Polyacrylic acid adsorption

J.-L. Liao, C-M. Zeng, S. Hjeiten and J. Pawliszyn, Solid phase micro exti action of biopolymers, exemplified with adsorption of basic proteins onto a fiber coated with polyacrylic acid , ]. Microcolumn Sep. 8 1-4. (1996)... 

The proposed mechanism of effect of surfactant and ultrasound is reported in Fig. 7.5. The long chain surfactant molecules attach to surface of nanoparticles due to physical adsorption. Only thin layer is adsorbed onto the CaC03 nanoparticles. Due to presence of ultrasound and use of surfactant will control the nucleation. Surfactant keeps the particles away from each other by preventing flocculation due to change in surface tension of reaction mass. The concentration of additives was changed from 0.2 to 1.0 g/L. Addition of 0.2 g/L tripolyphosphate shows the increase in the rate of precipitation which is determined from the Ca(OH)2 consumption. Polyacrylic acid shows the least rate of precipitation (0.115 mol/1), which... 

Flocculation is indeed dependent on polymer adsorption, and there are hypotheses correlating the two phenomena, but often these have been put forth without detailed measurement of the two phenomena simultaneously (10-13). In this paper, flocculation is investigated as a function of polymer and solution properties and hydrodynamic conditions by measuring different properties of the system, including adsorption, using well characterized kaolinite and polymer samples prepared specifically for this purpose. Also, the role of concentration and charge density of polyacrylamide and polyacrylamide-polyacrylic acid co-polymers in determining kaolinite flocculation is examined under controlled hydrodynamic conditions. 

The presence of pre-adsorbed polyacrylic acid significantly reduces the adsorption of sodium dodecylsulfonate on hematite from dilute acidic solutions. Nonionic polyacrylamide was found to have a much lesser effect on the adsorption of sulfonate. The isotherm for sulfonate adsorption in absence of polymer on positively charged hematite exhibits the typical three regions characteristic of physical adsorption in aqueous surfactant systems. Adsorption behavior of the sulfonate and polymer is related to electrokinetic potentials in this system. Contact angle measurements on a hematite disk in sulfonate solutions revealed that pre-adsorption of polymer resulted in reduced surface hydrophobicity. 

Figure 3. Equilibriimi adsorption densities of sodium dodecylsul-fonate on hematite at pH 4.1 and 0.001 M NaCl in the presence and absence of pre-adsorbed polyacrylic acid.

Figure 4. Equilibrium adsorption densities of polyacrylic acid on hematite at various pH values. Reproduced with permission from Ref. 22. Copyright 1983, Colloids and Surfaces.

Fig. 43 Schematic representation of the adsorption process of pyrene labeled polyacrylic acid on alumina at different pH...

Figure 11.15 Cation-exchange micro-LC analysis of a mixture of model proteins (a) the original sample consisting of myoglobin (M), cytochrome C (C) and lysozyme (L) (b) and (c) proteins adsorbed on to and then released from the polyacrylic acid coated fibre with extraction times of 5 and 240 s, respectively. Reprinted from Journal of Microcolumn Separations, 8, J.-L. Liao et al., Solid phase micro extraction of biopolymers, exemplified with adsorption of basic proteins onto a fiber coated with polyacryfic acid, pp. 1-4, 1996, with permission from John Wiley Sons, New York.

Santhiya, D. et al., Effect of polymer molecular weight on the adsorption of polyacrylic acid at the alumina-water interface, Colloids Sutf. A, 133. 157. 1998. 

FIG. 7 Adsorption/desorption hysteresis of hydrophobically modified polyacrylic acid (HM-PAA, , ) on polystyrene, compared to that for unmodified PAA ( , O). Concentration polymer 10 mg I. electrolyte 0.001 M NaCl. Closed symbols adsorption as a function of pH open symbols adsorbed amounts after initial adsorption at pH 3 and subsequently increasing the pH. (Data from Ref. 27.)... 

FIG. 9 Change in molecular weight distribution of polyacrylic acid in solution with time during adsorption onto BaTi03 (no electrolyte added). C0 chromatogram before adsorption chromatograms after adsorption for the indicated time in hours (h) or days (d). (Adapted from Ref. 28.)... 

Gobel JG, Besseling NAM, Cohen Stuart MA, Poncet C. Adsorption of hydrophobically modified polyacrylic acid on a hydrophobic surface hysteresis... 

De Laat AWM, Van den Heuvel GLT, Bohmer MR. Kinetic aspects in the adsorption of polyacrylic acid salts onto BaTi03. Colloids Surfaces A 1995 98 61-71. 

Gebhardt JE, Fuerstenau DW. Adsorption of polyacrylic acid at oxide-water interfaces. Colloids Surf 1983 7 221—231. 

Foissy A, El Attar A, Lamarche JM. Adsorption of polyacrylic acid on titanium dioxide. J Colloid Interface Sci 1983 96 275-287. 

Aggregation and fragmentation of colloidal particles has been investigated further employing natural polyelectrolytes like humic substances. Adsorption of humic acids on aluminum oxide was determined to resemble interfacial deposition on the basis of methods previously employed for the aluminum oxide/polyacrylic acid system [88]. Complexation by soluble aluminum ions produces pH drops that are very similar to that determined for polyacrylic acid, and essentially humic acids were determined to exert effects on the stability of colloidal aluminum oxide particles at pH 5 that are very similar to polyacrylic acid. 

Fig. 4.21. Schematic representation of the adsorption process of pyrene-labeled polyacrylic acid on alumina. (A) At low pH, polymer is coiled in solution which leads to (B) adsorption in coiled form. (C) Subsequent raising of the pH causes some expansion of the polymer. (D) Polymer at high pH in solution is extended and binds (E) strongly to the surface in this conformation. (F) Subsequent lowering of pH does not allow for sufficient intrastrand interactions for coiling to occur.

Markovic, B., Somasundaran, R, Adsorption of Polyacrylic acid on porous and non-porous alumina, 205 ACS National Meeting, Denver, CO, Abstract, 1993, p. 83. 

D.N. Misra, Adsorption of polyacrylic acids and their sodium salts on hydroxyapatite effect of relative molar mass, J. Colloid Interface Sci. 181 (1996) 289-296. 

In-situ ATR FTIR spectroscopy was used to study the interaction between the differently charged model proteins human serum albumin, lysozyme, immunoglobulin G and multilayer assemblies, which were deposited by alternating adsorption of polyethyleneimine and polyacrylic acid onto silicon crystals. Low adsorbed protein amounts were observed if the top polyelectrolyte layer and the protein were equally charged, whereas enhanced protein adsorption occurred for electrostatic attraction between protein and top polyelectrolyte layer. 18 refs. 

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