Microbial cells of

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Conclusions:The cells immobilized in magnetic PVA beads could be stably stored and be repeatedly used over 12 times for biodesulfurization. The immobilized cells could be easily separated by magnetic field. Significance and Impact of the Study: Magnetic PVA beads are easy to prepare. The immobilization process in the paper is to increase the efficiency of cells and to decrease the cost of operations.

To improve biodesulfurization rate is a key to industrialize biodesulfurization technology. The biodesulfurization rate is partially affected by transfer rate of substrates from organic phase to microbial cell. In this study, gamma-Al2O3 nanosorbents, which had the ability to selectively adsorb dibenzothiophene (DBT) from organic phase, were assembled on the surfaces of Pseudomonas delafieldii R-8 cell, a desulfurization strain. gamma-Al2O3 nanosorbents have the ability to adsorb DBT from oil phase, and the rate of adsorption was far higher than that of biodesulfurization. Thus, DBT can be quickly transferred to the biocatalyst surface where nanosorbents were located, which quickened DBT transfer from organic phase to biocatalyst surface and resulted in the increase of biodesulfurization rate. The desulfurization rate of the cells assembled with nanosorbents was approximately twofold higher than that of original cells. The cells assembled with nanosorbents were observed by a transmission electron microscope.

Magnetic alumina sorbent was used in the separation of aromatic compounds from gasoline by a π-complexation mechanism. Magnetic alumina sorbents can effectively adsorb polycyclic aromatics and polycyclic aromatic sulfur compounds from model gasoline, and the amounts adsorbed were up to 0.12 mmol‚(g of sorbent) -1 . The interactions between various aromatics and sorbents of different acidities were studied. The results showed that the amounts adsorbed are related to the capability of forming π-complexation interactions, and the magnetic alumina sorbent used was found to have the following order of adsorptive ability for aromatics: pyrene > naphthalene > DBT ≈ fluorene. Al 3+ and its oxide are Lewis π-acids, and aromatic compounds are Lewis π-bases; thus, they can form π-complexes with each other. The π-complexation was verified by fluorescence spectrum. The quenching of the fluorescence of pyrene by Al 3+ was due to partial π-electron transfer from pyrene to the cation according to Lewis theory and fluorescence quenching theory.

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