Research On Hydrophilic Modified Separating Membranes Based On Oilfield Water Treatment And Their Properties

The treatment and recovery of the large amount of oilfield wastewater had become an urgent problem in the oil well production process.Separating and purifying oilfield wastewater is an efficient way to recover resources and curb environmental pollution.Membrane separation technology is a highly efficient way to separate and purify oilfield water.In this paper,aiming at the complex oilfield wastewater is easy to contaminate membranes and the problem reduce membrane separation performance,we propose a grading method to treat the oilfield wastewater through fabricating relevant hydrophilic hybrid membrane used for treating different stage of water and constructing low-cost and high-efficient membrane integrated process technology.The results guide the improved treatment of oilfield wastewater by using membrane separating method.In view of the high concentration of oil in the initial stage of oilfield wastewater,super-hydrophilicity and underwater super-hydrophobicity polyester/ Zn O/PEI separating membrane with the micro-nano structure was fabricated.This modified membrane could remove the large oil droplets and suspended soli ds under the gravity so that the subsequent membrane fouling was decreased and energy consumption was reduced.The fabricated polyester/Zn O/PEI membrane shows t easy to be cleaned,cyclic stability,environmental stability and good antibacterial performance.The separation efficiency achieved was 99.9% after 10 separation cycles and the oil content in filtered solution is below 15 ppm.All these contribute to the separation of the complex oilfield wastewater by polyester/Zn O/PEI membrane,which significantly broad the application area of membrane.In addition,we also discussed the separation mechanism of different membranes in the oil-water separation process.The multi-scale micro-nano structure,superhydrophilicity and underwater super-hydrophobicity are the key roles that help polyester/Zn O/PEI membrane separating the oil-water mixture effectively without being contaminated by oil droplets.For the concentrated oil-water emulsion in the oilfield wastewater,the hydrophilic PES membrane modified by HPAN/Si O2 nanocomposites is designed and fabricated.The hydrophilic micro-nano structure is desired on the PES membrane to improve the hydrophilicity.The water contact angle of modified PES membrane decreased from 61° to 42° and water flux is improved to 354L/m~2?h-326% increase compared with untreated membrane.The modified PES membrane has good separation efficiency for BSA solution and different kinds of oil-water emulsions at different temperatures.Especially,the modified PES membrane still shows the excellent anti-fouling property of oil droplets even at 80 °C.Exploration of the infiltration interaction between oil emulsion and different PES membranes under different temperatures revealed the separation mechanism of different membranes at different temperatures.Because a high concentration of salt ions still existed in the later stages of oilfield wastewater,hydrophilic PA/POSS reverse osmosis membrane is fabricated for desalination.The reverse osmosis membrane is easily contaminated by bacteria during the separating process and corroded by reactive chlorine during the cleaning process,POSS modified PA reverse osmosis membrane is thus designed and synthesized by a two-step interfacial polymerization method.Taking advantage of the unique cage structure of POSS,the continuously physical barriers are built on the PA membrane surface to improve the anti-chlorine property.Moreover,the enhanced antibacterial property of the modified POSS/PA reverse osmosis membrane is enhanced owing to the remained multi-amine structures.For the PA/POSS RO membrane,the hydrophilicity is enhanced,water flux is improved,the anti-chlorine and anti-bacterial performance are enhanced.Finally,the above membranes are combined together and used to treat the oilfield wastewater produced in Daqing oilfield.After treatment,oil and salt ions in the oilfield wastewater are removed effectively,showing good separation performance.These achieved membranes could separate and purify the oilfield water effectively,provide a new research direction for oilfield wastewater separation process.