Freundlich adsorption isotherm better than the Langmuir isotherm. The maximum sorption capacities, q_max, obtained from the Langmuir adsorption isotherm were 212.77 and 232 mg g^-1 for DN and ADN, respectively. The pseudo-second-order kinetics model was observed to fit the adsorption data. Solution pH and temperature significantly influenced the adsorption process and negative values of DG° suggest that the sorption process was spontaneous and feasible. Intraparticle diffusion mainly controlled the uptake of RhB onto DN and ADN; however, boundary layer diffusion also occurred in the RhB-ADN system. The desorption efficiency of RhB from the adsorbents was tested with a number of eluents. The eluents were found to follow the order: H₂O>CH₃COOH>HCl and CH₃COOH>HCl>H₂O for DN and ADN, respectively.

Keywords : Irvingia gabonenses; adsorption; rhodamine B; thermodynamics; kinetics; biomass.

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