Anionic Acrylamide Copolymers Research Articles

Adsorption and flocculation properties of a binary system based on (co)polymers of acrylamide and low- molecular weight amine-containing surfactants in a saline medium

The process of flocculation of a calcium-magnesium solid phase formed in an aqueous-salt solution with the introduction of calcium-containing precipitants using polyacrylamide, cationic and anionic acrylamide copolymers was studied. With the introduction of polymers, an increase in the dispersion settling rate was observed in the concentration range of 0.5–3.0 mg/g, to a greater extent for the anionic copolymer. In the presence of an amine-containing surfactant, the sedimentation rate increased with the introduction of polymers by a factor of 1.1–1.3 compared to dispersions without surfactants. Using an anionic copolymer as an example, it was shown that the adsorption of amine and the sedimentation rate of dispersion increase with the increase of the polymer molecular weight. It was found that the concentration of the anionic copolymer and the pH of the medium also influence the adsorption of amine. Based on the obtained data, an effective method of water-salt solutions purification from amine-containing surfactants and magnesium salts (purification degree 99.5–99.8 %) that can be used at mining and processing enterprises was developed.

Hydrodynamic and adsorption properties of anionic acrylamide copolymers in water-salt media

Rheological properties and concentration cross-overs of anionic acrylamide copolymers in saline solutions (potassium chloride) were investigated by using capillary viscometer method. Area of non-overlapping coils between the crossover concentration and the concentration of fluctuation mesh formation was determined; it was shown that with increase of salt concentration this area practically disappears, i.e. mass transfer mechanism changes near the crossover concentration. It was shown that at low concentrations of potassium chloride increasing the content of ionic groups of macromolecules leads to reduction in the crossover concentration and increase in the effective volume. It is found that the kaolin adsorption capacity decreases when polymers are adsorbed from saline solution, and the adsorption constant is significantly higher in the presence of salt than in water.

Flocculating and Hydrodynamic Properties of Aqueous-Salt Solutions of Acrylamide Polymers

Specific features of flocculation of aqueous-salt (KCl, NaCl) clay dispersions with polyacrylamide and anionic acrylamide copolymers, including the influence exerted by the procedure of polymer dissolution in water or salt solution on the sedimentation rate and density of floccules and on the hydrodynamic properties of the polymers, are described. The use of aqueous-salt solutions of flocculants enhances the flocculating effect. The most effective flocculant for aqueous-salt clay dispersions is polyacrylamide prepared in a salt solution, which is due to higher flexibility of the polymer chain. The results obtained are of practical interest in connection with the possibility of enhancing the efficiency of the flocculation of aqueous-salt clay dispersions in dressing of potassium ores.

Anionic copolymers of acrylamide and polyacrylic acid as hydroaccumulating polymeric materials

A method for hydrogels production by the formation of cross-linked binary polymer complexes is proposed. Necessary conditions for synthesis were determined, providing a high degree of swelling of hydroaccumulating polymeric materials based on anionic copolymers of acrylamide and polyacrylic acid. Chemical interaction of components of polymer complex has been proved by the methods of infrared spectroscopy and potentiometric titration. The possibility of moisture absorption control of hydrogels depending on synthesis conditions and application purpose was shown.

Complexation of anionic copolymers of acrylamide and N-(2-hydroxypropyl)methacrylamide with aminoglycoside antibiotics

The complexation of aminoglycoside antibiotics neomycin, gentamicin, kanamycin, and amikacin in the form of free bases with carboxyl- and sulfo-containing copolymers of acrylamide and N-(2-hydroxypropyl)methacrylamide (HPMA) in water and water-salt solutions is studied by means of viscometry, equilibrium dialysis, potentiometric titration, and molecular hydrodynamics. Factors influencing the stability of formed copolymer-antibiotic complexes and determinations of their toxicity are established.

