Adsorption of Poly(Vinyl Alcohol) on Montmorillonite

Abstract

The adsorption of poly(vinyl alcohol) (PVA) on montmorillonites saturated with calcium (Ca-Mt) and sodium (Na-Mt) as a function of the pH value and PVA concentration in aqueous solution was studied. Owing to the binding effect of the bivalent cation, the adsorption of PVA on Ca-Mt decreases as the pH of the suspension increases, whereas adsorption on Na-Mt is unaffected by the suspension pH. The adsorption maximum of PVA (pH 6) on Ca-Mt was 151.2 mg of PVA g−1 of clay, which is considerably lower than that on Na-Mt (496.2 mg g−1). These adsorption data coincide with the basal spacings obtained for the clays: 1.72 and 2.26 nm for Ca-Mt and Na-Mt, respectively. Sodium permits a greater separation between the clay laminae than calcium, but in both clays the presence of the polymer gives rise to a material in which PVA is intercalated between the laminae and is also adsorbed on the external surface. Adsorption is a slow process and is irreversible in both clays.

Synergistic and Competitive Aspects of the Adsorption of Poly(ethylene glycol) and Poly(vinyl alcohol) onto Na-Bentonite

“…The higher molecular weight (MW 25,000) is likely to contribute to the higher coverage compared to that of Bussetti and Ferreiro. 25 Bajpai and Vishwakarma 14 observed an upturn, similar to that presented here, in the amount of PVOH (MW = 37,500) adsorbed onto…”

Poly(vinyl alcohol)/Clay‐Based Nanocomposite Hydrogels: Swelling Behavior and Characterization

“…On the other hand, several authors have studied PVA nanocomposites. [20][21][22] However, the focus of these studies was based mainly on the intercalation process between PVA and sodium montmorillonite, and the swelling capacity of these materials was not taken into account.…”

Apparent and partial specific adsorption of 1,10-phenanthroline on mixtures of Ca-montmorillonite, activated carbon, and silica gel

“…Three substances were used for the preparation of the mixtures used as adsorbents of 1,10-phenanthroline: (1) montmorillonite from Cerro Bandera, Argentina [12]: the fraction <2 µm was saturated with Ca by successive washing with CaCl 2 0.5 M, and a clay was obtained with 0.75 mEq/g of exchangeable calcium (designated as Ca-Mt) and a given specific surface area of 614.2 m 2 /g determined by adsorption of orthophenanthroline at pH 6 [13]; (2) activated coal (AC) of Merck (Germany) as an amorphous powder that passes through a 200-µm sieve, with specific surface of 899.2 m 2 /g determined by OP adsorption [14];…”

“…Orthophenanthroline (OP): 1,10-Phenanthroline monohydrochloride monohydrate (C 12 H 9 N 2 Cl·H 2 O) of analytical grade, provided by Merck, Germany, having a molecular weight of 234.69 g, a melting point of 224-228 • C, 2 mol/l solubility in water giving a solution of pH 3, and a crosssectional area of one molecule of 0.60 nm 2 [9,10,15]. The pK values corresponding to the reactions of the dissociation of the protons are pK 1 = −1.4 and pK 2 = 4.85.…”