Water Breakthrough Pressure Research Articles

Electrospun Fibrous Membranes with Super-large-strain Electric Superhydrophobicity.

Large-strain elastic superhydrophobicity is highly desirable for its enhanced use performance and functional reliability in mechanically dynamic environments, but remains challenging to develop. Here we have, for the first time, proven that an elastic fibrous membrane after surface hydrophobization can maintain superhydrophobicity during one-directional (uniaxial) stretching to a strain as high as 1500% and two-direction (biaxial) stretching to a strain up to 700%. The fibrous membrane can withstand at least 1,000 cycles of repeated stretching without losing the superhydrophobicity. Stretching slightly increases the membrane air permeability and reduces water breakthrough pressure. It is highly stable in acid and base environments. Such a permeable, highly-elastic superhydrophobic membrane may open up novel applications in membrane separation, healthcare, functional textile and energy fields.

Carbon–silica composite nanofiber membrane for high flux separation of water-in-oil emulsion – Performance study and fouling mechanism

Abstract A flexible, hydrophobic and oleophilic carbon nanofiber membrane was prepared from electrospinning for cross-flow filtration of water-in-oil emulsion under various operating conditions. Experimental results show that the membrane has a high throughput of clean oil at low pressure. Furthermore, the membrane performance in terms of permeate flux was governed by the operating pressure and cross-flow velocity. The membrane has a water breakthrough pressure of 0.206 bar under constant cross-flow velocity. The investigation of membrane fouling mechanisms using pore blocking models and resistance model reveals that the membrane experiences either of external or internal fouling or a combination of both under different operating conditions. Using the contour plot analysis, it was suggested that the optimum operating conditions for the membrane to perform efficiently shall be at high cross-flow velocity and at low pressure (between 0.07 and 0.206 bar).

Liquid water breakthrough pressure through gas diffusion layer of proton exchange membrane fuel cell

The dynamic behavior of liquid water transport through the gas diffusion layer (GDL) of the proton exchange membrane fuel cell is studied with an ex-situ approach. The liquid water breakthrough pressure is measured in the region between the capillary fingering and the stable displacement on the drainage phase diagram. The variables studied are GDL thickness, PTFE/Nafion content within the GDL, GDL compression, the inclusion of a micro-porous layer (MPL), and different water flow rates through the GDL. The liquid water breakthrough pressure is observed to increase with GDL thickness, GDL compression, and inclusion of the MPL. Furthermore, it has been observed that applying some amount of PTFE to an untreated GDL increases the breakthrough pressure but increasing the amount of PTFE content within the GDL shows minimal impact on the breakthrough pressure. For instance, the mean breakthrough pressures that have been measured for TGP-060 and for untreated (0 wt.% PTFE), 10 wt.% PTFE, and 27 wt.% PTFE were 3589 Pa, 5108 Pa, and 5284 Pa, respectively.

Microfluidic Capillary Separation and Real-Time Spectroscopic Analysis of Specific Components from Multiphase Mixtures

We present a technique of phase separation suitable for microfluidic systems and demonstrate its efficient integration with a microfluidic optical cell for performing real-time spectrometric measurements on one specific phase from a mixture. We demonstrate that efficient and robust phase separation based on capillarity is possible within a microfluidic chip using either microfabricated capillary channels in polydimethylsiloxane (PDMS) or oil-wet fluoropolymer membranes, allowing for extraction of either the continuous or of the dispersed phases from a multiphase mixture. We analyze the dependence of phase separation efficiency on the operating parameters of the device and observe the presence of a hysteresis cycle during pressure sweeps above a water breakthrough pressure (P(b)); we also observe and analyze the reversibility of the oil-wet state of the membrane upon pressure reduction below a reset pressure (P(r) < P(b)). We test the capillary separation method extensively with several types of organic/water mixtures and emulsions and derive criteria for design and operation of a robust microfluidic capillary separator. As an example of monitoring application we describe the design and manufacturing of a microfluidic spectrometer cell optimized for fast response time, which was used to analyze the oil extracted from an oil/water emulsion using a capillary separator. The complete separator-sensor system is characterized in terms of response and cleanup times to instantaneous changes in the dye concentration of the phase of interest.

Hydrophobic inorganic membranes for water/gas separation

Macroporous or mesoporous hydrophobic inorganic membranes are prepared by a simple one-pot synthesis method coupling the sol–gel process with fluorinated silanes as precursors and the use of alumina powders as fillers. The porosity of these intrinsically hydrophobic membranes can be tuned by the particle size distribution of the dispersed alumina powder. These membranes developed for water/gas separation applications are characterized in term of gas permeance and water breakthrough pressure. A value of air permeance equal to 1800 L min−1 bar−1 m−2 associated with a water breakthrough pressure larger than 10 bar are measured for the effective sample.

Control of phenyl-group site introduced on the graft chain for hydrophobic interaction chromatography

A phenyl group was appended to the epoxy-group-containing polymer chain grafted onto the pore surface of a porous hollow-fiber membrane for hydrophobic interaction chromatography. For introduction of the phenyl group at a density sufficient for protein collection, glycidyl methacrylate (GMA) grafted membrane was immersed in 1 M phenol aqueous solution whose pH ranged from 9 to 13. A bovine serum albumin (BSA) buffer solution containing 2 M (NH 4) 2SO 4 was forced to permeate through the resultant porous hydrophobic membrane (Ph fiber). The Ph fiber prepared at a lower pH provided a higher elution percentage of BSA when elution was performed with an (NH 4) 2SO 4-free buffer. Introduction of the phenyl group at a high density onto the upper part of the shrinking graft layer at a higher pH was demonstrated based on the determination of water breakthrough pressure of the dried Ph fiber, resulting in a lower elution percentage of BSA.