Cr(VI) tolerance in Aspergillus flavus, strain SFL, isolated from tannery effluent was measured and compared with a reference strain of A. flavus, A1120. On solid medium, SFL had a high level of ...Cr(VI) tolerance (1,600 mg/L), which was 16 times that of A1120 and greater than most previously analyzed fungal strains. When in 100 mg/L of Cr(VI), SFL completely depleted Cr(VI) within 72 h while A1120 depleted 85% of Cr(VI). SFL was more effective in reducing extracellular Cr(VI) than A1120. While A1120 showed greater biosorption of Cr(VI) than SFL, intracellular accumulation was approximately 50% greater in SFL and was more energy‐dependent than A1120. Cr(VI) modified the external surface of the hyphae. Cr speciation detected the presence of only Cr(III), corresponding to Cr(OH)3, which precipitated on the hyphal surface. Cr(VI) bound to the functional groups carboxyl, amine, and hydroxyl in both SFL and A1120. Transmission electron microscopy energy‐dispersive X‐ray detected Cr on the fungal wall and within membrane‐bound organelles of the cytoplasm. In conclusion, the greater tolerance of SFL to Cr(VI) relative to A1120 is due to more effective energy‐dependant uptake of Cr(VI) into the cell and increased capacity of SFL to store Cr in intracellular vacuoles compared with A1120.
The kinetics study of steam reforming of ethanol was done using Co/Al
2O
3 catalysts to investigate the effect of reaction temperature, contact-time and steam to ethanol molar ratio on hydrogen ...production. Co/Al
2O
3 catalysts, prepared by wet impregnation method, were characterized for their surface area, pore volume, pore size and X-ray diffraction pattern. All the experiments were carried out in a fixed-bed tubular reactor. Surface reaction mechanism has been proposed based on the literature and product distribution obtained in the present study. The mechanistic kinetic model using Langmuir–Hinshelwood (L–H) approach was developed considering surface reaction mechanisms of steam reforming of ethanol, water gas shift and ethanol decomposition reactions. The kinetic parameters of the multi-response non-linear mechanistic kinetic model were estimated using a non-linear least-square regression by fitting the expression to the experimental data. A reasonably good fit of the data indicates that the formation of acetaldehyde from ethoxy is the rate-determining step (RDS) for reforming reaction. The kinetic model is able to describe the steam reforming of ethanol process adequately for a wide range of experimental data.
