Improving Pore Structure And Performance Of Thermally Cross-linked Polyacrylonitrile Membrane Via Silica Aerogel

In this article,silica aerogels were prepared by sol-gel method using methyltrimethoxysi-llane as precursor.The effects of precursor concentration,additive content and the amount of catalyst on the apparent density and porosity of the prepared aerogel were investigated.Silica sol was prepared by sol-gel method and introduced into the pores of polyacrylonitrile ultrafiltration membranes.Then,the TPAN/SiO₂ hybrid membrane was prepared through thermally cross-linking reaction.The effects of methyltrimethoxysillane concentration and precursor type on the pore structure and performance of the TPAN/SiO₂ hybrid membrane were investigated.The pore structure and performance of the TPAN/SiO₂ hybrid membranes were characterized by means of SEM,FTIR,XPS,TGA and permeability.The results were obtained as follows:?1?Silica aerogels were prepared by sol-gel method using methyltrimethoxysillane as precursor.The effects of precursor concentration,additive content and the amount of catalyst on the apparent density and porosity of the prepared aerogel were investigated.When MTMS:H₂O:CTAB:HCl=1:51:1.56×10^-3:1.42×10^-3,the prepared silica aerogel had an apparent density of 0.076 g/cm³ and a porosity of 96.5%.?2?Silica sol was prepared by sol-gel method using methyltrimethoxysillane as the precursor and introduced into the pores of polyacrylonitrile ultrafiltration membranes.Then,the TPAN/SiO2 hybrid membrane was prepared through thermally cross-linking reaction.With the increase of methyltrimethoxysillane concentration,the average effective pore size and water flux of the TPAN/SiO2 hybrid membrane both increase and the TPAN/SiO2 hybrid membranes have the higher rejection rate for BSA above 98%;when the mass concentration of methyltrimethoxysillane is 14%,the average effective pore size of the hybrid membrane is2.88 nm and the pure water flux can reach 4.42 L/?m²·h·bar?.?3?The rejection effect of the TPAN/SiO₂ hybrid membranes for different inorganic salts as follow:Na₂SO₄>MgSO₄>MgCl₂>NaCl,and the TPAN/SiO₂ hybrid membranes was negatively charged.?4?The TPAN/SiO₂ hybrid membrane shows excellent thermal stability which can persist up to 280 ^oC without any large mass and has good solvent resistance that there was not changed significantly on the membrane surface and cross-section after the hybrid membranes being soaked in DMAc for ten days.?5?The three types of TPAN/SiO₂ hybrid membrane were prepared by sol-gel method using methyltrimethoxysillane,mixed precursor and tetraethyl orthosilicate as precursors.Silica sol was prepared by sol-gel method using tetraethyl orthosilicate as the precursor and introduced into the pores of polyacrylonitrile ultrafiltration membranes.Then,the TPAN/SiO₂hybrid membrane was prepared through thermally cross-linking reaction,which was the best to restrict the collapse of pore structure during the thermal crosslinking process.