Preparation Of Spherical Cellulose Beads By NMMO Process

Natural cellulose and N-methylmorpholine-N-Oxide (NMMO) were adopted to prepare the spherical cellulose beads by sequential cooling reversed-phase suspension technique. The preparation procedures were optimized. And, the physicochemical properties of the spherical cellulose beads were studied. First, the studies on the optimum preparation procedures were conducted regarding the solution of NMMO/cellulose/H₂O. The results indicated the ideal NMMO/cellulose/H₂O solution applicable to preparing the spherical cellulose beads could be obtained by adopting the raw material with mass percent of 60% under such conditions as 90¹20 ℃of the constant temperature, 250r·min^-1 of the agitation speed and over 0.095 Mpa of the vacuity. Second, the physicochemical propertoes of the NMMO/cellulose/H2O solution were studied. It was indicated the melting point of NMMO/cellulose/H₂O solution would increase with an increase of mass percent of the cellulose and a decrease of the water content. The NMMO/cellulose/H₂O solution have not apparent freezing point. And, the viscosity of NMMO/cellulose/H₂O solution also increased with the increase of the mass percent of cellulose and the cellulosic molecular weight as well as the decrease of the water content. Besides, the preparing conditions of the spherical cellulose beads by the sequential cooling reversed-phase suspension technique were optimized by the orthogonal and signal-factor experiments. The optimum operating conditions included 8.0% of the mass content of the cellulose, transformer oil as disperse phase, 4:1 of volume ratio of oil and water, Span 80 as disperse agent, 15% of the disperse agent dosage and 300 r·min-1 of the agitation speed etc. 70.0% of the mass percent of the spherical cellulose beads with particle size ranging from 0.45mm to 0.20 mm could be obtained under the above optimum conditions. In order to reduce the preparation cost and in accordace to the clean production, the waste oil was recycled. Moreover, the experiments regarding the mixing waste oil with new oil were also carried out. The results indicated the oil could be continuously reused by 2:1 of the volume ration of the waste oil and new oil. In the end, the physico-chemical properties of the prepared spherical cellulose beads were studied. The regenerated cellulosic crystalline belonged to cellulose â…¡and the crystallinity could be controlled by adjusting the preparation process. The prepared spherical cellulose with 74.0% of the moisture content had satisfactory mechanical robustness and resistant ability to acid and alkali. Consequently, the prepared spherical cellulose beads could be used to prepare the various adsorbents with different functions.