Abstract
The adsorption kinetic experimental data were utilized to capture the intricate relationships behind the mechanism involving the biosorptive capability of a biowaste material to remove toxic substances from an aqueous solution using batch adsorption under specified experimental conditions. Several nonlinear models, such as the pseudo-first order, pseudo-second order, Elovich, intraparticle diffusion, and MacArthur-Wilson were compared. The model parameters were estimated using the Gauss-Newton iterative method of nonlinear regression analysis. Results showed that the removal uptake increases with an increase in adsorbent dose and longer contact time. Removal uptake reflects a relatively slow initial and terminal increase rates against contact time with an overall kinetic process behaving under a pseudo-second order equation. Elovich model suggests higher initial adsorption rate, extent of surface coverage, and activation energy are favored at a lower adsorbent dose, while the intraparticle diffusion is noted to be relatively faster at a higher adsorbent dose. Analysis of the differential forms and the second degree derivatives of the Elovich and MacArthur-Wilson models revealed that it is negative over the entire range of contact time. Error analysis supports that intraparticle diffusion, Elovich, and McArthur-Wilson are possible nonlinear models which can optimally describe the nonlinear behavior of the kinetic processes presented in this study.
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