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Investigation of the polyvinyl alcohol stabilization mechanism and adsorption properties on the surface of ternary mixed nanooxide AST 50 (Al2O3-SiO2-TiO2).

Wiśniewska M, Ostolska I, Szewczuk-Karpisz K, Chibowski S, Terpiłowski K, Gun'ko VM, Zarko VI - J Nanopart Res (2015)

Bottom Line: Due to the nonionic character of the analyzed macromolecular compound, the polymer attendance has an insignificant effect on the AST 50 surface charge density.In turn, in an alkaline medium the mixed oxide suspensions exhibit the highest durability, which is a result of a large number of the negative charges on the AST 50 surface.The addition of PVA 100 significantly improves the suspension stability at pH 3 and 6; at higher pH value, the polymer presence does not influence the system durability.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiochemistry and Colloids Chemistry, Faculty of Chemistry, Maria Curie-Sklodowska University, M. Curie-Sklodowska Sq. 3, 20-031 Lublin, Poland.

ABSTRACT

A new adsorbent consisting of fumed, mixed alumina, silica, and titania in various proportions (AST 50) was investigated. The studied material was prepared by chemical vapor deposition method. The diameter of AST 50 primary particles was equal to about 51 nm which denotes that it can be classified as a nanomaterial. In the presented paper, the adsorption properties of polyvinyl alcohol on the ternary oxide were investigated. The polymer macromolecules were characterized by two different molecular weights and degree of hydrolysis. The polymer adsorption reaches the maximum at pH 3 and decreases with the solution pH rise. The reduction of the adsorbed PVA macromolecules is related to the electrostatic repulsion forces occurring in the studied system. The AST 50 point of zero charge (pHpzc) obtained from the potentiometric titration is equal to 4.7. Due to the nonionic character of the analyzed macromolecular compound, the polymer attendance has an insignificant effect on the AST 50 surface charge density. In the case of the adsorbent particles zeta potential, the obtained dependencies are different in the absence and presence of PVA. The shift of the slipping plane and displacement of the counter-ions from Stern layer by the adsorbed polymer chains have the greatest effect on the ζ potential value. The stability measurements indicate that the AST 50 suspensions in the presence of the background electrolyte at pH 3 and 6 are unstable. In turn, in an alkaline medium the mixed oxide suspensions exhibit the highest durability, which is a result of a large number of the negative charges on the AST 50 surface. The addition of PVA 100 significantly improves the suspension stability at pH 3 and 6; at higher pH value, the polymer presence does not influence the system durability. It is related to the steric and electrosteric stabilization of the colloidal particles by the adsorbed polyvinyl alcohol macromolecules.

No MeSH data available.


Related in: MedlinePlus

Comparison of the potentiometric curves for different weights of PVA at a concentration of 100 ppm
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Fig7: Comparison of the potentiometric curves for different weights of PVA at a concentration of 100 ppm

Mentions: The potentiometric data obtained for the systems containing PVA at different concentrations (but the same molecular weight) point out that the polymer concentration has no essential impact on the AST 50 surface charge density. The curves are almost overlapping for both PVA 72 and PVA 100. This comes from the presence of an insignificantly larger number of the polymer functional groups with the concentration growth. Some conclusions on the influence of the PVA molecular weight on the AST 50 σ0 values can be drawn from the dependencies present in Fig. 7. The effect associated with the increase in the adsorbent surface charge density observed above pH 8 is considerably smaller for the higher molecular weight polymer. Such a behavior can be explained by the presence of a larger number of the ionized acetic groups belonging to the PVA 100 chains (with regard to PVA 72). The increase in the polymer charged functional groups contributes to a higher number of the negative charges located near the solid surface. Hence, the influence of the positive surface charge induction is smaller on account of the negatively charged acetic groups presence in the AST 50 by-surface layer.Fig. 7


Investigation of the polyvinyl alcohol stabilization mechanism and adsorption properties on the surface of ternary mixed nanooxide AST 50 (Al2O3-SiO2-TiO2).

Wiśniewska M, Ostolska I, Szewczuk-Karpisz K, Chibowski S, Terpiłowski K, Gun'ko VM, Zarko VI - J Nanopart Res (2015)

Comparison of the potentiometric curves for different weights of PVA at a concentration of 100 ppm
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4300396&req=5

Fig7: Comparison of the potentiometric curves for different weights of PVA at a concentration of 100 ppm
Mentions: The potentiometric data obtained for the systems containing PVA at different concentrations (but the same molecular weight) point out that the polymer concentration has no essential impact on the AST 50 surface charge density. The curves are almost overlapping for both PVA 72 and PVA 100. This comes from the presence of an insignificantly larger number of the polymer functional groups with the concentration growth. Some conclusions on the influence of the PVA molecular weight on the AST 50 σ0 values can be drawn from the dependencies present in Fig. 7. The effect associated with the increase in the adsorbent surface charge density observed above pH 8 is considerably smaller for the higher molecular weight polymer. Such a behavior can be explained by the presence of a larger number of the ionized acetic groups belonging to the PVA 100 chains (with regard to PVA 72). The increase in the polymer charged functional groups contributes to a higher number of the negative charges located near the solid surface. Hence, the influence of the positive surface charge induction is smaller on account of the negatively charged acetic groups presence in the AST 50 by-surface layer.Fig. 7

Bottom Line: Due to the nonionic character of the analyzed macromolecular compound, the polymer attendance has an insignificant effect on the AST 50 surface charge density.In turn, in an alkaline medium the mixed oxide suspensions exhibit the highest durability, which is a result of a large number of the negative charges on the AST 50 surface.The addition of PVA 100 significantly improves the suspension stability at pH 3 and 6; at higher pH value, the polymer presence does not influence the system durability.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiochemistry and Colloids Chemistry, Faculty of Chemistry, Maria Curie-Sklodowska University, M. Curie-Sklodowska Sq. 3, 20-031 Lublin, Poland.

ABSTRACT

A new adsorbent consisting of fumed, mixed alumina, silica, and titania in various proportions (AST 50) was investigated. The studied material was prepared by chemical vapor deposition method. The diameter of AST 50 primary particles was equal to about 51 nm which denotes that it can be classified as a nanomaterial. In the presented paper, the adsorption properties of polyvinyl alcohol on the ternary oxide were investigated. The polymer macromolecules were characterized by two different molecular weights and degree of hydrolysis. The polymer adsorption reaches the maximum at pH 3 and decreases with the solution pH rise. The reduction of the adsorbed PVA macromolecules is related to the electrostatic repulsion forces occurring in the studied system. The AST 50 point of zero charge (pHpzc) obtained from the potentiometric titration is equal to 4.7. Due to the nonionic character of the analyzed macromolecular compound, the polymer attendance has an insignificant effect on the AST 50 surface charge density. In the case of the adsorbent particles zeta potential, the obtained dependencies are different in the absence and presence of PVA. The shift of the slipping plane and displacement of the counter-ions from Stern layer by the adsorbed polymer chains have the greatest effect on the ζ potential value. The stability measurements indicate that the AST 50 suspensions in the presence of the background electrolyte at pH 3 and 6 are unstable. In turn, in an alkaline medium the mixed oxide suspensions exhibit the highest durability, which is a result of a large number of the negative charges on the AST 50 surface. The addition of PVA 100 significantly improves the suspension stability at pH 3 and 6; at higher pH value, the polymer presence does not influence the system durability. It is related to the steric and electrosteric stabilization of the colloidal particles by the adsorbed polyvinyl alcohol macromolecules.

No MeSH data available.


Related in: MedlinePlus