Clint Sutherland, Chintanapalli Venkobachar
Research into the development of cheaper technologies for the interception and treatment of heavymetal-laden waste streams continues unabated. Biosorption using low-cost media provides an attractive alternative. The kinetic manner of a forest product, macro-fungus Fomes fasciatus, was analysed for the selection of an appropriate kinetic model. All experiments were conducted using Cu(II) as a model cation. The kinetic effect of initial Cu(II) concentration and sorbent size was studied in a batch laboratory-scale reactor. Fomes fasciatus exhibited an affinity to Cu(II) ions and approached maximum sorption efficiency as initial concentrations increased beyond 100 mg/l. The sorption process was more complex than that to be scripted by pseudo-first-order kinetics. Pseudo-second-ordern modelling produced a more defined simulation, however, the precision diminished as sorbent size increased. Intraparticle diffusion modelling showed an increasing conformity to increased sorbent size. The mechanisms of biosorption were found to be controlled by film diffusion or combined with surface adsorption during the initial stages. This was followed by a tangled combination of diffusion and chemisorption for the subsequent 98% of the reaction period. A diffusion-chemisorption model was successfully used to simulate the entire period of biosorption kinetics. Additionally, the model produced a good correlation to the reaction variables which not only advanced the development of predictive models involving Fomes fasciatus but can also improve the development of full-scale batch sorption systems.
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