PERFORMANCE EVALUATION OF ANIONIC POLYMER-CATIONIC SURFACTANT COMPLEX COAGULANTS IN WATER TREATMENT

The performance of some complex coagulants derived from weak and medium anionic polymers and medium cationic surfactant in coagulation-flocculation process for water treatment was experimentally investigated by carrying out kinetic studies and by determining the optimum coagulant dose. The complex coagulants were prepared from weak anionic and medium anionic copolymers of acrylamide and sodium acrylate with the commercial names Praestol 2515 and Praestol 2540, and medium cationic surfactant derived from triethanolamine with the commercial name Tetranyl AT-7590. The coagulation-flocculation process was studied for suspensions of kaolin particles in tap water. The electro-kinetic studies revealed that the addition of surfactant leads to a significant decrease of coagulant concentration for which the electro-kinetic potential of the dispersion medium becomes zero. The favorable influence of the addition of surfactant also resulted from the kinetic studies. Thus, the formation of some large flocks leads to shortening the flocculation period. These results are consistent with those obtained for sedimentation velocity, sludge volume and separation efficiency.

Retention aid polymer interactions with cellulosic surfaces and suspensions: A review

Retention aids can be defined as very-high-mass, water-soluble polymers that are added to cellulosic fiber slurries before the formation of paper in order to improve the efficiency with which fine particles, including cellulosic fines, are retained in the paper product. Optimization of retention aid performance can be a key to achieving efficient and environmentally responsible papermaking objectives. This article reviews various published theories related to retention aid use. Findings related to three main classes of retention aid polymers are considered: cationic acrylamide copolymers (cPAM), anionic acrylamide copolymers (aPAM), and polyethylene oxide (PEO). While many aspects of the interactions of each of these classes of retention aid products can be understood based on colloid chemistry principles, further research is needed in order to more fully bridge the gap between theory and practice.

Effect of concentration and composition of anionic copolymers of acrylamide on flocculation characteristics of titanium dioxide suspension (Anatase)

The kinetics of restricted sedimentation of model disperse system, titanium dioxide suspension of anatase modification, at dosed addition of high-molecular anionic acrylamide copolymers with various concentrations of ionogenic chains into a water-salt system (0.06 N NaCl) was studied. The effect of concentration and composition of the acrylamide copolymers on their integral and differential flocculation activities was analyzed.

Synthesis and aqueous solution properties of hydrophobically modified anionic acrylamide copolymers

AbstractIn this investigation, hydrophobically modified polyacrylamide with low amounts of anionic long‐chain alkyl was synthesized by the free radical polymerization in deionized water. This water‐soluble copolymerization method is more convenient compared with the traditional micellar copolymerization methods. The copolymers were characterized using Fourier transform infrared, 1H NMR, and the molecular weight and polydispersity were determined using gel permeation chromatography. The solution behavior of the copolymers was studied as a function of composition, pH, and added electrolytes. As NaCl was added to solutions of AM/C11AM copolymers or pH was lowered, the shielding or elimination of electrostatic repulsions between carboxylate groups of the C11AM unit lead to coil shrinkage. The steady shear viscosity and dynamic shear viscoelastic properties in semidilute, salt‐free aqueous solutions were conducted to examine the concentration effects on copolymers. In addition, the shear superimposed oscillation technique was used to probe the structural changes of the network under various stresses or shear conditions. We prepared hydrophobically modified polyacrylamide with N‐alkyl groups in the aqueous medium. The advantage of this method is that the production is pure without surfactants. These results suggest that the unique aqueous solution behavior of the copolymers is different from conventional hydrophobically associating acrylamide. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 2465–2474, 2008

Effect of water-soluble polymeric additives on energy expenditure in transportation of water-oil systems in turbulent mode

New installation of the circulation type was used to perform a joint analysis of rheological and energy parameters of turbulent flows of water and water-oil media in the presence of polymeric additives of anionic copolymers of acrylamide. Copolymers with varied molecular mass were produced by ultrasonic destruction of a starting high-molecular-weight sample of the polymer under mild conditions. The effect of the molecular mass of the polymer additive on the specific energy expenditure in the case of circulation of water-oil media in the turbulent mode was analyzed.

