| 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.The specially-designed matrix is the principal "hardware" pillar supporting the successful application of expanded bed adsorption. In this work, a new type of composite matrix was prepared with cellulose as the framework and stainless steel powder as the inert weighted through the water-in-oil suspension thermal regeneration method. Then, the physical properties and expansion characteristics of cellulose/stainless steel powder composite matrix were investigated systematically. Finally, a dye-affinity expanded bed adsorbent based on the cellulose/stainless steel powder composite matrix was developed, and its adsorption properties and application in expanded bed were studied subsequently.The thesis is divided into five sections. Section 1 is the review of expanded bed adsorption, including the history, principles and operation modes. The advances in the matrices of expanded bed adsorption are introduced with the emphasis on the physicochemical properties required, familiar types as well as their preparation methods. Furthermore, on the base of physical properties, preparation methods and applications of cellulose matrix, the idea is put forward, which adopted the composite of regenerated cellulose and stainless steel powder to prepare a novel hydrophilic porous matrix for expanded bed adsorption through the water-in-oil suspension thermal regeneration method.Section 2 summarizes a series of methods for the analysis and characterization of the composite matrix and dye-affinity adsorbent, including basic physical properties, pore structures, instrument analysis, expansion characteristics and adsorption abilities. The application potential of the prepared matrix can be estimated through these methods mentioned above.Section 3 studies the preparation of the composite matrix. The optimal reaction conditions were found to be as follows: the ageing temperature and time at 15 ℃ and 24 hours, the xanthation temperature and time at 30 ℃ and 3 hours, the mass ratio of disperse phase to water phase at 6:1 and the mixing speed at 500-600 rpm. Under these conditions, the effects of stainless steel powder contents on the physicalproperties and pore structures of two matrices containing different size distribution were studied. The results showed that both matrices have regular sphericity, good properties, pore structures and size distributions, which are similar to the commercial Streamline matrix.Section 4 investigates the expansion characteristics of the matrices prepared. The results indicated that the expansion behavior of both matrices agreed well with the Richardson-Zaki law and the relationship of expansion factor E and flow velocity U could be described. The liquid mixing performances in the bed were studied through retention time distribution (RTD) test, which showed that the flow velocity was an important parameter effecting on the stability of expanded bed. The increase of flow velocity would increase the degree of the axial mixing in the bed. Under these experiment conditions, the flow in expanded bed was proved to be plug flow for the composite matrices prepared.Section 5 involves the preparation and adsorbability of dye-affinity adsorbent based on the cellulose/stainless steel powder composite matrix. The optimized reaction conditions were found to be as follows: the cellulose content in viscose at 8 wt%, the mass ratio of stainless steel powder and viscose at 1:4, the size distribution of composite matrix at 60~150 (im and the initial concentration of dye solution at 20 mg/mL The lactate dehydrogenase (LDH) adsorption isotherms of the prepared dye-affinity adsorbent followed the Langmuir adsorption equation and the a... |
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