Preparation And Application Of PGMA-TiO₂-β-CD Composite Adsorbent For Expanded Bed Adsorption

Expanded bed adsorption (EBA) is a novel bioseparation technique, which integrates the clarification, concentration and initial purification into a single step operation unit. It enables the target products to be recovered directly from unclarified feedstock (such as the cultivations of microorganisms or cells and homogenates of disrupted cells) without the prior removal of suspended cells or cell debris. Soy molasses is a byproduct obtained from processing of soybean protein concentrate, which contains soy isoflavone and is always used as livestock feed.The purpose of this study was to develop a PGMA-TiO2composite matrix for EBA, through the method of suspension polymerization. Then, the novel expanded bed adsorbent (PGMA-TiO2-β-CD) was prepared by immobilizing of β-CD onto PGMA-TiO2microspheres, which possess a large amount of glycidyl groups. Finally, the adsorbent was used to recover soy isoflavones from unclarified soy molasses.The thesis is divided into three sections. The preparation of the PGMA-TiO2composite matrix had been gained successfully. The optimal preparing conditions were found to be as follows:the mass ratio of oil phase to water phase at3:1, the concentration of the initiator at0.7%, the concentration of crosslinking agent at38%, the mixing speed at300-400r/min. Under these conditions, the effects of TiO2powder contents on the physical properties of PGMA-TiO2matrix were studied. The results showed that the matrix have regular sphericity, good properties and size distributions, which are similar to the commercial Streamline matrix.The novel expanded bed adsorbent (PGMA-TiO2-β-CD) was prepared by immobilizing of β-CD onto PGMA-TiO2microspheres. The optimal reaction conditions were found to be as follows:the mass ratio of β-CD to PGMA-TiO2microsphere at1:1, the reactive temperature and time at70℃and19hours. The PGMA-TiO2-β-CD adsorbent was characterized by infrared spectra analysis (IR) and scanning electron microscopy (SEM). Under these experiment conditions, the flow in expanded bed was proved to be plug flow for the composite matrices prepared. The custom-made adsorbent (PGMA-TiO2-β-CD) was introduced to recover from unclarified soy molasses, which was found that the total recovery was up to91%. The purity of soy isoflavone gained was about78.6%. Compared with the traditional purification processes, the EBA saved lots of operation time and costs, adequately exhibiting its high efficency and integrality.