Preparation Of PES/TiO₂ Hybrid Ultrafiltration Membrane And Its Application In Treatment Of Cutting Wastewater

With the rapid development of manufacturing industry in our country,the use of cutting fluid has been greatly increased and producing large amounts of cutting waste water.If the cutting waste water is discharged into the environment without any effective treatment,it may bring great harm to the natural environment.Membrane separation technology is used for the treatment of cutting wastewater,and the recycling of the cutting wastewater can reduce pollution to the environment and save the water resource.However,in practical production,due to problems such as low permeate flux,serious membrane fouling and complicated membrane cleaning,membrane separation technology still hasn't been applied in large-scale industrialization.In this paper,TiO₂ gel was prepared by sol-gel method,and then PES/TiO₂ hybrid ultrafiltration membrane was prepared by immersion gel method,in order to be applied to the treatment of cutting wastewater.First of all,membrane structure,water contact angle,pure water flux,retention rate and other observation methods were used to find out the effects of gel bath temperature,solid content,the type of polymer additives,the content of polymer additives and the content of TiO₂ gel on the PES/TiO₂ hybrid ultrafiltration membrane.The optimum conditions of ultrafiltration membrane preparation are shown as follows:gel bath temperature is 25?,solid content is 20wt%,polymer additive is PVP,PVP content is8wt%,TiO₂ gel content is 5wt%.Under these conditions,the static water contact angle of the ultrafiltration membrane was 60.8°,the pure water flux was 226.9L/?m²·h?,and the rejection rate of bovine serum albumin was about 99.5%.Secondly,wastewater was treated by the combination of microfiltration and ultrafiltration with ultrafiltration membrane prepared by the optimized experiment,it was found that under the operating pressure 0.4MPa,feed flow rate 1.0m/s operating conditions,ultrafiltration permeate flux is 68.8L/?m²·h?.Compared with the microfiltration permeate fluid and the cutting wastewater,the pH value and defoaming properties of the ultrafiltration permeate fluid were both increased,but the conductivity,COD value,density and the average particle size of the oil droplets decreased.Under certain operating conditions above.After four hours of continuous operation,the permeate flux decreased to1/2 of the initial permeate flux.Four kinds of cleaning agents with good cleaning effect wereselected:sodiumhydroxide,hydrochloricacid,twelvesodiumalkyl sulfonate+isoamyl alcohol,citric acid.The selected cleaning agent is combined for multi-step cleaning,it is found that one-step cleaning recovery rate up to 88.7%,two-step cleaning recovery rate up to 94.5%,three-step cleaning recovery rate up to 95.4%and four-step cleaning recovery rate up to 96.9%.Finally,the ultrafiltration permeate fluid,water and cutting fluid concentrate are mixed into the cutting fluid,and then observe the performance,it was found that when the volume of ultrafiltration fluid in the cutting fluid accounted a range 0⁹0%for it's total volume,the technical requirements of cutting fluid are all up to it's standard.The 1000ml cutting wastewater was recovered and the recovery rate was 87.5%.