Successive adsorption of polyacrylamide compounds from electrolyte solutions on the surface of kaolinitic clay particles

Successive adsorption of oppositely charged polyelectrolytes, namely, cationic and anionic acrylamide copolymers, on a solid phase surface from solutions with high ionic strength is investigated. The constants of the Freundlich equation are calculated for the adsorption of different polymers. The interrelation between the adsorption values of polymers and their flocculation activity with respect to clay-salt suspensions is determined. The successive adsorption of oppositely charged polyelectrolytes strongly affects the flocculation due to the formation of polyelectrolyte complexes on the surface of clay particles. The mechanism for complexation is proposed.

Peculiarities of the formation of polyacrylamide compound-based polyelectrolyte complexes in the course of the flocculation of clay-salt dispersions

Peculiarities of the formation of polyelectrolyte complexes based on cationic and anionic copolymers of acrylamide having different macromolecule charge densities on the surfaces of kaolin particles in highly concentrated salt solution are investigated. The interactions of the copolymers with the clay particle surface and with each other are studied by electrokinetic and IR spectroscopy methods. The rheological properties of kaolin suspensions are investigated in a salt solution in the presence of the polyelectrolytes. The flocculation ability of the polyelectrolytes and their binary mixtures with respect to clay-salt dispersion is estimated. The mechanism for the formation of polyelectrolyte complexes on the surface of clay particles is discussed. It is shown that the complexation of oppositely charged polyelectrolytes on the surfaces of clay particles intensifies the flocculation of clay-salt dispersions.

Influence of the molecular parameters of anionic acrylamide copolymers on the value of the Thoms effect in direct oil emulsions

The influence of molecular parameters (molecular weight and polydispersity in molecular weight) on the value of the reduced Thoms effect in 10% direct oil emulsions has been analyzed with the example of the specimens of anionic acrylamide copolymer of different molecular weight, which were obtained by the ultrasonic-destruction method. The prospects of anionic acrylamide copolymers for use as admixtures reducing the drag of turbulent oil-emulsion flows have been noted for the complex heterophase system studied.

Flocculation activity of anionic copolymers of acrylamide with respect to titanium dioxide suspension as influenced by their molecular properties

The kinetics of sedimentation of titanium dioxide suspension in the presence of ionic (anionic) acrylamide copolymers in the mode of free (unrestricted) sedimentation was studied. The effect of concentration and molecular properties of the copolymers on their flocculation activity was evaluated by sedimentation analysis.

Toms Effect in Direct Crude Oil Emulsions as Influenced by the Stream Velocity and Concentration of Anionic Copolymers of Acrylamide

The major relationships in the Toms effect in direct crude oil emulsions differing in the dispersed phase concentration were studied on a modified turbulent rheometer with anionic copolymer of acrylamide as the polymer additive. The Toms effect was studied as influenced by the polymeric additive concentration and shear stress.

Flocculation Activity (with Respect to Ocher) of Anionic Copolymers of Acrylamide in the Mode of Restricted Sedimentation as Influenced by Their Chemical Heterogeneity

The kinetics of sedimentation of an aqueous ocher suspension in the presence of ionic (anionic) acrylamide copolymers in the mode of restricted sedimentation was studied; the effect of composition and of the composition polydispersity of the copolymer on the flocculation activity with respect to ocher was evaluated.

Adsorption of bilayers and multilayers of cationic and anionic co-polymers of acrylamide on silicon oxide

