On the Theory of Peptization

Sen, K. C.

doi:10.1021/j150258a006

Cited by 6 publications

(5 citation statements)

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“…Furthermore, all the data in the presence of glycerol (a weakly acidic material) fall along a common curve (figure 4) even at a glycerol to indium ratio of 100 moles to 1, and it thus appears that hydroxyl-ion adsorption is not appreciable in the presence of this polyhydric alcohol (see also table 1). Since indium hydroxide shows no tendency to be peptized by hydroxyl ion in the region mentioned above in the absence of such polyhydroxy compounds ( 12), it appears that these data support the contentions of Sen (17,19) that such compounds by their own adsorption on the hydrous oxide particles prevent agglomeration and thereby permit enhanced hydroxyl-ion adsorption with resultant formation of a negative sol.…”

Section: Discussionsupporting

confidence: 58%

“…Such effects were originally ascribed to the formation of complexes between the metal ion and the added non-electrolyte (5, 7, 13), although Graham (5) also recognized the presence of colloidal oxide particles. It is now believed, however, that in most instances the hydrous oxide or hydroxide is peptized by the excess hydroxyl ion from the added base in the presence of the polyhydroxy compounds (3,9,10,14,15,(17)(18)(19)(20)(21), for such solutions contain negatively charged colloidal particles (17,21) and have the same conductivities as suspensions formed in the absence of the nonelectrolytes (2). On the other hand, evidence has been presented for complex formation in the cases of copper (22,23), bismuth (8), and zirconium (1).…”

Section: Introductionmentioning

confidence: 99%

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Contributions to the Chemistry of Indium. IV. The Effects of Certain Poly-hydroxy Non-electrolytes upon the Precipitation of Hydrous Indium Hydroxide.

Moeller¹

1941

J. Phys. Chem.

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Section: Discussionsupporting

confidence: 58%

Section: Introductionmentioning

confidence: 99%

Contributions to the Chemistry of Indium. IV. The Effects of Certain Poly-hydroxy Non-electrolytes upon the Precipitation of Hydrous Indium Hydroxide.

Moeller¹

1941

J. Phys. Chem.

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“…Although tartaric acid currently features in some industrial scale anodization baths as reported in a patent on an adaptation of the sulfuric acid anodization process that incorporates tartaric acid [365] as the tartaric-sulfuric acid (TSA) anodization process, to the best of the authors' knowledge tartaric acid has not been reported as a component of anodized aluminum sealing baths. In the light of the effects of tartaric acid and tartrates on the structure evolution of alumina [373] and as a peptizing agent [374][375][376], we posit the plausible emergence of tartaric acid and tartrates in future sealing bath compositions especially as research efforts move towards one-pot anodization and sealing strategies.…”

Section: One Pot Anodization and Sealingmentioning

confidence: 99%

The Sealing Step in Aluminum Anodizing: A Focus on Sustainable Strategies for Enhancing Both Energy Efficiency and Corrosion Resistance

2020

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Increasing demands for environmental accountability and energy efficiency in industrial practice necessitates significant modification(s) of existing technologies and development of new ones to meet the stringent sustainability demands of the future. Generally, development of required new technologies and appropriate modifications of existing ones need to be premised on in-depth appreciation of existing technologies, their limitations, and desired ideal products or processes. In the light of these, published literature mostly in the past 30 years on the sealing process; the second highest energy consuming step in aluminum anodization and a step with significant environmental impacts has been critical reviewed in this systematic review. Emphasis have been placed on the need to reduce both the energy input in the anodization process and environmental implications. The implications of the nano-porous structure of the anodic oxide on mass transport and chemical reactivity of relevant species during the sealing process is highlighted with a focus on exploiting these peculiarities, in improving the quality of sealed products. In addition, perspective is provided on plausible approaches and important factors to be considered in developing sealing procedures that can minimize the energy input and environmental impact of the sealing step, and ensure a more sustainable aluminum anodization process/industry.Coatings 2020, 10, 226 2 of 55 sealing methods. Furthermore, the applicability of another hitherto popular sealing process; chromate sealing, is currently limited to essential parts in the aerospace industry due to toxicological, health, and environmental implications traced to Cr(VI) employed in the process [7][8][9][10][11][12][13][14][15][16]. On the other hand, the advantages of another industrially utilized sealing process; the nickel fluoride (cold) sealing process is limited by the toxicity of nickel salts which narrows its range of application, and introduces added costs due to post-sealing wastewater treatments and management [17][18][19][20]. Further efforts at sealing anodized aluminum at temperatures lower than that used in hydrothermal (high temperature) sealing, have led to much variety in the chemical constitution and operating temperatures of sealing baths [21]. On the basis of temperature at which the sealing step is carried out, sealing can be classified into three major categories; high temperature, mid-temperature, and room-temperature or cold sealing. In this work sealing at temperatures from 0 to 40 • C is classified as low temperature sealing, from ≥ 40 • C to 70 • C as intermediate or mid temperature sealing, and sealing at temperatures > 70 • C as high temperature sealing.

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“…The second step is the peptization, which starts immediately if acidified water is used, or after the post addition of acid. As the PZC is close to neutrality, acid addition results in protonation of surface hydroxyls, increasing the electrostatic surface charge density of the particles, and decreasing the interfacial tension [51][52][53]. This causes the fragmentation of primary particle agglomerates and also, as the colloidal particles bear a same sign electric charge, this prevents their re-aggregation because they mutually repel each other.…”

Section: Synthesis Of Stable Solsmentioning

confidence: 99%