A comparison of contact angle measurement techniques applied to highly porous catalyst supports

Nowak, Emilia; Combes, Gary; Stitt, E. Hugh; Pacek, Andrzej W.

doi:10.1016/j.powtec.2012.08.032

Cited by 86 publications

(62 citation statements)

References 46 publications

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“…The first weight loss below 200°C corresponds to the removal of residual water; this was less than 4% to 6%. In the second stage, the PSU starts to be decomposed at about 380°C . Due to PPS decomposition, weight loss at temperatures higher than 498°C occurs in the third stage .…”

Section: Resultsmentioning

confidence: 99%

“…The first weight loss below 200 C corresponds to the removal of residual water; this was less than 4% to 6%. In the second stage, the PSU starts to be decomposed at about 380 C. 30 Due to PPS decomposition, weight loss at temperatures higher than 498 C occurs in the third stage. 31 The fresh Zirfon PERL separator exhibits high stability, but of which the other separators decreases as the ratio of ZrO 2 in the separator increases, as shown in Figure 3A.…”

Section: Characterization Of the Separatormentioning

confidence: 99%

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The synthesis of a Zirfon‐type porous separator with reduced gas crossover for alkaline electrolyzer

et al. 2019

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Summary The rapid expansion of renewable energy sources presents a great challenge to balance the electric grid due to their intermittent and volatile nature. The surplus energy generation cannot be used or sold so that it is curtailed in order to maintain the grid balance. The excess power can be converted into a gaseous energy carrier, hydrogen via power‐to‐gas technology. Alkaline water electrolysis can be operated in a dynamic mode using renewable energy sources on a large scale. However, the risk of gas crossover across a porous separator rapidly increases when the electrolyzer operates at a low partial load or at high pressure, leading to efficiency loss and a safety issue. The commercial porous separator Zirfon PERL, which is composed of 85 wt.% zirconia nanoparticles and 15 wt.% polysulfone, exhibits a satisfactory bubble point pressure performance of approximately 2.5 bar and ionic resistance of 0.3 Ω cm2. However, the Zirfon PERL separator exhibits a high hydrogen permeability value of 20 × 10−12 mol cm−1 bar−1 sec−1 due to its large average pore size of 130 nm, resulting in a limited dynamic range of the electrolyzer. Therefore, it is necessary to develop a porous separator with reduced gas crossover. In this study, we synthesize a porous ZrO2/polysulfone composite separator by varying the amount of ZrO2 (75‐85 wt.%) via the film‐casting method. The 75 wt.% ZrO2/25 wt.% polysulfone composite separator, which contains a low amount of ZrO2, shows a high bubble point pressure of 3.8 bar, a low ionic resistance of 0.3 Ω cm2, and are reduced hydrogen permeability of 4.2 × 10−12 mol cm−1 bar−1 sec−1 compared with that of Zirfon PERL separator. The enhanced performance of this separator is attributed to the reduced average pore size of around 70 nm and high surface wettability with a contact angle of 75°. This result will help alkaline electrolyzer systems be operated as more controllable loads.

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Section: Resultsmentioning

confidence: 99%

Section: Characterization Of the Separatormentioning

confidence: 99%

The synthesis of a Zirfon‐type porous separator with reduced gas crossover for alkaline electrolyzer

et al. 2019

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“…Oscillation of droplet surfaces occurs, if surface tension and inertia force are competing due to size and liquid volume . In literature, two types of oscillation with pinned or mobile contact lines are described . For the second case, oscillation with a mobile contact line, the radius of the droplet, meaning the phase boundary between liquid, solid object, and surrounding gas phase is moving as well.…”

Section: Resultsmentioning

confidence: 99%

Novel electrodynamic oscillation technique enables enhanced mass transfer and mixing for cultivation in micro‐bioreactor

Frey

Vorländer

Rasch

et al. 2019

Biotechnology Progress

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Micro‐bioreactors (MBRs) have become an indispensable part for modern bioprocess development enabling automated experiments in parallel while reducing material cost. Novel developments aim to further intensify the advantages as dimensions are being reduced. However, one factor hindering the scale‐down of cultivation systems is to provide adequate mixing and mass transfer. Here, vertical oscillation is demonstrated as an effective method for mixing of MBRs with a reaction volume of 20 μL providing adequate mass transfer. Electrodynamic exciters are used to transduce kinetic energy onto the cultivation broth avoiding additional moving parts inside the applied model MBR. The induced vertical vibration leads to oscillation of the liquid surface corresponding to the frequency and displacement. On this basis, the resonance frequency of the fluid was identified as the most decisive factor for mixing performance. Applying this vertical oscillation method outstanding mixing times below 1 s and exceptionally high oxygen transport with volumetric mass transfer coefficients (kLa) above 1,000/hr can be successfully achieved and controlled. To evaluate the applicability of this vertical oscillation mixing for low volume MBR systems, cultivations of Escherichia coli BL21 as proof‐of‐concept were performed. The dissolved oxygen was successfully online monitored to assure any avoidance of oxygen limitations during the cultivation. The here presented data illustrate the high potential of the vertical oscillation technique as a flexible measure to adapt mixing times and oxygen transfer according to experimental demands. Thus, the mixing technique is a promising tool for various biological and chemical micro‐scale applications still enabling adequate mass transfer.

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“…[10] The subject become even more pressing considering that even slight changes in the morphology and oxide content are known to drastically affect the hydrophilicity of the silicon oxide thin films, [11] which depending on the deposition technology employed can show moderate to high hydrophilicity with contact angles with pure water varying between almost 80 and less than 10 degrees. [12,13] 2. Experimental Two chromonic lyotropic liquid crystals were tested: Cromolyn (sodium cromoglycate) and Sunset Yellow FCF (disodium 6-hydroxy-5-[(4-sulphonatophenyl) azo]naphthalene-2-sulphonate) (Sigma-Aldrich, Spain).…”

Section: Introductionmentioning

confidence: 99%

Aligning lyotropic liquid crystals with silicon oxides

et al. 2015

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A detailed study on optimal alignment layers and alignment properties has been carried out for the water-soluble lyotropic liquid crystals Sunset Yellow and Cromolyn. Two different inorganic layers, SiO 2 and SiOx, were deposited onto indium tin oxide-coated glasses and tested in sandwich-like cells for both lyotropic liquid crystals. Both layers could be conditioned to align the lyotropic liquid crystals producing excellent aligned cells.

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A comparison of contact angle measurement techniques applied to highly porous catalyst supports

Cited by 86 publications

References 46 publications

The synthesis of a Zirfon‐type porous separator with reduced gas crossover for alkaline electrolyzer

The synthesis of a Zirfon‐type porous separator with reduced gas crossover for alkaline electrolyzer

Novel electrodynamic oscillation technique enables enhanced mass transfer and mixing for cultivation in micro‐bioreactor

Aligning lyotropic liquid crystals with silicon oxides

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