A diffusion-chemisorption kinetic model for simulating biosorption using forest macro-fungus, fomes fasciatus.pdf

<div> <div> <div> <p>Research into the development of cheaper technologies for the interception and treatment of heavy- metal-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-order 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. </p> </div> </div> </div

Equilibrium Modeling of Cu(II) Biosorption onto Untreated and Treated Forest Macro-Fungus Fomes fasciatus

<div> <div> <div> <div> <p>Discharge of heavy metal laden wastewaters into the aquatic environment continues to inspire research into the development of low-cost treatment technologies. The identification of low-cost biosorbents and their subsequent optimization particularly through surface modification has been reported to improve the efficiency of biosorption process. This study investigates the biosorptive performance of treated and untreated forest macro-fungus Fomes fasciatus for the uptake of Cu (II) ions (a model cation) from aqueous solution. Batch equilibrium experiments at room temperature were conducted to assess removal as a function of solution concentration and biosorbent mass. An improvement of 17.5 per cent increase in sorption capacity as well as an accompanying increase in affinity was observed as a result of hot-alkali treatment of the biosorbent. Primary equilibrium data was analyzed by linear and non-linear regression using the Langmuir and Freundlich two-parameter models as well as the Redlich-Peterson and Sips three- parameter models. The goodness of fit was assessed using the coefficient of determination, r2, the Relative Percent Error, RPE, Marquardt’s Percent Standard Deviation, MPSD and Hybrid Error Function, HYBRID. The two-parameter Langmuir model exhibited a high correlation to the experimental data and was successful in providing some insight into the biosorptive process. The three-parameter models produced the highest correlation to the equilibrium data, sufficient to enable the future development of predictive models. </p> </div> </div> </div> </div