A review of factors that affect contact angle and implications for flotation practice

Chau, T.T.; Bruckard, Warren J.; Koh, P.T.L.; Nguyen, Anh V.

doi:10.1016/j.cis.2009.07.003

Cited by 445 publications

(187 citation statements)

References 79 publications

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“…θ and thus the wettability depends on several factors, such as the chemical composition, the heterogeneity, the particle sizes and shapes, the roughness of the surface as well as on the porosity. 37,38 It should be kept in mind that the studied BPPs are composite materials consisting of two hydrophobic materials (graphite and polypropylene). The observed changes in the contact angle could be caused by water drop interaction with both materials.…”

Section: Resultsmentioning

confidence: 99%

Chemical Stability of Graphite-Polypropylene Bipolar Plates for the Vanadium Redox Flow Battery at Resting State

Satola

Kirchner

Komsiyska

et al. 2016

J. Electrochem. Soc.

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Current collectors called bipolar plates (BPP) are important elements within the conversion unit of the vanadium redox flow battery (VRFB). They are in direct contact with acidic electrolytes, containing vanadium species in different oxidation states. The influence of the state of charge (SOC) on the calendar aging of BPPs was examined. Graphite-polypropylene BPPs were immersed in positive and negative vanadium electrolytes at 0%, 20%, 80% and 100% SOC for 30, 90 and 190 days. H 2 gas evolution was observed as side reaction on the surface of the BPPs in the negative electrolyte. After electroless aging, scanning electron (SEM) and confocal microscopy measurements showed no significant changes in the surface morphology. The electrical conductivities of the BPPs were not affected significantly. However, contact angle (θ) measurements revealed that the positive electrolyte influenced the wettability of the BPPs. X-ray photoelectron (XP) spectroscopy showed progressing oxidation of the BPP surfaces in the positive electrolyte and adsorption or entrapment of vanadium ions in the pores at high SOC. Cyclic voltammograms (CV) provided evidence that the graphite was oxidized combined with an increase in effective surface area. ATR-FTIR measurements showed slight oxidation of pure polypropylene granulate in the positive electrolyte with 100% SOC. The increasing energy power supply from intermittent renewable energy sources requires a rapid introduction of efficient energy storages. One promising technology is the vanadium redox flow battery (VRFB), as it enables to scale the power and the storage capacity independently according to specific requirements.1,2 In addition the VRFB is characterized by a fast response time and long electrolyte cycle life.3 Each reaction unit in a VRFB stack is composed of two half-cells separated by a membrane consisting of an electrode in contact with a current collector called bipolar plate (BPP).2 In a battery stack the BPPs are "non-active" components that conduct current from one cell to the other. They physically separate adjacent cells from each other while staying in contact with acidic half-cell electrolytes containing vanadium species in different oxidation states on each side. 4 For brevity we call the V 2+ /V 3+ solution "negative electrolyte" and the VO 2+ /VO 2 + solution "positive electrolyte". While vanadium redox reactions mainly occur on the surfaces of the porous electrodes, they could also occur unintentionally on the surfaces of the BPPs. [5][6][7] Therefore, a good BPP should be characterized by a high chemical and mechanical stability, high electrical conductivity and impermeability to preclude leakage. 8 Metallic BPPs are usually not used in VRFB as they corrode in acidic environments and would need a protective layer.5,9,10 Therefore, graphite based BPPs are commonly used as they possess a good electrical conductivity and a better chemical stability. 4 However, pure graphite plates are not favored as BPPs due to their high weight and cost as well as low mechanical stre...

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Section: Resultsmentioning

confidence: 99%

Chemical Stability of Graphite-Polypropylene Bipolar Plates for the Vanadium Redox Flow Battery at Resting State

Satola

Kirchner

Komsiyska

et al. 2016

J. Electrochem. Soc.

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“…Wetting phenomena have been the subject of numerous experimental and theoretical studies since their understanding is related to many significant technological and industrial applications, including lubrication, coating, printing, waste water treatment, mineral processing, and microfluidics [1][2][3][4]. A widely used approach to characterization of wetting properties of surfaces involves the measurement of contact angles (CAs).…”

Section: Introductionmentioning

confidence: 99%

Droplet on a regularly patterned solid. Wenzel’s regime and meso-scale roughness

2015

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Abstract. The applicability of Wenzel's equation to describe a liquid droplet settled on the solid surface regularly patterned with rectangular prisms was examined by means of simulations of the droplet/surface system morphology and energetics. The droplet deposited on the meso-scale surface roughness (i.e. the droplet size was larger than the size of heterogeneities by about an order of magnitude) was considered. Several different approaches to the estimation of the contact angle were employed. The discrepancies between the results of simulated experimental measurements and the predictions based on the Wenzel equation were analyzed and discussed. The influence of three-phase contact line effects on the droplet morphology and the existence of metastable states was shown.

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“…The contact angle of the BCNW film, which was similar to that reported for MFC films (Rodionova et al, 2011) and TEMPO-oxidized cellulose nanofibres films (Fukuzumi et al, 2009), was characteristic of hydrophilic materials. As shown in Figure 6, the wettability of films was further increased when incorporating PEG into the system, as a consequence of the hydrophilic character of PEG and the increased roughness of the material, which is known to decrease contact angles for hydrophilic materials (Chau et al, 2009). On the contrary, as observed in Figure 6 and Table 3, the systems coated by annealed PLA electrospun nanostructured fibres or APTS, showed significantly higher contact angles of ca.…”

Section: Barrier Properties Of the Coated Systemsmentioning

confidence: 66%

Bacterial cellulose nanowhiskers to enhance the properties of plastics and bioplastics of interest in food packaging

Sanz¹

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A review of factors that affect contact angle and implications for flotation practice

Cited by 445 publications

References 79 publications

Chemical Stability of Graphite-Polypropylene Bipolar Plates for the Vanadium Redox Flow Battery at Resting State

Chemical Stability of Graphite-Polypropylene Bipolar Plates for the Vanadium Redox Flow Battery at Resting State

Droplet on a regularly patterned solid. Wenzel’s regime and meso-scale roughness

Bacterial cellulose nanowhiskers to enhance the properties of plastics and bioplastics of interest in food packaging

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