scholarly journals Coalescence of Oil Droplets using Sponge-like Structure of Polyvinylidene Fluoride Membranes

2018 ◽  
Vol 23 (1) ◽  
Author(s):  
C. K. Chiam ◽  
M. Nurashiqin ◽  
K. Zykamilia ◽  
N. M. Ismail ◽  
K. Duduku ◽  
...  
Keyword(s):  
Size Distribution ◽  
Polyvinylidene Fluoride ◽  
Produced Water ◽  
Feed Solution ◽  
Transmembrane Pressure ◽  
Oil Droplets ◽  
Membrane Pore ◽  
Pore Sizes ◽  
Phase Inversion Technique ◽  
Membrane Pore Size

This work reports the effect of the membrane pore size distribution on the oil droplets size distribution in permeate using the polyvinylidene fluoride (PVDF) membranes. The sponge-like structures of the PVDF membranes were fabricated via the phase inversion technique using 30% v/v ethanol aqueous solution as coagulation medium. Water and polyethylene glycol (PEG1000) were used as the pore forming additives in the dope solutions. Microfiltration was employed to coalesce the oil droplets at the transmembrane pressure of 2.5 bar. Simulated alkaline-surfactant-polymer (ASP) produced water was tested as the feed solution. Results revealed that the PVDF membranes with sponge-like structure were formed. The additives in the dope solutions have induced the membranes to become thicker due to more porous, spongy and resilient structure. The membrane pore sizes increased with the presence of the additives in the dope solutions especially when larger molecular weight of the additive, i.e., PEG1000 was used. The mode of the oil droplets radius increased from 61.2 nm in the feed solution to 95.1, 356.2 and 1335 nm in the permeates by the corresponding membranes without additive, with water and PEG1000 as the additives. The membranes with larger pore sizes as well as more open structure were able to trap and coalesce more oil droplets which produced larger size of the oil droplets in the permeates.

Occurrence and removal of microbial indicators from municipal wastewaters by nine different MBR systems

2012 ◽  
Vol 66 (4) ◽  
pp. 865-871 ◽  
Author(s):  
Zakir M. Hirani ◽  
James F. DeCarolis ◽  
Geno Lehman ◽  
Samer S. Adham ◽  
Joseph G. Jacangelo
Keyword(s):  
Fecal Coliform ◽  
Polyvinylidene Fluoride ◽  
Coliform Bacteria ◽  
Membrane Pore ◽  
Microbial Indicators ◽  
Membrane Materials ◽  
Pore Sizes ◽  
Wide Range ◽  
Membrane Pore Size ◽  
The Impact

Nine different membrane bioreactor (MBR) systems with different process configurations (submerged and external), membrane geometries (hollow-fiber, flat-sheet, and tubular), membrane materials (polyethersulfone (PES), polyvinylidene fluoride (PVDF), and polytetrafluoroethylene (PTFE)) and membrane nominal pore sizes (0.03–0.2 μm) were evaluated to assess the impact of influent microbial concentration, membrane pore size and membrane material and geometries on removal of microbial indicators by MBR technology. The log removal values (LRVs) for microbial indicators increased as the influent concentrations increased. Among the wide range of MBR systems evaluated, the total and fecal coliform bacteria and indigenous MS-2 coliphage were detected in 32, 9 and 15% of the samples, respectively; the 50th percentile LRVs were measured at 6.6, 5.9 and 4.5 logs, respectively. The nominal pore sizes of the membranes, membrane materials and geometries did not show a strong correlation with the LRVs.

Pilot Study on Ultrafiltration of Produced Water from Polymer Flooding for Reuse

2010 ◽  
Vol 113-116 ◽  
pp. 1266-1269 ◽  
Author(s):  
Jun Xu ◽  
Wen Xin Shi ◽  
Shui Li Yu ◽  
Wen Ming Qu
Keyword(s):  
Crude Oil ◽  
Polyvinylidene Fluoride ◽  
Produced Water ◽  
Reduction Factor ◽  
Polymer Flooding ◽  
Transmembrane Pressure ◽  
Operation Conditions ◽  
Membrane Flux ◽  
Crossflow Velocity ◽  
Hydrolyzed Polyacrylamide

Produced water from polymer flooding (PWfPF) in oilfield is high contents of crude oil, total suspension substance (TSS), hydrolyzed polyacrylamide and salinity. Most existing traditional processes in China are incapable to treat PWfPF to meet the reinjection water quality for low and ultra-low permeability reservoirs. In the present paper, a hydrophilized tubular polyvinylidene fluoride (PVDF) membrane with a total active area of 110 m2 manufactured by our laboratory was used for ultrafiltration of the PWfPF. The temperature and volume reduction factor (VRF) of the PWfPF were fixed at 37 °C and 4, respectively. The influences of transmembrane pressure (TMP) and crossflow velocity on the membrane flux were investigated. The experimental results showed that a TMP of 0.20 MPa and crossflow velocity of 4.5 m/s were the optimum operation conditions. Under the above conditions, long-term filtration experiments were conducted for 12 months to evaluate the effectiveness of the membrane. The obtained results revealed that the membrane average flux could reach 75 L/(m2•h) and the flux recovery was more than 95%. In the permeate, the content of crude oil and turbidity were respectively lower than 1 mg/L and 1 NTU, while the TSS was consistently below detection limits (2.5 mg/L), all of which reached the highest reinjection criteria for oilfield in China and demonstrated that the membrane has a good anti-fouling characteristics to PWfPF.

