Synthesis,Modification And Properties Of Gelatin-silica Composite Aerogels

In this paper,porous gelatin-silica composite aerogel was prepared by sol-gel and freeze-drying method.TEOS and gelatin were used as precursors.Then hexamethyldisilazane was used as modifier to prepare hydrophobic gelatin-silica composite aerogel through two-step method.The chemical structure,microstructure,characteristics of pores and potential applications in the field of oil absorption were systemically studied.Firstly,gelatin-silica composite aerogel was prepared by sol-gel and freezing-drying method.Fourier transform infrared spectroscopy(FTIR)and X-ray diffraction(XRD)illustrated that gelatin-silica composite aerogel was prepared successfully.Compared with nanoparticles of silica aerogel,gelatin-silica composite aerogel showed porous structure with uniform and stable beads.With the increase of gelatin content,the bulk density decreased firstly and then increased while the porosity increased firstly and then decreased.When the gelatin content was 30%,composite aerogel showed the lowest density and the maximum porosity.Then,HMDS was used as modifier and hydrophobic gelatin-silica composite aerogel was obtained.The structure,morphologies,pore volume,thermal stability,compressive property,as well as oil absorbency of hydrophobic composite aerogel were investigated.The results illustrated that the content of hydroxyl was decreased significantly and the porous structure of composite aerogel after hydrophobic modification was looser.With the increase of gelatin content,pore volume of hydrophobic composite aerogel increased firstly and then decreased.Composite aerogels with 30 wt% gelatin(30-GS)had the largest pore volume of 1.21 cm3/g.30-GS had compressive strength of 1.56×104 N/m~2,proving the improvement of mechanical property.Hydrophobic composite aerogels were thermally stable up to nearly 335-345°C.Water contact angle was more than 117°,which showed the excellent hydrophobic and lipophilic property.Finally,the oil absorption equilibrium could be achieved in 15 minutes.30-GS had relatively high oil absorbency of 27 g/g for xylene and could be reused up to 10 times.Therefore,hydrophobic gelatin-silica composite aerogel showed great development prospects in oil absorption field.