Preparation Of Cellulose/Tungsten Carbide Powder Composite Adsorbent For Expanded Bed Adsorption By NMMO Process

Expanded bed adsorption (EBA) is a novel bioseparation technique, which integrates the collection of goal product, clarification, concentration and initial purification into a single step operation unit. And this technique be doomed to develop greatly in future. The specially-designed matrix is the principal "hardware" pillar supporting the successful application of expanded bed adsorption. The basic criteria of the matrices for EBA are formulated as being a sufficiently high density ,an appropriate size distribution and good globularity.The point of this article is to prepare a new type of composite matrix with cellulose as the framework and tungsten carbide powder as the inert weighted through the sequential cooling reversed phase suspension technique. The innovation of this work is the application of novel solvent of cellulose—NMMO.First of all, this article studies the preparation of the composite matrix. The optimal reaction conditions were found to be as follows: cellulose concentration 4%, dispersant Tween80 2%, and the mixing speed at 900 rpm. Under these conditions, the effects of tungsten carbide powder contents on the physical properties and pore structures 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.Secondly, the preparation of the macroporous composite matrix using culinary starch solution was studied. The effects of culinary starch solution contents on the physical properties and pore structures of matrices were studied. The results showed that macroporous are made in the composite matrix; sphericity and size distribution change little.Thirdly the article 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 residence 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. In addition, the influence in serial of mobile phases was estimated.