The Preparation And Structure Control Of Konjac Glucomannan-Based Aerogels

Aerogel is a kind of porous network structure with high dispersion of solid material,that has been widely used in gas adsorption filtration and catalyst carrier materials.It has great potential in cigarette filter material.In this paper,a polysaccharide aerogel,which is based on polysaccharide starch and Konjac Glucomannan(KGM)and prepared by sol-gel and frozen-dry process,is introduced.Then,the material is characterized in this study and its preparation mechanism,mechanical properties and application in the cigarette is also discussed.(1)In this study,the Konjac Glucomannan(KGM)of Polysaccharide are used as main raw materials of the polysaccharide cryogels.And they were prepared by using frozen-dry method.The influences of preparation temperature,time,stirring speed,pre-frozen time on mechanics properties of polysaccharide aerogels were analyzed,and the preparation conditions were optimized by the response surface methodology(RSM).The optimal preparation conditions determined by RSM were: preparation temperature 90 ?,stirring speed 800 RPM,preparation time 60 min and the Pre-freezing time 14 h.Under these conditions,the hardness and springiness of the aerogels were 8.38 N and 1.89 mm.(2)Higher pre-frozen temperatures would drive to form the big ice crystals and irregular aerogels pore structure formed;lower pre-frozen temperatures could drive to smaller and uniform size ice crystals and aerogels pore structure formed.Higher KGM concentration would form fine but layer distribution ice crystal and aerogels pore structure;lower KGM concentration could form multilateral structure ice crystals and irregular aerogels pore structure formed.Higher monoglyceride concentration could form big size ice crystals and radial aerogels pore structure,lower monoglyceride concentration could form messy ice crystals and irregular aerogels pore structure formed.When the pre-frozen temperature was-25°C,the KGM concentration was 0.3%,the glyceryl monostearate concentration was 0.1%,ice crystals of uniform size(14.5 um,65.1%)were formed,thus dense and uniform pore structure(71.2 um,73.6%)aerogels obtained.(3)Scanning electron microscopy(SEM)revealed that the polysaccharide cryogel is stereo three-dimensional(3-D)porous network structure with many holes inside.Measurement of specific surface area shows that samples have a high surface area,a lower density,and the specific surface area is 1.338 m2/g,the total pore volume is 8.5757 ml/g,the porosity is 96.24%,the average pore size is 25.6 um.The sample is easy to moisture absorption in the environment.The moisture absorption rate is higher with the high humidity of environment,and it had a negative correlation with its hardness but had a positive correlation with its springiness.(4)According to the result of experiment in which the samples were added to filters of cigarette,the new filter satisfy the physical indexes of cigarette,which could reduce total particle matter(reduced by 14.25%),tar(reduced by 13.07%),nicotine(reduced by 26.13%),CO(reduced by 11.92%)of cigarette smoke mainstream.The adsorption effect is more significant in flue gas,compared with commercially available filter.