Preparation And Study Of Sodium Borosilicate Glass Hollow Fiber Membranes

Inorganic membranes show excellent performances in thermal,chemical and mechanical resistance.Among them,glass membranes are attached more and more attentions due to their flexible geometric form,tailorable pore size and narrow pore size distribution.Methods available to prepare glass hollow fiber membrane include melt-spinning,sol-gel and chemical vapor deposition,but there is no research that adopt solution-spinning method namely dry-wet spinning to prepare glass hollow fiber membrane.So dry-wet spinning connecting with phase separation-leaching mechanism is adopted to prepare sodium borosilicate glass hollow fiber membrane in this paper.The composition of glass most suitable for phase separation is firstly confirmed on the basis of phase diagram.Sodium borosilicate glass was then prepared by melting quartz sand,borax and boric acid.Research suggested that the degree of phase separation increased first and then reduced with increasing of temperature and time.The most suitable temperature and time for phase separation are concluded to be 550? and 16 h respectively.While the milling of glass powders,ceramic balls proved to be best performing compared with the other two milling balls.A well-distributed casting solution is prepared by strong stirring of glass powder,poly(vinylidene fluoride),polyethyleneglycol and dimethylacetamide.A 60 wt.%of glass powder proved to be appropriate via the viscosity test.During the dry-wet spinning process,it was found that the finger-like region and porosity of spinned precursors decreased with the increase of pulling rate.During the sintering of precursors,it was found that with the raise of temperature,the porous region decreased while the bending strength increased,and the hydrophilic performance degraded first and then improved.It was found in the leaching of hollow fibers that the average pore width,surface area and pore volume of membrane reduce with the increase of nitric acid concentration,and the narrowest pore width distribution achieved when the concentration reached 3 mol/L.The pure water flux of glass membranes leached by nitric acid with different concentration increased in different levels as test began,and then remain steady in the further test while the highest steady value is 134 L/(m2·h).The membranes' rejection rate of carbon with different nitric acid concentration were all above 99%,and the rejection rate of bovine serum albumin increased with the increase of nitric acid concentration while the maximum is 50.4%.