The sorption of crude oil using raw (unmodified) and Mn2O3 nanoparticle-modified glycine max husks was investigated for treatment of oil-spilled water surfaces by batch sorption technique. Box-Behnken design was employed for optimization of the sorption process by response surface methodology using design expert software. The sorbents' characterization was by Fourier-transform infrared spectroscopy, scanning electron microscope-energy dispersive X-ray spectroscopy, Brunauer-Emmett-Teller surface area analysis, X-ray diffraction analysis, and Thermogravimetric analysis. Equilibrium isotherm data were evaluated using Langmuir, Freundlich, Temkin, and Scatchard models. The Langmuir gave the best fit to the experimental data and maximum monolayer uptake capacities of 3.47 and 5.29 gg-1 were obtained for the raw and nanoparticle-modified glycine max husks (RGMH and NGMH), respectively. Kinetics showed that their sorption will be satisfactorily described using pseudo-second-order, based on their large R2 values and at equilibrium uptake time of 70 and 50 min for oil onto the RGMH and NGMH, respectively. Thermodynamic parameters revealed a process that is non-spontaneous for RGMH, and spontaneous and feasible for NGMH. Regeneration and reusability after three sets of sorption-desorption were better with NGMH. Thus, Mn2O3 NGMH has greater potential as a sorbent for the management of oil-spilled water surfaces than RGMH.
Keywords: Box-Behnken design; Soybean; crude oil; impregnation; isotherms; kinetics; manganese oxides; pollution; regeneration; sorption.