Preparation and characterization of macroporous cellulose–tungsten carbide composite beads for expanded bed applications

The specially designed adsorbent is one of the most important bases to achieve the expanded bed adsorption (EBA) process. The prefect adsorbents tend to be of small size, large pore and high density. In the present work a new kind of macroporous cellulose beads densified by high-density tungsten carbide were prepared through the method of water-in-oil suspension thermal regeneration. The cassava starch was used as porogenic agent during the preparation. Firstly the gelatinized starch solution was added into the cellulose viscose. After the formation of cellulose beads, the composite starch could be eliminated with boiling water wash and enzymatic hydrolyzation. The sphericity of cellulose beads was not influenced by starch addition and some amount of large pores with the diameter of about 1–3 μm could be formed in the beads. Varieties of physical properties, such as wet density, water content, porosity, specific surface area and mean pore diameter of the composite beads, as the function of starch addition were investigated. The analysis of elution peaks with model proteins (packed bed mode) indicated that the mass transfer kinetic inside the macroporous beads prepared was enhanced, which might certainly benefit the chromatographic operation under high flow rate. In addition, the prepared beads showed good expansion and stability in expanded bed, and are thus suitable for expanded bed applications.