Design And Application Of Chitosan/Cellulose Composite Microspheres

With the development of society and the times,the energy crisis and environmental protection pressure have become the two major constraints of current social development.The dual threats of the depletion of non-renewable energy and environmental pollution caused by petroleum-based polymers has prompted people to choose to use natural renewable resources to produce new materials.Cellulose and chitosan,two of the most abundant natural polymers in nature,have attracted widespread attention due to their reproducibility,wide availability,low cost,biocompatibility and biodegradability.In this paper,cellulose and chitosan were used as matrixes to prepare functionalized composite microsphere materials by embedding functional fillers in chitosan/cellulose composite microspheres and introducing specific functional groups on the surface of composite microspheres,which were applied to the removal of tylosin and sulfamethoxazole in the aqueous phase.The main contents are as follows:?1?Used cellulose and chitosan,which are the most abundant in nature,as the matrix,activated carbon is a functional filler.The cellulose and chitosan are dissolved in Na OH/urea aqueous solution at low temperature to obtain transparent cellulose and chitosan solution.Chitosan/cellulose composite microspheres embedded with activated carbon were prepared by sol-gel method.The adsorbents had high adsorption efficiency for low concentration tylosin.SEM,BET and porosity analysis indicated that the microspheres had a multi-layered pore structure.Analysis of FTIR,XPS,Zeta potential and the effect of p H on adsorption showed that H-bond interaction,electrostatic interaction and?-?EDA interaction played the important role in adsorption process.In the batch adsorption experiment,the q_e,max of CCM-AC was 59.26 mg g^-1,the size-exclusion effect affects the rate of adsorption.The nonlinearity of the adsorption curve was significant and was consistent with the internal diffusion characteristics.Column adsorption experiments have shown that the breakthrough data fitted better with the Dose Response model.The fixed-bed column adsorption system showed a good ability to continuously treat water.Regeneration experiment shown the design adsorbents had good usability.Based on the comprehensive understanding of the adsorption mechanism,chitosan and cellulose,and AC are very suitable for using as biological affinity carrier and functional filler to design adsorbents to control antibiotic pollution.?2?An aminated chitosan/cellulose composite adsorbent was prepared by grafting a long-chain amine group onto the surface of chitosan/cellulose nanocomposite microspheres prepared by sol-gel phase inversion method by solid phase grafting.The adsorbent has high adsorption efficiency for low concentration sulfamethoxazole solution.SEM,BET and porosity analysis showed that the sample after the aminated grafting was still a microsphere with a porous structure.Analysis of FTIR,XPS,Zeta potential and the effect of p H on adsorption showed that H-bond interaction and electrostatic interaction played the important role in adsorption process.In the static adsorption experiment,the q_e,max of ACNM is 13.59 mg g^-1,which is the chemical adsorption of monolayer.The q_e increases with the increase of temperature,and the adsorption can reach an approximate equilibrium in the first 30 minutes.Dynamic adsorption experiments showed that the breakthrough data were in good agreement with Adams-Bohart,Thomas,Yoon-Nelson,BDST and dose-response models.Surface diffusion was the rate-limiting step in the adsorption process.Regeneration experiments show that the modified adsorbent has better recycling ability.The fixed bed column adsorption system showed good ability to continuously treat water,and the dynamic adsorption effect was significantly better than static adsorption,indicating that the aminated chitosan/cellulose nanocomposite microspheres have good industrial application prospects.In summary,the chitosan/cellulose-based composite microspheres designed in this paper have good stability,easy handling and recyclability.The adsorbent has high-efficiency removal ability of tylosin and sulfamethoxazole in water environment,and has broad application prospects in the field of safe water purification.