Adsorption of Hydrolyzed Polyacrylonitrile on Kaolinite: II. Effect of Solution Electrolytes

Mortensen, J. L.

doi:10.2136/sssaj1959.03615995002300030014x

Cited by 21 publications

(14 citation statements)

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“…Further increase in ionic strength from 50 to 200 mol/m 3 had little effect on the PSS adsorption. Similar observations of the influences of pH and ionic strength on the adsorption of charged polymers were reported by Mortensen (1959) and Parfitt (1972).…”

supporting

confidence: 87%

“…According to Sposito (1989), the thickness of the diffuse double layer on montmorillonire decreases from 30 to 3 nm when the ionic strength increases from 0.1 to 10.3 mol/m 3. Ruehrwein and Ward ( 1952) and Mortensen (1959) also suggested that electrolyte was necessary to reduce the electrostatic repulsion between the anionic polymer and the clay particles. Furthermore, studies have shown that solution ionic strength affects the charge and configuration of polymer coil (Markovitz and Kimball, 1950).…”

Section: Influences Of Ph and Ionic Strength On Pss Adsorptionmentioning

confidence: 99%

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The Interaction of Polysaccharides with Silver Hill Illite

Doner

1992

Clays and clay miner.

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Abstract--The clay-polysaccharide interaction is of practical importance in the formation and stabilization of soil aggregates. This study examined the adsorption of three synthetic polysaccharides (PSS) and one soil PSS on Silver Hill illite. The adsorption of PSS was influenced by both the adsorbed cations on the adsorbents and the charge characteristics of the polymers. The adsorbed cations formed different surface complexes with the clay surfaces, with varying ability to screen the surface negative charge and thereby influenced the adsorption of charged polymers. Na-iUite adsorbed substantially higher amounts of the cationic PSS, but lower amounts of the anionic PSS, than hydroxy-A1 illite. The adsorption of the nonionic PSS was, however, little influenced by those adsorbed cations. The adsorption of the soil PSS resembled that of anionic PSS. However, it yielded linear adsorption isotherms due to the heterogeneous nature of the soil PSS. The adsorption of the three synthetic PSS on Na-illite was in the general order: cationic > nonionic > anionic, confirming that electrostatic forces played a role in the adsorption of charged polymers. pH and ionic strength influenced the adsorption of the charged PSS, because of their influences on the charge characteristics of both the polymer and the clay, and on polymer conformation. This study indicates that surface charge properties of both clays and organic polymers and the presence of polyvalent cations in the system are important factors influencing the complexation between soil clays and organic constituents.

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supporting

confidence: 87%

Section: Influences Of Ph and Ionic Strength On Pss Adsorptionmentioning

confidence: 99%

The Interaction of Polysaccharides with Silver Hill Illite

Doner

1992

Clays and clay miner.

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“…Appreciable uptake, however, can take place under acid conditions and/or at high ionic strength when the negative charge on the polyanion becomes effectively neutralized by protonation and/or is screened by the electrolyte. Adsorption is also promoted by the presence of polyvalent cations which act as "bridges" between the anionic groups on the polymer and the negatively charged sites on the clay, as illustrated by the work of Mortensen (1962) (Figure 4). At acid pH, polyanions also adsorb onto the clay crystal edges by electrostatic interactions ("anion exchange") because aluminum exposed at these sites acquires a positive charge.…”

Section: Aspects Of Polymer Adsorptionmentioning

confidence: 99%

Clay-Polymer Interactions: Summary and Perspectives

Theng¹

1982

Clays and clay miner.

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Abstract--The adsorption of uncharged polymers by clays is largely "entropy-driven." Polymer conformation changes from a random coil in solution to an extended form at the surface in which adsorbed polymer segments or trains alternate with loops and tails extending away from the surface. Although the net interaction energy, e, per segment-surface contact is small (--1 kT unit), the total energy of adsorption is large because the fraction of train segments, p, is commonly between 0.3 and 0.5. The adsorption isotherms are typically of the high-affinity type, and there is an apparent lack of desorption on dilution. Positively charged polymers (polycations) are adsorbed largely through electrostatic interactions between the cationic groups of the polymer and the negatively charged sites at the clay surface. Here e >> 1 kT unit and p > 0.7, leading to an almost complete collapse of the polymer chain onto the surface. Indeed, beyond a given level of adsorption charge reversal can occur in that the clay-polycation system effectively behaves as an anion exchanger. Little adsorption occurs with negatively charged polymers (polyanions) due to initial charge repulsion between the polymer and the clay surface. Acid pH, a high ionic strength, and the presence of polyvalent cations in the system enhance and promote polyanion adsorption. Uncharged polymers and polycations can enter the interlayer space of expanding 2:1 type layer silicates but polyanions generally fail to intercalate.The interactions of clays with biopolymers, such as proteins, nucleic acids, and polysaccharides, can be rationalized in similar terms. When intercalation occurs, the interlayer biopolymer is further stabilized against microbial (enzymatic) degradation giving rise to practical applications of clay-polymer complexes as flocculants and soil conditioners. Polyanions are effective as flocculants because of their large "grappling distance," whereas uncharged polymers are better suited as soil conditioners because they can spread over adjacent clay/soil particle surfaces like a coat of paint.

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“…Electrostatic attraction to positive charges at crystal edges, precipitation and coordination involving multivalent exchangeable cations and hydrogen bonding between the carboxyl groups of the polyanion and the oxygens of the clay lattice, have been invoked as bonding mechanisms (Ruehrwein and Ward, 1952;Michaels, 1954;Emerson, 1956Emerson, , 1960Packter, 1957;Warkentin and Miller, 1958;van der Watt and Bodman, 1960). Under the conditions of maximum chain extension and hence optimum flocculating eff• ciency, however, the polyanion is largely repelled by the negatively charged clay surfaces unless the zeta potential is lowered by addition of electrolytes (Ruehrwein and Ward, 1952;Mortensen, 1960). The number of polyanion segments involved in interparticle bonding is therefore not likely to be large.…”

Section: Effect Of Clay-polymer Interactions On Soil~clay Propertiesmentioning

confidence: 99%