NF Membranes Characterisation: Relating Performance (flux and rejection) with Surface Properties (Contact Angle and Surface Free Energy)

AbstractThe surface free energy of Ca-montmorillonite has been determined from measurement of the contact angle of water on an oriented deposit immersed in n-alkanes; the oriented deposits were equilibrated at different relative humidities. These experiments provided the polar, γSP, and dispersive, γSD, components of the surface free energy γs. The results indicate that: (1) γs is mainly due to dispersive forces (γSD ≃ 145 mJ.m−2) and, to a lesser degree, polar forces (γSP ≃ 35 mJ.m−2). (2) The value of the apparent surface free energy of the clay, γα, tends towards that measured for water when the solid water content exceeds 50 wt%. (3) The sorption of water molecules substantially modifies the surface free energy of the solid; γs decreases from 180 mJ.m−2 to 60 mJ.m−2 when the water content increases from 0 to 50%. These results agree with other observations made on solids whose surface characteristics are similar to montmorillonite, i.e. micas, silicates and glasses. In addition, variations of γs with water content can be related to the hydration processes of smectites. Finally, these results show that the silicate no longer influences the surface properties when the montmorillonite water content exceeds 60%.

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Within-tree variations in the surface free energy of wood assessed by contact angle analysis

Wood Science and Technology ◽

10.1007/s00226-011-0407-1 ◽

2011 ◽

Vol 46 (1-3) ◽

pp. 287-298 ◽

Cited By ~ 14

Author(s):

Davide Rossi ◽

Sergio Rossi ◽

Hubert Morin ◽

Antonio Bettero

Keyword(s):

Contact Angle ◽

Free Energy ◽

Surface Free Energy ◽

Contact Angle Analysis

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Surface Free Energy Analysis of Natural and Modified Natural Rubber Latex Films by Contact Angle Method

Langmuir ◽

10.1021/la9816104 ◽

2000 ◽

Vol 16 (3) ◽

pp. 1407-1414 ◽

Cited By ~ 39

Author(s):

C. C. Ho ◽

M. C. Khew

Keyword(s):

Contact Angle ◽

Free Energy ◽

Natural Rubber ◽

Surface Free Energy ◽

Energy Analysis ◽

Natural Rubber Latex ◽

Latex Films ◽

Rubber Latex ◽

Angle Method ◽

Free Energy Analysis

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Surface Free Energy Components of Clay-Synthetic Humic Acid Complexes from Contact-Angle Measurements

Clays and Clay Minerals ◽

10.1346/ccmn.1991.0390106 ◽

1991 ◽

Vol 39 (1) ◽

pp. 43-49 ◽

Cited By ~ 23

Author(s):

Claire Jouany

Keyword(s):

Contact Angle ◽

Free Energy ◽

Humic Acid ◽

Surface Free Energy ◽

Angle Measurements ◽

Contact Angle Measurements ◽

Energy Components

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Hydrophobic and Oleophilic Filter Paper for Oil/Water Separation

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.798.385 ◽

2019 ◽

Vol 798 ◽

pp. 385-390

Author(s):

Sunisa Jindasuwan ◽

Sitthisuntorn Supothina

Keyword(s):

Contact Angle ◽

Free Energy ◽

Surface Free Energy ◽

Water Contact Angle ◽

Filter Paper ◽

Diesel Oil ◽

Selective Removal ◽

Water Contact ◽

Water Separation ◽

Filter Papers

The separation of oil from water is significance for environmental de-pollution application. To obtain selectivity of liquid, filter papers were coated to bear highly hydrophobic and oleophilic functionality that can allow only oils to pass through them. The coating solutions were prepared by mixing poly(methylhydro siloxane, PMHS) and fumed silica at various proportions. To determine an optimum coating condition, properties of the treated filter papers were investigated by measuring water contact angle and surface free energy, examining surface morphology and testing for selective removal of diesel oil from water. The optimum coating solution was at the PMHS:fumed silica weight ratio of 1.25:1.00. The treated filter paper exhibited high hydrophobicity with water contact angle of 142.80 ± 0.36 degrees and surface free energy of 0.78 mJ/m2. In addition, it exhibited high selective removal of diesel oil from water with oil absorption capacity of 2.3 g/g.

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