Contact angle and adsorption behavior of carboxylic acids on α-Al2O3 surfaces

Megı́as-Alguacil, David; Tervoort, Elena; Cattin, Cyrill; Gauckler, Ludwig J.

doi:10.1016/j.jcis.2010.09.087

Cited by 58 publications

(58 citation statements)

References 40 publications

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“…The weight loss of the ATZS3 and ATZS5 samples is seen to be more or less constant till 1400 ℃. The ZrSiO 4 decomposes into ZrO 2 and SiO 2 over 1450 ℃ during reaction-sintering process; to form mullite [28,29], ZrTiO 4 , and Al 2 TiO 5 based porous ceramics with an Al 2 O 3 source at low temperature, the mechanism is explained as follows [33,34]: 2(ZrO 2 + SiO 2 ) + 3Al 2 O 3 →3Al 2 O 3 ·2SiO 2 + 2ZrO 2 (6) ZrO 2 +TiO 2 →ZrTiO 4 (7) The main phase of the AT is Al 2 TiO 5 , while traces of rutile (3.5%) and corundum (5.86%) are also identified, as shown in Fig. 8.…”

Section: Resultsmentioning

confidence: 99%

“…Figure 3 establishes the air content and average bubble size of the Al 2 O 3 -TiO 2 equimolar suspension versus different volume percentage of the added suspension ZrO 2 -SiO 2 . High-volume wet foam with air content up to 95% is foamed, which strongly indicates the air bubble stabilization, due to the particle attachment at the air-water interface [27,28]. The average bubble size was measured, and upon the addition of 10 vol% ZrO 2 -SiO 2 suspension, the bubble size suddenly decreases; this may be because of increment in viscosity of the suspension due to a higher particle concentration.…”

Section: Drying/sinteringmentioning

confidence: 99%

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Al2O3–TiO2/ZrO2–SiO2 based porous ceramics from particle-stabilized wet foam

et al. 2017

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Abstract:The porous ceramics based on Al 2 O 3 -TiO 2 /ZrO 2 -SiO 2 from particle-stabilized wet foam by direct foaming were discussed. The initial Al 2 O 3 -TiO 2 suspension was prepared by adding TiO 2 suspension to partially hydrophobized colloidal Al 2 O 3 suspension with equimolar amount, to form Al 2 TiO 5 on sintering. The secondary ZrO 2 -SiO 2 suspension was prepared using the equimolar composition, and to obtain ZrSiO 4 , ZrTiO 4 , and mullite phases in the sintered samples, the secondary suspension was blended into the initial suspension at 0, 10, 20, 30, and 50 vol%. The wet foam exhibited an air content up to 87%, Laplace pressure from 1.38 to 2.23 mPa, and higher adsorption free energy at the interface of approximately 5.8×10 8 to 7.5×10 8 J resulting an outstanding foam stability of 87%. The final suspension was foamed, and the wet foam was sintered from 1400 to 1600 ℃ for 1 h. The porous ceramics with pore size from 150 to 400 μm on average were obtained. The phase identification was accomplished using X-ray diffraction (XRD), differential thermal analysis (DTA), and thermogravimetric analysis (TGA), and microstructural analysis was performed using field emission scanning electron microscopy (FESEM).

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Section: Resultsmentioning

confidence: 99%

Section: Drying/sinteringmentioning

confidence: 99%

Al2O3–TiO2/ZrO2–SiO2 based porous ceramics from particle-stabilized wet foam

et al. 2017

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“…Karaman and Megias-Alguacil observed changes in the contact angle after the adsorption of organic carboxylates on alumina surfaces [44,45]. Desset-Brèthes also showed adsorption using UV-vis spectroscopy and recognised the combination of carbon skeleton and strong complexing groups required to produce the highest affinity of the carboxylate ligands onto alumina surfaces at the pH near their pK a values [46].…”

Section: Bridging Mechanismmentioning

confidence: 95%

Adsorption of sodium hexanoate on α-alumina

Lee¹,

Welbourn²,

Clarke³

et al. 2013

Journal of Colloid and Interface Science

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a b s t r a c tNeutron reflection and adsorption isotherm measurements have been used to study the adsorption behaviour of hexanoic acid onto a-alumina surfaces. Importantly, the pH dependence of the behaviour has been characterised with a pronounced maximum in adsorption identified at a pH of approximately 5, close to the pK a of the acid. The adsorbed layer is identified as a bilayer, which is reasonable given the hydrophilic nature of both side of the layer, and has a thickness of 13 Å, suggesting significant extent of interdigitation. At pH 5, the layer has much lower extent of hydration relative to the higher pH of 7, consistent with the increased total adsorption at pH 5. A number of different mechanisms for the binding of the hexanoic acid to the surface are considered. The experimental data, combined with calculations using equilibrium/binding constants of the surface and ligands, indicates that a ligand exchange reaction may be the most significant mechanism.

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“…Nevertheless, MegiasAlguacil et al 18 showed the modifier's concentration scales with the contact angle (θ e ) up to a maximum value. Hence, very high concentrations of acids can lead to θe decrease.…”

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confidence: 99%

“…Above a critical amount, the acid molecule adsorption is carried out in a multilayer fashion, which reduces the hydrophobizing effect as the polar groups of the secondary layers add charge to the system (rendering it more hydrophilic). Moreover, the acid concentration at the θe maximum value is not always used in practice due to the high viscosity of such systems 14,18 . Thus, the only approach to enhance the adsorption process of acid molecules at the alumina surface, given a fixed concentration and chain-length, is to use molecules with lower pKa values.…”

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confidence: 99%

In situ α-alumina hydrophobization dynamics at acid pH: effectiveness limitations of short-chain amphiphilic molecules

et al. 2013

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The present work highlights that α-alumina hydrophobicity (attained by the in situ modification of its surface properties with water soluble organic monoacids) cannot be increased by using molecules with low acidity (pKa) values due to the alumina zeta potential profile at pHs below approximately 4. In order to certify this statement, the effects of short-chain fatty acids and fluorinated ones on the alumina contact angle (θe) with water were analyzed. It is also pointed out that the θe values derived from the experiments carried out using fluorinated acids are the highest possible when monoacid surfactants are added in α-alumina suspensions in acidic pH. This result indicates that there is another constraint to the in situ hydrophobization procedure, which was not previously elucidated or fully settled in literature.

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Contact angle and adsorption behavior of carboxylic acids on α-Al2O3 surfaces

Cited by 58 publications

References 40 publications

Al2O3–TiO2/ZrO2–SiO2 based porous ceramics from particle-stabilized wet foam

Al2O3–TiO2/ZrO2–SiO2 based porous ceramics from particle-stabilized wet foam

Adsorption of sodium hexanoate on α-alumina

In situ α-alumina hydrophobization dynamics at acid pH: effectiveness limitations of short-chain amphiphilic molecules

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