Preparation Of Polyamide 66 Microfiltration Membrane Modified By Nano-SiO₂/TiO₂ And Its Treatment Effect Of Oily Wastewater

With the continuous development of industry,more and more oil containing wastewater has been discharged into the water body,resulting in a lot of waste of freshwater resources,and has brought great harm to our ecological environment and human health.Membrane separation technology,as one of the most promising high-tech technologies from the end of twentieth Century to the middle of twenty-first Century,has the advantages of small footprint,simple technology and good treatment effect.It has become a promising technology for oily wastewater treatment.Polyamide 66?PA66?has advantages of excellent mechanical properties,high hydrophilicity,abrasion resistance,and corrosion resistance.In this study,nano-SiO₂ and nano-TiO₂ modified PA66 microfiltration membranes were used to treat oily wastewater and provide technical reference for the practical application of oily wastewater.This test used formic acid?FA?,formic acid and dichloromethane mixed solution of 1:1?FA/DCM?,10%methanol solution of calcium chloride?10%CaCl₂CMT?as solvent,made PA66microfiltration membrane by evaporation method,and studied the influence of the mass fraction of PA66 on membrane water flux and tensile strength properties.At the same time,this test discussed the influence of different porogen?polyethylene glycol and polyvinyl pyrrolidone?on the performance of micro filtration membrane.In addition,this text used different nanomaterials?nano-SiO₂ and nano-TiO₂?modify PA66 to determine formula and analyzed the mechanical properties,surface morphology,thermal properties and characterization of microfiltration membrane modified and unmodified,and analyzed treatment effects of modified and unmodified microfiltration membranes on the total suspended matter,COD and oil concentration in oily wastewater under different nanomaterials.Finally,this test analyzed the effect of membrane cleaning and treatment of oily wastewater.The results showed that:With the increase of mass fraction of nano materials,pure water flux and mechanical strength showed first increased and then decreased,and the contact angle showed the opposite trend.And nano-SiO₂ on membrane modification effect than nano-TiO₂ modification effect of microfiltration membrane is good.Compared with the unmodified microfiltration membrane for oily wastewater treatment,modified microfiltration membrane has good treatment effect and stable water quality and SiO₂ modified microfiltration membrane sewage treatment effect is the best.The removal rate of suspended solids,chemical oxygen demand,and oils from unmodified microfiltration membranes was 50%⁹5%,50%⁸0%,and 60%⁹2%;The removal rate of suspended solids,COD and oil from SiO₂ modified microfiltration membrane were 98%,90%and 95%,respectively;The removal rate of suspended solids,COD and oil from TiO₂ modified microfiltration membrane were 95%,85%and 88%,respectively.The use of nano-SiO₂ and nano-TiO₂ modified micro-filtration membrane significantly reduces the water flux and the removal of pollutants from the micro-filtration membrane.After washing,the water flux of the unmodified microfiltration membrane decreased,and the recovery rate of water flux was 77%.The water flux recovery rate of the nano-modified microfiltration membrane PA66-SiO₂ and PA66-TiO₂ was 92%and 96%,respectively.