Contact angles of aluminosilicate clays as affected by relative humidity and exchangeable cations

Shang, Jianying; Flury, Markus; Harsh, James B.; Zollars, Richard L.

doi:10.1016/j.colsurfa.2009.10.013

Cited by 79 publications

(36 citation statements)

References 63 publications

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“…Indeed, the surfaces of many mineral dusts like quartz and feldspars are covered with hydroxyl groups, which render surfaces hydrophilic (Koretsky et al, 1997). Shang et al (2010) measured contact angles of water droplets on clay films and found, for illites, a dependence of contact angles on relative humidity and on the exchangeable cations: the contact angle of Ca-illite sank from 28.3 to 21.6 • when RH was raised from 19 to 100 %. At 33 % RH, contact angles ranged between 23.3 and 34.2 • for illites saturated with different cations (Na, K, Mg or Ca).…”

Section: Arizona Test Dustmentioning

confidence: 99%

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Comparing contact and immersion freezing from continuous flow diffusion chambers

et al. 2016

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Abstract. Ice nucleating particles (INPs) in the atmosphere are responsible for glaciating cloud droplets between 237 and 273 K. Different mechanisms of heterogeneous ice nucleation can compete under mixed-phase cloud conditions. Contact freezing is considered relevant because higher ice nucleation temperatures than for immersion freezing for the same INPs were observed. It has limitations because its efficiency depends on the number of collisions between cloud droplets and INPs. To date, direct comparisons of contact and immersion freezing with the same INP, for similar residence times and concentrations, are lacking. This study compares immersion and contact freezing efficiencies of three different INPs. The contact freezing data were obtained with the ETH CoLlision Ice Nucleation CHamber (CLINCH) using 80 µm diameter droplets, which can interact with INPs for residence times of 2 and 4 s in the chamber. The contact freezing efficiency was calculated by estimating the number of collisions between droplets and particles. Theoretical formulations of collision efficiencies gave too high freezing efficiencies for all investigated INPs, namely AgI particles with 200 nm electrical mobility diameter, 400 and 800 nm diameter Arizona Test Dust (ATD) and kaolinite particles. Comparison of freezing efficiencies by contact and immersion freezing is therefore limited by the accuracy of collision efficiencies. The concentration of particles was 1000 cm −3 for ATD and kaolinite and 500, 1000, 2000 and 5000 cm −3 for AgI. For concentrations < 5000 cm −3 , the droplets collect only one particle on average during their time in the chamber. For ATD and kaolinite particles, contact freezing efficiencies at 2 s residence time were smaller than at 4 s, which is in disagreement with a collisional contact freezing process but in accordance with immersion freezing or adhesion freezing. With "adhesion freezing", we refer to a contact nucleation process that is enhanced compared to immersion freezing due to the position of the INP on the droplet, and we discriminate it from collisional contact freezing, which assumes an enhancement due to the collision of the particle with the droplet. For best comparison with contact freezing results, immersion freezing experiments of the same INPs were performed with the continuous flow diffusion chamber Immersion Mode Cooling chAmber-Zurich Ice Nucleation Chamber (IMCA-ZINC) for a 3 s residence time. In IMCA-ZINC, each INP is activated into a droplet in IMCA and provides its surface for ice nucleation in the ZINC chamber. The comparison of contact and immersion freezing results did not confirm a general enhancement of freezing efficiency for contact compared with immersion freezing experiments. For AgI particles the onset of heterogeneous freezing in CLINCH was even shifted to lower temperatures compared with IMCA-ZINC. For ATD, freezing efficiencies for contact and immersion freezing experiments were similar. For kaolinite particles, contact freezing became detectable at higher temperatures than imm...

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Section: Arizona Test Dustmentioning

confidence: 99%

“…Nanodroplets spread on the octahedral surface indicating a contact angle of 0 • . Shang et al (2010) measured a contact angle of about 18 • for water droplets on kaolinite films. This experimental value represents an averaged value over all kaolinite surfaces.…”

Section: Kaolinitementioning

confidence: 99%

Comparing contact and immersion freezing from continuous flow diffusion chambers

et al. 2016

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“…Contact angles of aluminosilicate clays are difficult to determine because they may vary with relative humidity and exchangeable cations. In addition, clays typically have small particle sizes that present measurement difficulties (Shang et al, 2010). Shang et al (2008) compared five different experimental methods to determine contact angles on smectite, kaolinite, illite, goethite, and hematite.…”

Section: Resultsmentioning

confidence: 99%

“…Shang et al (2008) compared five different experimental methods to determine contact angles on smectite, kaolinite, illite, goethite, and hematite. In Shang et al (2010), contact angles for Arizona smectite (SAz-1), Georgia kaolinite (KGa-1b), and illite (Morris No. 36) were measured under different conditions.…”

Section: Resultsmentioning

confidence: 99%

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Molecular modeling in support of CO2 sequestration and enhanced oil recovery.

Criscenti¹,

Bracco

2011

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Classical molecular dynamics simulations were used to investigate the formation of water droplets on two kaolinite surfaces: the gibbsite-like surface which is hydrophilic and the silica surface which is hydrophobic. Two methods for calculating contact angles were investigated in detail. The method of Giovambattista et al. was successful in calculating contact angles on both surfaces that compare well to the experimental data available. This is the first time that contact angles have been calculated for kaolinite surfaces from molecular simulations. This preliminary study provides the groundwork for investigating contact angles for more complex systems involving multiple fluids (water, CO 2 , oil) in contact with different minerals in the subsurface environment. 5 AcknowledgmentsWe want to thank Christopher Daub, a Postdoctoral Associate at Virginia Commonwealth University for sharing his insight on calculating contact angles from LAMMPS trajectory data and providing his FORTRAN code for making these calculations. We learned a great deal from his letter giving us an overview of the state of the art, and we used his code to educate us on the binning process for the liquid drop.

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Surface Tensiometry Approach to Characterize Cosmetic Products in the Beauty Sector

Rossi

Realdon

2021

Surface Science and Adhesion in Cosmetics

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Contact angles of aluminosilicate clays as affected by relative humidity and exchangeable cations

Cited by 79 publications

References 63 publications

Comparing contact and immersion freezing from continuous flow diffusion chambers

Comparing contact and immersion freezing from continuous flow diffusion chambers

Molecular modeling in support of CO2 sequestration and enhanced oil recovery.

Surface Tensiometry Approach to Characterize Cosmetic Products in the Beauty Sector

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