Study On Preparation And Properties Of Paper Pulp Aerogel

With the development of modern cities,more and more waste paper is produced.Therefore,it is of great significance to carry out the resource utilization of waste pulp and study the material utilization of waste pulp in the field of non-paper making.In recent years,researchers have developed several solvent systems with full components of lignocellulosic biomass,including lithium chloride/dimethyl sulfoxide,ionic liquids,etc.However,there has been no report on the use of lithium bromide solution as the solution system to prepare full components of aerogel materials.At present,there are few studies on lithium bromide solution as a solution system at home and abroad,and there is no literature report on the use of waste corrugated pulp without any pretreatment to prepare all-component aerogel materials.In this study,full component aerogel materials were prepared from discarded corrugated pulp without any pretreatment and lithium bromide solution with good solubility,no pollution and easy recovery.The research contents and results are as follows:?1?The effects of the mass fraction of waste pulp,the concentration of lithium bromide solution and the dissolution temperature on the dissolution and gel behavior of waste pulp were studied.At the same time,the structure characterization and performance test were carried out before and after the dissolution and regeneration of waste pulp.The results showed that the higher the mass fraction,the shorter the dissolution time and the shorter the gel time.The higher the concentration of lithium bromide solution,the shorter the dissolution time and the shorter the gel time.The higher the dissolution temperature,the shorter the dissolution time and the shorter the gel time.FT-IR results show that the waste pulp does not produce new functional groups in the process of regeneration and lithium bromide solution is a non-derivative solvent.XRD results show that the regenerated waste pulp dissolved hydrogen bonds between the molecules and intramolecular hydrogen bond is destroyed,crystallinity from 63.47%to 46.08%,waste paper pulp in the lithium bromide solution of regeneration after the crystal type of cellulose?type into cellulose?type.The waste pulp contains kaolinite?Al₂Si₂O₅?OH?₄?and calcite?calcium carbonate?.EDS analysis results showed that there were C,O,Al,Si and Ca elements in waste pulp,which proved the existence of kaolinite?Al₂Si₂O₅?OH?₄?and calcite?calcium carbonate?in waste pulp.The results of thermogravimetric analysis showed that the thermal decomposition temperature and thermal stability of recycled pulp decreased.?2?The optimal process conditions for the preparation of full-component aerogel after dissolving and gelating of waste pulp were studied,and the effects of waste pulp mass fractions on the morphological structure and physicochemical properties of aerogel were investigated.According to the orthogonal experiment,the order of each factor from main to second is:waste pulp mass fraction,lithium bromide solution concentration,dissolution temperature.Optimum technological conditions for waste pulp mass fraction is 1%,the lithium bromide solution concentration is 50%,the melting temperature is 140?when the preparation of aerogel maximum adsorption rate of soybean oil and diesel,respectively is19.44 g/g and 18.71 g/g.The results of nitrogen adsorption-desorption and SEM show that the aerogel materials with different waste pulp mass fraction have graded porous structure,which is conducive to adsorption of adsorbents with different sizes.The specific surface area and pore volume of aerogels were negatively correlated with the mass fraction of the waste pulp,the mass fraction of the waste pulp had little effect on the pore size of the aerogels,and the density of aerogels was positively correlated with the mass fraction of the waste pulp.FT-IR results showed that no new functional groups were produced in the process of pulp regeneration,and the mass fraction of pulp had no effect on the chemical structure of aerogel.The aerogel contains cellulose and hemicellulose,and lignin has been successfully fixed in the waste pulp aerogel network.XRD results show that the mass fraction of aerogel paper pulp chemical structure type and structure without the influence,waste paper pulp in the lithium bromide solution of regeneration after the crystal type of cellulose?type into cellulose?type.The results of thermogravimetric analysis showed that the mass fraction of waste pulp had no effect on the thermal stability of the aerogel,and the decrease of the crystallinity of the regenerated aerogel resulted in the decrease of the thermal stability of the aerogel.The results show that with the increase of density,thermal conductivity increases and thermal insulation becomes worse.The thermal conductivity of aerogel with different waste pulp mass fraction increases with the increase of humidity.?3?Hydrophobic modification of waste paper pulp aerogel by chemical vapor deposition?CVD?with methyl trichlorosilane?MTS?was carried out to prepare aerogel with hydrophobic and oil-wet properties.The structure of aerogel before and after modification was characterized and its hydrophobic,oil-water separation,adsorption and heat insulation properties were tested.The results of FT-IR,XPS and XRD indicated that the hydroxyl groups of MTS and aerogel were silanized.The results of EDS and contact Angle show that the surface and interior of aerogel are silanized.Hydrophobic surface of the aerogel and paper pulp inside the water contact Angle within 10 min did not change,the surface contact Angle is 143°,the internal contact Angle is 124°,shows that hydrophobic water gel has good hydrophobic hydrophobic performance and durable.The modified aerogel was used to separate oil and water mixture.The adsorption rate of modified aerogel on oil and organic reagents was 2-5 times higher than that before modification,and the hydrophobic waste paper pulp aerogel had higher adsorption capacity.The analysis results of thermal insulation performance showed that the thermal conductivity of aerogels before and after modification and modified aerogels 24 hours after placed at 30%-80%humidity did not change much,methyl trichlorosilane had little effect on the thermal insulation performance of aerogel,hydrophobic modification could make aerogel materials have stable thermal insulation performance.