Study On The Controllable Preparetion And Adsorption Performance Of Cellulose-based Microspheres

With the social economic continuous development,a large amount of wastewater containing organic pollutants and heavy metal ions was directly discharged into ecosystem,seriously harming human health and biological safety.Among various water treatment technologies,adsorption method was considered as a cost-effective method.It has important practical significance to find an adsorbent with excellent performance.However,there are still many problems to be solved in the preparation of porous cellulose microspheres,such as the difficulty of controlling the preparation process,the complexity of the process,and the need to add porogens.In order to solve these problems,in this study,cellulose was selected as the raw material,and a variety of cellulose-based microspheres were prepared by microfluidic and flash freezing method.The influence of preparation conditions on the composition and microstructure of the microspheres was investigated systematically.On this premise,the adsorption properties of the microspheres were compared and analyzed.The specific research contents are as follows:(1)Using cellulose as a precursor,Pourous cellulose acetate microspheres(PCMs)were prepared by microfluidic droplet preparation technology and rapid freezing pore-forming technology.The effects of microfluidic parameters,the types of solvents and the concentration of solutes on the microstructure and morphology of the porous cellulose microspheres were systematiclly investigated.In addition,the adsorption properties of the porous cellulose microspheres were studied.The characterization was measured by scanning electron microscopy(SEM),Fourier transform infrared spectroscopy(FTIR),and specific surface area measurement(BET).The prepared porous cellulose microspheres were highly specific surface area,uniform paticle sizes,and precise control of microsphere structure and morphology.Moreover,the adsorbents showed good adsorption capacityfor target pollutants(qe=23.90mg/g).(2)Firstly,Nano-hydroxyapatite particles was generated by chemical precipitation method.Then they thoroughly mixed with cellulose solvent to form precursor solution.Nano-hydroxyapatite/cellulose composite microspheres(nHCMs)with uniform particle size were prepared using microfluidic technology.Moreover,the chemical structure and micro-morphology of the composite microspheres were analyzed by using X-ray powder diffraction(XRD),FTIR and SEM.On this basis,nano-hydroxyapatite addition amount,adsorption time,initial pH value and initial concentration of Congo red on the adsorption performance of composite microspheres were investigated.The results showed that nano-hydroxyapatite was successfully prepared and distributed evenly on the porous cellulose microspheres.The composite microspheres showed great adsorption properties for Congo red dyes(q_e=97.82 mg/g).The adsorption kinetic was described well by the pseudo-second order kinetic model.(3)Calcium carbonate/cellulose composite microspheres were synthesized using microfluidic technology.Then,Calcium carbonate/cellulose composite microspheres were immersed in phosphate buffer solution by in-situ conversion method to form Nano-hydroxyapatite/cellulose composite microspheres(T-nHCMs).Moreover,composite microspheres were chatacted by XRD,FTIR and other instruments.By changing the amount of adsorbent,adsorption temperature,adsorption time,initial pH and initial concentration of Congo red,the effect of different conditions on the adsorption effect of composite microspheres was investigated.In addition,the adsorption mechanism was analyzed by using the adsorption kinetic theory and thermodynamics theory based on the fitting results.The results showed that the composite microspheres as adsorbents have a high efficiency of adsorbing Congo red(q_e=195.93 mg/g).And the adsorption performance of composite microspheres could be described by the Pseudo-second-order kinetics and Langmuir adsorption isotherm model.