Synthesis,Modification And Properties Of Alginate-silica Composite Aerogels

The alginate-silica composite aerogel was prepared by one-pot sol-gel method and freezing drying technology with alginate and tetraethoxysilane(TEOS)as the co-precursor.In order to improve the stability,the composite aerogels were modified by using methyltrimethoxysilane(MTOS)as hydrophobic modifier.The chemical structure,morphology,physical properties of the resulty and their potential in the oil absorption were investigated.According to Fourier Transform Infrared Spectroscopy(FTIR)and Thermo gravimetric analyse,the alginate-silica composite aerogels were successfully prepared xand modified.The interpenetrating networks composed of silica nanoparticles and nanofibres of alginate could be observed by Scanning Electron Microscope(SEM).The micro-structure of the modified aerogels was denser than that of unmodified aerogels.The mass ratio of alginate had significant effect on physical properties of composite aerogels.Aerogels with 30%(wt%)alginate showed optimal physical properties.The water contact angle tests demonstrated that the modified aerogels were hydrophobic.The maximum compressive modulus of the composite aerogels reached up to 6.125MPa when the mass ratio of alginate was 30%.The absorption capacity of the hydrophobic composite aerogels increased with increase in pore volume,and they could absorb oil or organic solvents in 10 minutes.Cycle absorption-desorption tests indicated that the composite aerogels could be used more than 10 times.In conclusion,the optimal properties were obtained when the mass ratio of alginate was 30%:the bulk density,skeleton density,porosity and pore volume were0.134 g/cm~3?1.246 g/cm~3?89.2%and 16.22cm~3/g respectively,compressive modulus was 6.125MPa,water contact angle was 120.5°,and the absorption capacity for oil or organic solvents was 9.22-18.26g/g.The excellent repeat properties and fast absorption velocity indicated promising application prospect in the oil absorption.