Study On Preparation And Properties Of Modified Cellulose Gel With Selective Oxidation

Microcrystalline cellulose spherical hydrogel/aerogel is obtained by NaOH/urea/water mixed system using rich storage capacity of microcrystalline cellulose in nature as raw materials,then through the titration-suspension gelation process to obtain the new materials with three network structure which has great development and potential in the field of biomedicine,environment and building.Therefore,the preparation and application research of cellulose spherical hydrogel/aerogel has great significance.Considering the chloroform/ethyl acetate/ice acetic acid coagulation bath’s shortcoming of toxic and volatilization,a new kind of green and non-toxic carbon tetrachloride/olive oil/ice acetic acid coagulation bath was put forward in this article.Microcrystalline cellulose spherical hydrogel is successfully prepared through the improvement and optimization for the drop spherical device with the uniform shape and size,.And then through the carboxyl modification and in-situ growth successfully prepared the functional cellulose materials which has excellent characteristics and effective adsorption property.（1）Regenerated cellulose solution was obtained by NaOH/urea/water mixed system.Take carbon tetrachloride/olive oil/ice acetic acid and chloroform/ethyl acetate/ice acetic acid as coagulation bath respectively,Microcrystalline cellulose spherical hydrogel is prepared by titration suspension method successfully with the shape of uniformly.The device of drop spherical was optimized basing on the macro morphology and the requirements and control on preparation of microcrystalline cellulose spherical hydrogel.The glue head airbag to largely improved the stack,irregular shape and other problems of hydrogels after improvement.For curing part,the optimization mainly improved in seal,curing quality and time.Both the carbon tetrachloride/olive oil/ice acetic acid and chloroform/ethyl acetate/ice acetic acid had good coagulation effect,the latter has small excitant odour and nonpoisonous.For microcrystalline cellulose spherical aerogel,the interior still presented network structure and a type of cellulose II,and also it had the larger specific and the smaller diameter.The density of aerogels is small,range for 0.0312⁰.0412 g/cm3.（2）Take cellulose spherical hydrogel as matrix,TEMPO/NaClO/NaBr and TEMPO/NaClO₂/NaClO as selective oxidation system,selective oxidation（carboxylation）modified spherical hydrogel was successfully prepared by carboxyl modification.The research show that With the increation of oxidation time,the carboxyl content increases gradually,the carboxyl content can reach 1.91mmol/g When the TEMPO/NaClO₂/NaClO oxidative system dealing with 40 h,TEMPO/NaClO₂/NaClO oxidation system has a good effect of oxidation.The surface dense shell of carboxylation modified spherical aerogel dissolved gradually and the network structure of alternating with each other presented remainly after carboxyl modification.the specific surface area and pore volume have improved obviously at the same time.（3）Systematically studied the adsorption time and the solution of initial concentration for the effect that carboxyl modified spherical hydrogel absorb the methylene blue and heavy metal ions of Pb²⁺.The studies have shown that the spherical hydrogel has adsorption property which was oxidized by TEMPO/Na ClO₂/NaClO system.The adsorption of methylene blue and heavy metal ions Pb²⁺can quickly reach the adsorption equilibrium when processed 4h and 8h respectively,and the maximum adsorption capacity of BC-20 can reach 6.9632 mg/g and 5.212mg/g.（4）The magnetic carboxyl modified cellulose spherical hydrogel was prepared by the in situ synthesis method and successfully introduced the Fe₃O₄ particles into the structure of carboxyl modified cellulose hydrogel and obtained magnetic carboxyl modified cellulose spherical aerogel.The research results show that the iron element is in composite aerogel with network structure,and Fe₃O₄ particles distributed on the skeleton of cellulose uniformly.For the magnetic carboxyl modified cellulose spherical hydrogel adsorption experiments of heavy metal ions show that the magnetic carboxyl modified cellulose spherical aerogel has good adsorption on heavy metal ion Pb²⁺,and with the increation of initial concentration of Pb²⁺,the adsorption quantity increases gradually.The magnetic carboxyl modified cellulose spherical aerogel has carboxyl and magnetic double adsorption characteristics compared with cellulose aerogel.