scholarly journals An Efficient Method to Determine Membrane Molecular Weight Cut-Off Using Fluorescent Silica Nanoparticles

Membranes ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 271
Author(s):  
Mariam Fadel ◽  
Yvan Wyart ◽  
Philippe Moulin
Keyword(s):  
Molecular Weight ◽  
Silica Nanoparticles ◽  
Retention Rate ◽  
Transmembrane Pressure ◽  
Experimental Conditions ◽  
Membrane Pore ◽  
Fluorescent Silica Nanoparticles ◽  
Wide Range ◽  
Membrane Pore Size ◽  
Different Diameters

Membrane processes have revolutionized many industries because they are more energy and environmentally friendly than other separation techniques. This initial selection of the membrane for any application is based on its Molecular Weight Cut-Off (MWCO). However, there is a lack of a quantitative, liable, and rapid method to determine the MWCO of the membrane. In this study, a methodology to determine the MWCO, based on the retention of fluorescent silica nanoparticles (NPs), is presented. Optimized experimental conditions (Transmembrane pressure, filtration duration, suspension concentration, etc.) have been performed on different membranes MWCO. Filtrations with suspension of fluorescent NPs of different diameters 70, 100, 200 and 300 nm have been examined. The NPs sizes were selected to cover a wide range in order to study NPs diameters larger, close to, and smaller than the membrane pore size. A particle tracking analysis with a nanosight allows us to calculate the retention curves at all times. The retention rate curves were shifted over the filtration process at different times due to the fouling. The mechanism of fouling of the retained NPs explains the determined value of the MWCO. The reliability of this methodology, which presents a rapid quantitative way to determine the MWCO, is in good agreement with the value given by the manufacturer. In addition, this methodology gives access to the retention curve and makes it possible to determine the MWCO as a function of the desired retention rate.

Comparative study of polyvinylidene fluoride and PES flat membranes in submerged MBRs to treat domestic wastewater

2009 ◽  
Vol 59 (3) ◽  
pp. 399-405 ◽  
Author(s):  
T. Zhu ◽  
Y. H. Xie ◽  
J. Jiang ◽  
Y. T. Wang ◽  
H. J. Zhang ◽  
...  
Keyword(s):  
Polyvinylidene Fluoride ◽  
Domestic Wastewater ◽  
Membrane Bioreactors ◽  
Membrane Pore ◽  
Pvdf Membrane ◽  
Membrane Flux ◽  
Removal Efficiencies ◽  
Membrane Pore Size ◽  
Pes Membrane ◽  
Flat Membranes

Two kinds of membranes, polyvinylidene fluoride (PVDF) and polyethersulfone (PES), were used in submerged flat membrane bioreactors (MBRs) to treat domestic wastewater in this study. The MBRs ran under the same reactor structure, the same membrane pore size of 0.45 μm and the same anoxic/ oxic (A/O) process. The experimental results showed that: (1) With the influent of BOD5 200–500 mg/L and CODCr 400–1,000 mg/L, PVDF MBR achieved the removal efficiencies of BOD5 96–98% and CODCr 89–98%, and those were 97–99% and 93–97% in PES MBR. The interceptive efficiency of PES membrane to BOD5 and CODCr was superior to PVDF membrane. (2) The removal efficiencies of TN and NH3-N in two MBRs exhibited good results which were greater than 85%. The removal efficiencies of TP were greater than 80% in both MBRs. (3) MLSS concentration changed from 2,000 mg/L to 7,000 mg/L during the experiment. PES membrane was not washed and the membrane flux was steady. However, the flux of PVDF one decreased quickly and was washed for twice. It meant that PES membrane had fine capability than PVDF one.

scholarly journals Porous Gelatin Membranes Obtained from Pickering Emulsions Stabilized with h-BNNS: Application for Polyelectrolyte-Enhanced Ultrafiltration

Membranes ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 144 ◽  
Author(s):  
Molka Nafti Mateur ◽  
Danae Gonzalez Ortiz ◽  
Dorra Jellouli Ennigrou ◽  
Karima Horchani-Naifer ◽  
Mikhael Bechelany ◽  
...  
Keyword(s):  
Pore Size ◽  
Water Permeability ◽  
Hexagonal Boron Nitride ◽  
Pure Water ◽  
Transmembrane Pressure ◽  
Pickering Emulsions ◽  
Drying Time ◽  
Membrane Pore ◽  
Membrane Pore Size ◽  
Water Swelling

