The immobilization of Pseudomonas delafieldii R-8 in calcium alginate beads has been studied in order to improve biodesulfurization activity in oil/water (O/W) biphasic systems. A gas jet extrusion technique was performed to produce immobilized beads. The specific desulfurization rate of 1.5 mm diameter beads was 1.4-fold higher than that of 4.0 mm. Some nonionic surfactants can significantly increase the activity of immobilized cells. The desulfurization rate with the addition of 0.5% Span 80 increased 1.8-fold compared with that of the untreated beads. The rate of biodesulfurization was markedly enhanced by decreasing the size of alginate beads and adding the surfactant Span 80, most likely resulting from the increasing mass transfer of substrate to gel matrix.
The objective of this study was to investigate the potential for Penicillium sp. QQ to perform copper adsorption. The following optimal conditions were assigned for biosorption by a response surface methodology (RSM): a biomass concentration of 4.6% (w/v), pH of 5.6, initial copper concentration of 100 mg/L and an established biosorption equilibrium after a 30 min reaction. A copper removal efficiency of about 98% was achieved after 30 min. The kinetics of copper adsorption are discussed, and the experimental data are fit to a pseudo-second-order kinetic model. The experimental results were analyzed using the Langmuir and Freundlich isotherms. The equilibrium constant b and n value show copper has been favorably adsorbed by the QQ strain. The thermodynamic parameters such as the free energy (∆G o ), enthalpy (∆H o ) and entropy (∆S o ) also prove the adsorption process was thermodynamically feasible and spontaneous. The results indicate Penicillium sp. QQ could be used as a promising candidate for removing heavy metal ions from aqueous environments.
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