title: Investigation of the polyvinyl alcohol stabilization mechanism and adsorption properties on the surface of ternary mixed nanooxide AST 50 (Al2O3-SiO2-TiO2).
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 theζpotential 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.
authors.affiliation: Department of Radiochemistry and Colloids Chemistry, Faculty of Chemistry, Maria Curie-Sklodowska University, M. Curie-Sklodowska Sq. 3, 20-031 Lublin, Poland.
authors.forename: Małgorzata
authors.initials: M
authors.lastname: Wiśniewska
authors.affiliation: Department of Radiochemistry and Colloids Chemistry, Faculty of Chemistry, Maria Curie-Sklodowska University, M. Curie-Sklodowska Sq. 3, 20-031 Lublin, Poland.
authors.forename: Iwona
authors.initials: I
authors.lastname: Ostolska
authors.affiliation: Department of Radiochemistry and Colloids Chemistry, Faculty of Chemistry, Maria Curie-Sklodowska University, M. Curie-Sklodowska Sq. 3, 20-031 Lublin, Poland.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Szewczuk-Karpisz
authors.affiliation: Department of Radiochemistry and Colloids Chemistry, Faculty of Chemistry, Maria Curie-Sklodowska University, M. Curie-Sklodowska Sq. 3, 20-031 Lublin, Poland.
authors.forename: Stanisław
authors.initials: S
authors.lastname: Chibowski
authors.affiliation: Department of Physical Chemistry - Interfacial Phenomena, Faculty of Chemistry, Maria Curie-Sklodowska University, M. Curie-Sklodowska Sq. 3, 20-031 Lublin, Poland.
authors.forename: Konrad
authors.initials: K
authors.lastname: Terpiłowski
authors.affiliation: Institute of Surface Chemistry, National Academy of Sciences in Ukraine, 17 General Naumov Street, Kiev, 03164 Ukraine.
authors.forename: Vladimir Moiseevich
authors.initials: VM
authors.lastname: Gun'ko
authors.affiliation: Institute of Surface Chemistry, National Academy of Sciences in Ukraine, 17 General Naumov Street, Kiev, 03164 Ukraine.
authors.forename: Vladimir Iljich
authors.initials: VI
authors.lastname: Zarko
keywords: Alumina–silica–titania; Mixed fumed oxides; Poly(vinyl alcohol); Polymer adsorption; Potentiometric titration; Suspensions stability; Zeta potential