Preparation Of Polybenzimidazole Hydrophobic Microporous Membranes And Study Of Membrane Distillation Properties

With the rapid development of my country’s industrialization,a large number of high-salt acid-containing wastewater,heavy metal wastewater and a series of toxic and harmful high-concentration wastewater are produced in the process of specific industrial production.The composition of such wastewater is complex,the water quality is different,and the treatment is difficult,and it is difficult to achieve a universal method for treatment.As an emerging technology,membrane distillation has good adaptability to the treatment of high-salt acid-containing wastewater,but the difficulty lies in the development of suitable membrane materials.For wastewater with different water quality requirements,the separation membrane material of membrane distillation needs to have excellent acid and alkali resistance,oxidation resistance and high hydrophobicity at high temperature in order to better meet the requirements of wastewater treatment.Polybenzimidazole(OPBI)has strong acid resistance and oxidation resistance,and has good structural stability in the environment of high temperature,high acid and high salt.Since the intrinsic contact angle of polybenzimidazole material is about 90°,in order to improve its hydrophobic performance,this project prepared a high-strength microporous OPBI film with a sponge pore structure.The micro-nano structure on the surface of the OPBI film is constructed by combining the spraying of high-grade Si O2 hydrophobic particles and carbon nanotubes,and the contact angle of the obtained polybenzimidazole hydrophobic microporous film exceeds 150°.After being soaked in 1 M nitric acid solution at 80 °C for 1200 hours,the contact angle decreased by less than 3% and still maintained a high hydrophobicity.The polybenzimidazole hydrophobic microporous membrane was applied to the treatment of 0.1 M nitric acid and 60 g/L aluminum nitrate solution,the flux of the Si O2 modified membrane reached 20 kg/(㎡·h)and 5kg/(m2·h),and the rejection rate Within 3h,the flux was kept above 99%,the flux of the carbon nanotube modified membrane reached 5kg/(m2·h),and the retention rate was kept above 90%.And the recovery of the polybenzimidazole hydrophobic microporous membrane is good,and it can still maintain a stable retention rate and flux after three cycles.