جستجوی مقالات مرتبط با کلیدواژه « غشای الیاف توخالی » در نشریات گروه « فنی و مهندسی »

Water pollution with petroleum compounds is one of the most important environmental problems in oil-rich countries, due to its adverse effect on soil, water, and human beings. The hydrophilic hollow fiber membranes were produced by polymer blending of polyamide imide and sulfonated poly ether ether ketone. Membrane structure and function were investigated by field emission scanning electron microscopy analysis, N2 permeation, overall porosity, collapse pressure, water contact angle, pure water flux tests. A membrane bioreactor system was used for oily wastewater treatment. From FESEM, a more open structure with larger finger-like was observed by increasing the PAI / SPEEK ratio. Using the PAI / SPEEK ratio of 85/15, the water contact angle of the membrane was decreased from 74° to 58° which showed a significant hydrophilicity improvement. From compaction test, pure water flux of the membranes showed a gradual decrease during 2.5 h and then reached a steady state with minimal changes. During a period of about 5 hours of the oil separation through the MBR process, the plain PAI membrane and the blend PAI-SPEEK membrane showed water flux reduction of about 35% and 21%, respectively. Under 5 bar transmembrane pressure and the addition of 30 mg/l of oil spill eater (OSEII) enzyme, the oil concentration decreased from 36 ppm to 1.2 ppm in the wastewater, which represents the oil removal efficiency of about 97%. In this work, the optimum state for oil removal was obtained in terms of adding OSEII and aeration.

 Hydrophobic surface modifying macromolecules (SMM) have a main chain of polyurethane with two ends having a fluorine-based hydrophobic polymer. These macromolecules tend to migrate to the membrane surface during membrane fabrication process and alter the physical and chemical properties of the membrane surface by formation of a thin layer on the surface of the membrane. Therefore, they can increase the hydrophobicity of the membrane surface which is an important parameter in gas-liquid membrane contactor system.

Poly(vinylidene fluoride-co-chlorotrifluoroethlene), PVDF-CTFE, hollow fiber membranes were fabricated using surface modifying macromolecules through a dry-wet phase inversion method. Structure and characteristics of fabricated membranes were evaluated and they were used in carbon dioxide absorption and stripping processes in a gas-liquid membrane contactor system.

Water contact angle of outer surface of the fabricated membrane without SMM was measured as 90.51°. Addition of SMM into the membrane increased contact angle to 114.20°. Critical entry pressure of water of the membrane fabricated without/with SMM was measured as 7 and 10.50 bar, respectively. The CO2 absorption flux of 1.76×10-3 mol/m2.s and 9.70×10-4 mol/m2.s, at the liquid phase flow rate of 300 mL/min, was achieved for the fabricated membrane without/with SMM, respectively. The CO2 stripping flux, at the liquid flow rate of 200 mL/min, for the fabricated membrane was achieved at 1.30×10-3 mol/m2.s without SMM and 6.40×10-4 mol/m2.s with SMM. The maximum CO2 stripping efficiency, at the liquid flow rate of 200 mL/min, was achieved for the fabricated membrane at 72.10% without SMM and 42.60% with SMM.

Polymeric hollow fiber membranes with high area per unit volume are proper configurations in membrane technology. Linear low density polyethylene (LLDPE) with specific properties is a suitable polymer for fabrication of hollow fiber membrane through thermally-induced phase separation method. The aim of this study was to evaluate the effect of different extractants, take-up speed and bore fluid flow rate on the structure and performance of LLDPE hollow fiber membranes. The LLDPE and mineral oil were heated in order to obtain a homogeneous solution and fed to spinneret. The hollow fiber extruded from the spinneret entered into a coagulation bath and then extracted by different extractants. The effects of ethanol, hexane and acetone with different solubility parameters were studied on the structure of membranes. In the following, the effect of take-up speed and bore fluid flow rate was studied with respect to the structure as well as performance of membranes extracted with acetone. Membranes extracted with ethanol showed low porosity and water permeability which implied that ethanol cannot extract diluent. Due to similar solubility parameter of hexane and LLDPE, hexane swells the amorphous region of the polymer and it blocks the pores. Acetone extracted the diluent successfully and the SEM images confirmed porous structure of the membranes. The other results showed that pure water permeability, surface roughness and tensile strength of the hollow fiber membranes increased when the take-up speed was increased. In addition, raising the bore fluid flow rate improved the strength of the membrane while it reduced the water permeability. Finally, it was revealed that the rejection of membranes in the separation of collagen protein solution was increased by increasing bore fluid flow rate and also decreased slowly by increasing the take-up speed.

The objective of this study was to evaluate the feasibility of treating desalting plant produced water to meet the applicable discharge limits and injection to well standard consistently using membrane processes to either reduce the risk of clogging of the injection well. The effluent of sand filtration unit from Aghajari maroon 2 produced water treatment was used as a feed. A Pilot scale hybrid membrane unit with a spun polypropylene 0.45 µ pore size microfilter and a hollow fiber polypropylene 0.1 to 0.01 µ pore size ultrafilter membrane was used in this study. Trials on different membrane fluxes were conducted for three processes: microfiltration, ultrafiltration and hybrid micro and ultrafiltration process. Results have shown that flow rate of 32 LPM was more applicable. The optimal flux was 120 LMH. The average percentage removal of Turbidity, Oil and grease, TSS and particle size was 98.53, 98.81, 98.23 and 99.93 respectively. The results showed that the quality of the product consistently met the requirement for injection to well. It was concluded that it is feasible to treat the produced water using micro and ultra filter.