In recent years, numerous studies have been conducted to develop biopolymer-based membranes, highlighting the challenges to prepare porous structures with control porosity. In this paper an innovative method that relies on the generation of Pickering emulsions was developed to prepare porous membranes from gelatin for filtration purpose. Hexagonal boron nitride nanosheets (h-BNNS) were used to stabilize micro-droplets of castor oil in a continuous homogeneous gelatin solution. Two steps in the membrane preparation process strongly influenced the porous structure. Specifically, the duration of the drying time after emulsion casting and the duration of the cross-linking step affected membrane pore size, hydrophobicity, water swelling, and water permeability. By controlling these two steps, membranes could be designed with pore size between 0.39 and 1.60 μm and display pure water permeability between 150 and 506 L h−1 m−2 bar−1. These membranes have been tested for complexation–ultrafiltration experiments in which iron ions were removed from aqueous solutions with/without poly (acrylic acid) (PAA). Without PAA, the removal of free iron (II) ions was low (not more than 14%). The addition of PAA (200 ppm) allowed obtaining high removal rates (97%) at pH ≥ 5 with 3 bars of transmembrane pressure.

scholarly journals Combined Effect of Colloids and SMP on Membrane Fouling in MBRs

Membranes ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 118 ◽  
Author(s):  
Dimitra Banti ◽  
Manassis Mitrakas ◽  
Georgios Fytianos ◽  
Alexandra Tsali ◽  
Petros Samaras
Keyword(s):  
Membrane Fouling ◽  
Oxygen Demand ◽  
Membrane Bioreactors ◽  
Combined Effect ◽  
Transmembrane Pressure ◽  
Soluble Microbial Products ◽  
Treatment Efficiency ◽  
Membrane Pore ◽  
Microbial Products ◽  
Membrane Pore Size

Membrane fouling investigations in membrane bioreactors (MBRs) are a top research issue. The aim of this work is to study the combined effect of colloids and soluble microbial products (SMPs) on membrane fouling. Two lab-pilot MBRs were investigated for treating two types of wastewater (wwt), synthetic and domestic. Transmembrane pressure (TMP), SMP, particle size distribution and treatment efficiency were evaluated. Chemical Oxygen Demand (COD) removal and nitrification were successful for both kinds of sewage reaching up to 95–97% and 100%, respectively. Domestic wwt presented 5.5 times more SMP proteins and 11 times more SMP carbohydrates compared to the synthetic one. In contrast, synthetic wwt had around 20% more colloids in the mixed liquor with a size lower than membrane pore size (<400 nm) than domestic. Finally, the TMP at 36 days reached 16 kPa for synthetic wwt and 11 kPa for domestic. Therefore, synthetic wwt, despite its low concentration of SMPs, caused severe membrane fouling compared to domestic, a result that is attributed to the increased concentration of colloids. Consequently, the quantity of colloids and possibly their special characteristics play decisive and more important roles in membrane fouling compared to the SMP—a novel conclusion that can be used to mitigate membranes fouling.

scholarly journals Effects of Pore Additives on Deep Eutectic Solvent Immobilization for CO₂/N₂ Gas Separation Using Supported Deep Eutectic Solvent Membranes

2021 ◽  
Vol 25 (2) ◽  
pp. 1-14
Author(s):  
Amira Mohd Nasib ◽  
Nora Jullok ◽  
Mohd Irfan Hatim Mohamad Dzahir ◽  
Patricia Luis ◽  
Bart Van Der Bruggen
Keyword(s):  
Polyvinylidene Fluoride ◽  
Gas Flow ◽  
Choline Chloride ◽  
Deep Eutectic Solvent ◽  
Gravimetric Method ◽  
Transmembrane Pressure ◽  
Hydrogen Bond Donor ◽  
Membrane Pore ◽  
Membrane Pores ◽  
Carbon Dioxide Co2

This work analyses the effect of two different pore additives focusing on polyethylene glycol (PEG) and lithium chloride (LiCl) at different concentrations on the immobilization of a deep eutectic solvent (DES) in a polyvinylidene fluoride-co-polytetrafluoroethylene (PVDF-co-PTFE) membrane. Two compounds were chosen to synthesized the DES; choline chloride as halide salt and ethylene glycol as a hydrogen bond donor.  The DES was impregnated onto the membrane pores by applying a vacuum-based technique. The membranes were prepared via phase inversion by means of immersion precipitation. For characterization purposes, scanning electron microscopy (SEM-EDX) was used to analyse the morphology of the supported- DES-membranes together with energy dispersive X-ray spectrometry. The gravimetric method was applied to calculate the porosity, while the membrane performance for carbon dioxide (CO2) permeation and separation was assessed to determine the capability of the DES-impregnated membrane. The outcomes demonstrating that the highest loading of DES in the membrane support was obtained when 3 wt% PEG was added into the polymer solution with a porosity of 70.5%. The CO2 permeability and the CO2/N2 selectivity achieved using the synthesized membrane are 2.81 x 106 barrer and 3.46, respectively, when working with a transmembrane pressure of 1.1 bar and a temperature of 25ᵒC at 200 cm3 /min of gas flow rate. The results showed that additional of PEG as a pore additives able to load the highest DES in the membrane pore and resulted the best CO2 permeability and the CO2/N2 selectivity.

Sign in / Sign up

Export Citation Format

Share Document