Silica surfaces were consecutively treated with copolymers of cationic and anionic polyacrylamides (C-PAM and A-PAM, respectively) and the layer-by-layer build-up was continuously monitored with the aid of stagnation point adsorption reflectometry (SPAR). Four different charge densities of the cationic polymer and one charge density of the anionic polymer were studied. The solid substrate used in the investigation was an oxidized Si wafer, the charge of which was varied by performing the measurements at different pH. Adsorption measurements were performed both in deionized water and with a background electrolyte concentration of 0.01 M NaCl. The results show that the adsorption of C-PAM at pH 6 was dominated by electrostatic interactions. However, a significant nonionic contribution to the adsorption of C-PAM on SiO 2 was detected-when the results of adsorption measurements conducted in deionized water and in 0.01 M NaCl were compared. At pH 9, the adsorption of C-PAM onto SiO 2 was found to be geometrically restricted since the adsorption stoichiometry between the polymer charges and the charges on the surface was less than 1 irrespective of the charge of the C-PAM. Adsorption of the A-PAM onto the C-PAM covered surface increases as a function of the adsorbed charges in the first layer. Experiments showed that it was possible to form multilayers of polyelectrolytes on the SiO 2 surface provided the charge of the C-PAM was high enough. The critical charge of the polyelectrolyte for the formation of multilayers was also dependent on the charge of the substrate; that is, the lower the surface charge the higher the critical charge of the C-PAM. The substrate affected the amount of polyelectrolyte adsorbed up to the fifth layer. For further layers there was almost a stoichiometric relationship between the charges of the polyelectrolytes in consecutive layers. Results from studies of the formed multilayers with a quartz crystal microbalance (QCM-D) indicated that there was a close correlation between energy dissipation into the multilayers and a decrease in the adsorption as detected with SPAR. This in turn indicates that a decrease in the reflectometer signal does not necessarily indicate a decrease in adsorption.

Structural Effect and Composition of Anionic Copolymer on Protein Flocculation

Flocculation of lysozyme with anionic copolymers of acrylamide, acrylic acid, and sodium styrene sulfonate used as flocculants was performed in pursuit of high flocculation efficiency. Two major factors, pH and ionic strength, are used to investigate the relationship of the flocculation behavior of protein by copolymers and the functional group (–COOH, –NH2, –SO3H) compositions of these copolymers. The protein flocculation can be controlled by adjusting pH. In addition, the various copolymers exhibit differing effects on ionic strength induced protein flocculation. FT-Raman spectroscopy was applied to investigate the mechanism of interaction between protein and copolymer. An attempt was made to understand how the pH and ionic strength change the surface chemical characteristics of protein and copolymers, as well as the relationship between the structure of copolymer and the protein flocculation process.

Optimization of the polyelectrolyte dosage for dewatering sewage sludge suspensions by means of a new centrifugation analyser with an optoelectronic sensor

The flocculation of sewage sludge with poly(diallyldimethylammonium chloride) (PDADMAC) as well as cationic, poly[acrylamide-co-(N,N,N-trimethylammoniumethylacrylate chloride)] (PTAC), and anionic acrylamide copolymers, poly(acrylamide-co-acrylate) (PAAM/AA), was investigated by using a new method to evaluate the velocity of centrifugal separation and the packing behaviour of the sediments. By means of a centrifugation analyser with an optoelectronic measuring system the position of the centrate/sediment interface of the conditioned suspensions can be determined as a function of the separation time, which allows the polyelectrolyte dosage to be optimized for various rotational speeds. At high centrifugal accelerations it was found that using the anionic polyelectrolyte PAAM/AA does not result in better dewatering performance, whereas both polycations recorded high degrees of separation. Furthermore, the measurements with the high-molar-mass PTAC indicate a high resistance to centrifugation which correlates with floc stability. In contrast, addition of the low-molar-mass PDADMAC gives more fragile flocs, leading to faster collapse of the sludge cake in the compression zone of the centrifuge at lower gravitational forces. These experimental findings agree well with the much higher filtration capacity of sludges conditioned with PTAC which was measured by means of a pressure filtration device. Comparisons of the optimum polyelectrolyte concentrations obtained by pressure filtration or centrifugation at low gravitational forces with the zeta potential of the flocculated particles appear to be consistent with bridge formation for PTAC and with the charge patch mechanism for PDADMAC. The centrifugation experiments at high centrifugal accelerations show an optimum separation efficiency at relatively low degrees of coverage and a high level of agreement with the large-scale process.