Preparation Of Magnetic Regenerated Cellulose Microspheres Adsorbent And Their Structure Properties

The natural cellulose now has become one of the research hotspots in the water treatmentresearch field for its excellent performance. The cellulose solutions were prepared inenvironmental-friendly NaOH/Urea/H2O and NaOH/Urea/Thiourea/H2O solvent system. Naturecellulose materials were treated by ultrasonic in different dissolving stage. When the cellulosematerial was treated by ultrasonic before dissolving, the solubility of cellulose was increasedslightly while the structure and morphology of cellulose fiber was changed a lot. However, thesolubility of cellulose was increased significantly when the ultrasonic treatment was conductedduring the dissolving process. The reason may be that ultrasonic has synergistic promoting effecton dissolving process. The improvement of cellulose solubility in NaOH/Urea/H2O is greaterthan that in NaOH/Urea/Thiourea/H2O with the same ultrasonic treatment.Micron-nano regenerated cellulose microspheres were prepared by means of electrosprayingtechnology from NaOH/Urea aqueous system. The effects of processing parameters includingsurface tension, electrostatic force, solution viscosity, flow rate and electric field distribution onthe morphology and size of cellulose microspheres were investigated. The properties ofmicrospheres were characterized by SEM, FTIR and XRD. The results indicate that microsphereswith small particle size were prepared from cellulose solutions with low value of surface tension.The particle size is related to the homogeneity of solution and the volatility of solvent system.There is an obvious decrease in the particle size with an increase in the electrostatic force, whilethe particle size increases with increasing flow rate. The shape of microspheres depends onsolution viscosity significantly. With decreasing solution viscosity, the shape of particles haschanged from sphere to wedge and even strip. Meanwhile, the particle size decreases and sizedistribution increases. In addition to get the micron microspheres, we can nano particles outsidethe main product by the influence of the electric field. The regenerated cellulose microsphereshave good porosity. The molecular structure of cellulose remains but the crystal structure haschanged from cellulose I into cellulose II in the process of dissolving and regenerating. Themagnetic regenerated cellulose microspheres preserved good orbicular shape, porosity, thermalstability and superparamagnetism.According to the design of the chemical structure, regenerated microspheres prepared by thesolution blending polyethyleneimine (PEI) and cellulose, then crosslinked with glutaraldehyde.The chelate adsorption material has strong chelating characteristics of metal ions and highspecific surface area. The modified cellulose microspheres were used as adsorbent to study Pb2+removal efficiency from aqueous solution on the basis of adsorption kinetics and isothermequations. The adsorption process fit pseudo second order kinetics equation and Freundlichisotherm equation with adsorption capacity on Pb2+9.46mg·g-1. Compared with cellulose microspheres, the adsorption capacity of modified cellulose microspheres increased more than50%. This type of modified magnetic cellulose microspheres material possessed potentialapplication in the water treatment field.