Study On Sulfated Y-doped Nonstoichiometric Nanosized ZrO₂/PSF Composite Membranes

A great deal of wastewater containing oil is produced from oil exploitation processes. Draining of wastewater containing oil not only pollutes the environment, but also reduces the yield of oil. Many conventional methods including gravity settling, dewatering and incineration perform can not efficiently treat emulsified and soluble oil. Membrane filtration has emerged as a useful process for concentration and clarification of wastewater containing oil. But large-scale applications of the membrane separation process for wastewater containing oil are limited because polymer membranes are easy to be contaminated by oil. Therefore, development of antifouling membranes is a most pressing task at present.In this paper, to enhance hydrophilic property of polysulfone (PSF) membranes, novel organic-inorganic composite membranes were prepared by a process of adding SOB4BP2-P/ZrOB2B-YB2BOB3 Bwith higher activity and hydrophilic property to the porous matrix of PSF. Sulfated Y-doped nonstoichiometric nanosized ZrOB2B (SOB4BP2-P/ZrOB2B-YB2BOB3B) was synthesized by doping ZrOB2B with rare element Yttrium and modifying with sulfate simultaneously. The optimal preparation conditions of composite membranes were: PSF concentration, 14 wt.%; mass ratio of PEG 400 to PSF, 10%; mass ratio of SOB4BP2-P/ZrOB2B-YB2BOB3B to PSF, 15%; evaporating time, 10s; coagulation bath temperature, 20 oC; use of ultrasounds, batch operation.Measurements of tensile strength, contact angle and resistance to compactability show that mechanical strength, hydrophilic property and resistance to compactability are improved to a large extent, respectively. ESEM micrographs indicate that the composite membrane owning the asymmetry structure has two layers of compact layer and porous layer and that SOB4BP2-P/ZrOB2B-YB2BOB3B is uniformly dispersed in PSF.An oil-in-water emulsion containing machine oil of 80 mg/L in de-ionized water (wastewater containing oil) was used to test the separation performances of membranes with different casting solutions. The results indicate that oil retention of 99.16â„… and oil concentration of 0.67 mg/L in permeate are achieved, which meet the requirement for discharge (<10 mg/L). The flux in treatment of wastewater containing oil is greatly increased, so it reveals that anti-fouling ability is significantly enhanced and treatment of wastewater containing oil using composite membranes developed is feasible and desirable. At last, hydrophilic property formative mechanism was preliminarily discussed in order to explain from the theory point why anti-fouling ability of composite membranes was enhanced.