Interactions between mica surfaces in sodium polyacrylate solutions containing calcium ions

Journal Article · Mon Nov 01 00:00:00 EST 1993 · Journal of Colloid and Interface Science; (United States)

DOI:https://doi.org/10.1006/jcis.1993.1457· OSTI ID:5846469

Berg, J M; Claesson, P M ^[1]; Neuman, R D ^[2]

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1. Royal Inst. of Tech., Stockholm (Sweden). Dept of Physical Chemistry
2. Auburn Univ., AL (United States). Dept. of Chemical Engineering

Polyacrylic acid (PAA) and its salts find use in a number of different applications, such as in fluids for secondary oil recovery, as dispersing agents for mineral suspensions in, for example, ceramic and paper coating applications, and as flocculants for waste-water treatment. The forces acting between negatively charged muscovite mica surfaces immersed in solutions containing sodium polyacrylate (NaPAA) have been studied. No evidence for PAA adsorption in the absence of calcium ions in the solution was found. However, at a CaCl[sub 2] concentration of about 3 [times] 10[sup [minus]3] M a layer of PAA adsorbed on each surface. At large separations, the forces between the PAA-coated surfaces were dominated by repulsive double-layer forces. At separations below 50--80 [angstrom], depending on the solution conditions, an attractive force in excess of the van der Waals attraction was observed. The adhesion force between the layers was 7-8 mN / m at pH 6 and increased somewhat with increasing pH to about 9 mN/m at pH 10. The authors argue that both the long-range attraction and the adhesion force primarily are due to COO[sup [minus]]-Ca[sup 2+]-[sup [minus]]OOC bridges between the opposing surfaces and possibly charge correlation effects. It was found that calcium ions bind to the PAA and to the mica surface, whereby the electrostatic repulsion between the polyelectrolyte and the surface is lowered. The authors suggest that this is the main reason why calcium ions promote the adsorption of PAA onto negatively charged minerals. However, it also seems likely that calcium ions increase the attractive interactions between the surface and the PAA segments.

• OSTI ID: 5846469
• Journal Information: Journal of Colloid and Interface Science; (United States), Vol. 161:1; ISSN 0021-9797
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
MICA
SORPTIVE PROPERTIES
POLYACRYLATES
ADSORPTION
ADDITIVES
CALCIUM
CATALYTIC EFFECTS
DISPLACEMENT FLUIDS
SURFACE COATING
SURFACE PROPERTIES
VAN DER WAALS FORCES
WATER TREATMENT
ALKALINE EARTH METALS
DEPOSITION
ELEMENTS
ESTERS
FLUIDS
METALS
MINERALS
ORGANIC COMPOUNDS
ORGANIC POLYMERS
POLYMERS
POLYVINYLS
SILICATE MINERALS
SORPTION
400201* - Chemical & Physicochemical Properties