Preparation And Membrane Aeration Performance Of Crosslinked PDMS/PVDF Microporous Membrane

Hydrophobic microporous membrane aeration technology is a water pollution treatment technology in which oxygen passes through the hydrophobic microporous membrane to dissolve in the water,thereby increasing the dissolved oxygen content in the water to improve water quality.Hydrophobic microporous membranes can be used as carriers for microbial membranes to make membrane bioreactors(MBR).For this article,the cross-linked PDMS/PVDF hydrophobic microporous flat membrane was prepared by the non-solvent induced phase separation(NIPS).Through dry/wet spinning technology,crosslinked PDMS/PVDF hollow fiber membrane was prepared.First,the influence of the amount of porogen(Li Cl)on the structure and performance of the flat membrane was explored.The membrane was characterized by SEM,ATR-FTIR,pore size,mechanical properties and water contact angle.The results showed that the membrane had a semi-interpenetrating polymer network(semi-IPN)structure.With the increase of Li Cl,the viscosity of the casting liquid increases;the average pore size and porosity of the membrane first gradually increased and then decreased;the hydrophobicity of the membrane first increased and then decreased;the thermal stability of the membrane increased slightly;the mechanical strength first decreased and then increased.Then,the effect of the mass ratio of PDMS/PVDF on the structure and performance of the crosslinked membrane under constant viscosity conditions was studied.The membrane was characterized by SEM,ATR-FTIR,pore size,mechanical properties and water contact angle.The results showed that as the mass ratio of PDMS/PVDF increased,the finger-like pore structure of the flat membrane increased,and the sponge-like pores decreased;the hydrophobicity of the membrane gradually increased,and the thermal stability of the membrane decreased;and the elongation at break of the membrane gradually increased.The breaking strength and Young’s modulus of the hollow fiber membrane gradually decreased,and the elongation at break first increased and then decreased.Finally,the aeration performance of PDMS/PVDF microfiltration membrane was studied.The experimental results showed that the flat membrane under the conditions of aeration pressure of 5KPa and temperature of 25℃,when the addition ratio of Li Cl was1.5%,and the mass ratio of PDMS/PVDF was 5/15,the prepared cross-linked PDMS/PVDF membrane had the best membrane aeration performance.When the membrane M4-5 was aerated for 180 minutes,the dissolved oxygen content in the water reached saturation,and the DO was 8.84 mg/L.When the addition ratio of Li Cl was 1.5% and the mass ratio of PDMS/PVDF was 5/15,the hollow fiber membrane had the best membrane aeration performance.When the membrane H-5 was aerated for 360 min,the dissolved oxygen content in the water reached saturation,and the DO value was 8.84 mg/L.