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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.

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Related in: MedlinePlus

Adsorption isotherms of PVA 100 on the AST 50 surface at various solution pH values
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Fig3: Adsorption isotherms of PVA 100 on the AST 50 surface at various solution pH values

Mentions: The adsorption isotherms of different weights of polyvinyl alcohol on the AST 50 surface as a function of the three investigated solution pH values are shown in Figs. 2 and 3. The course of these dependencies indicates that the adsorption amount decrease is observed when the solution pH grows. This is related to the mixed oxide surface charge changes. The analysis of AST 50 composition leads to the conclusion that at pH 3 the majority of the nanooxide surface groups are positively charged. The hydroxyl groups occurring on the oxide materials surface exhibit the amphoteric nature. For the aqueous solutions, the most important in the charge formation process are hydrogen and hydroxyl ions which can interact with the surface active groups in the following ways (Janusz et al. 1997):2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\equiv {\rm MOH}_{2}^{ + } \leftrightarrow \equiv {\rm MOH} + {\rm H}^{ + }$$\end{document}≡MOH2+↔≡MOH+H+3\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\equiv MOH + OH^{ - } \leftrightarrow \equiv MO^{ - } + H_{2} O$$\end{document}≡MOH+OH-↔≡MO-+H2O4\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\equiv {\rm M}_{1} - {\rm O}({\rm H}) - {\rm M}_{2} \equiv \leftrightarrow \equiv {\rm M}_{1} \left( {\rm O}^{ - } \right) - {\rm M}_{2} \equiv + \,{\rm H}^{ + },$$\end{document}≡M1-O(H)-M2≡↔≡M1O--M2≡+H+,Fig. 2


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)

Adsorption isotherms of PVA 100 on the AST 50 surface at various solution pH values
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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

Fig3: Adsorption isotherms of PVA 100 on the AST 50 surface at various solution pH values
Mentions: The adsorption isotherms of different weights of polyvinyl alcohol on the AST 50 surface as a function of the three investigated solution pH values are shown in Figs. 2 and 3. The course of these dependencies indicates that the adsorption amount decrease is observed when the solution pH grows. This is related to the mixed oxide surface charge changes. The analysis of AST 50 composition leads to the conclusion that at pH 3 the majority of the nanooxide surface groups are positively charged. The hydroxyl groups occurring on the oxide materials surface exhibit the amphoteric nature. For the aqueous solutions, the most important in the charge formation process are hydrogen and hydroxyl ions which can interact with the surface active groups in the following ways (Janusz et al. 1997):2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\equiv {\rm MOH}_{2}^{ + } \leftrightarrow \equiv {\rm MOH} + {\rm H}^{ + }$$\end{document}≡MOH2+↔≡MOH+H+3\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\equiv MOH + OH^{ - } \leftrightarrow \equiv MO^{ - } + H_{2} O$$\end{document}≡MOH+OH-↔≡MO-+H2O4\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\equiv {\rm M}_{1} - {\rm O}({\rm H}) - {\rm M}_{2} \equiv \leftrightarrow \equiv {\rm M}_{1} \left( {\rm O}^{ - } \right) - {\rm M}_{2} \equiv + \,{\rm H}^{ + },$$\end{document}≡M1-O(H)-M2≡↔≡M1O--M2≡+H+,Fig. 2

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