Cationic polymer suspensions

JL Zatz, L Schnitzer, P Sarpotdar. Flocculation of sulfamerazine suspensions by a cationic polymer. J Pharm Sci 68(12) 1491-1494, 1979. 

Some preliminary experiments have been conducted using the new technique, with kaolin suspensions and cationic polymers. 

It is worth noting that the specific resistances obtained by flocculation with cationic polymers are much less than those achieved by simple salts. For instance, when the kaolin suspension is completely destabilized by the addition of a calcium salt, the specific resistance is only reduced by a factor of about two. A ten-fold reduction can easily be achieved by cationic polymers. 

The method described here provides a convenient means of determining the specific filtration resistance of fairly dilute suspensions. Results for clay suspensions flocculated by cationic polymers show that the specific resistance gives a sensitive indication of flocculation and is a useful guide in the selection of optimum flocculant concentrations. In a series of trials not reported here, it has been shown that the specific resistance results are very well matched by re-filtration rate data, as expected. The results also agree well with other, unrelated techniques. For more concentrated suspensions, some discrepancies have been found between permeability methods and other measures of flocculation (4). 

Flocculation of alumina suspensions obtained by the sequential addition of polystyrene sulfonate (M j, = 4600) and cationic polyacrylamide (M, = 4,000,000) at pH 4.5 is compared in Figure 7.33 with that obtained using single polymers. While the anionic polystyrene sulfonate had only a minor effect, cationic polyacrylamide did not produce any flocculation. However, when used together, both polymers adsorb completely. This coadsorption is attributed to the interaction of complexes between cationic polyacrylamide and the polystyrene sulfonate at the solid-liquid interface. The mechanism of the superior flocculation obtained with the dual polymer system is illustrated schematically in Figure 7.34. The anionic polystyrene sulfonate adsorbs on alumina surface and acts as an anionic anchor for the adsorption of the long-chain cationic polymer, which ultimately provides interparticle bridging and excellent flocculation. 

In the literature, two methods are often used to prepare cationic polymer-DNA complexes. The first method is direct mixing, which is generally used to formulate traditional polyplexes. According to this method, aqueous suspensions of cationic polymers and plasmid DNA are mixed rapidly. " The other method is the detergent dialysis method, which was initially used for preparing relatively stable cationic lipid-DNA particles. For this method, a DNA and cationic lipid mixture is dissolved in a detergent solution, which is followed by a subsequent dialysis process to remove the detergent. 

In a control experiment, the anionic dep-poly7 (M = 22,000 g/mol) was tested against the liposome suspensions and no lysis was observed at comparable concentrations. It is remarkable that dep-poly7, which has the same hydrophobicity as the cationic dep-poly8, caused no lysis. A change from cationic to anionic character of the polymer resulted in a dramatic decrease of membrane disruption activity. Three commercially available cationic polymers, polyallylamine (M = 25,000 g/mol), polyethyleneimine (M = 400,000 mol), and poly(dimethyldiallyl ammonium dichloride) (M = 75,000 g/mol), were also tested as control experiments. These polymer samples provide models for primary amine, secondary and tertiary amine (hyperbranched PEI), and... 

Usually, cationic polymers of high molar mass are used for flocculating the animucafly charged suspension. However, the improved effect of dual systems is also appreciated. The applicatimi of two or even more components, added in sequence... 

In pipes at higher Reynolds numbers, ranging from 2000 to 25 000, and therefore in turbulent flow, Doll has demonstrated the mixing and flocculation conditions in laboratory systems. These employed silica particle suspensions, flocculated with three different cationic polymers, and the turbulent root mean square velocity gradient (G) characterized the influence of flow rate on reaction rate. In West Berlin, a practical pipe flocculator has been used prior to the entry of treated waste water into a sedimentation tank, based on the concepts set out in section 4.10.3, with the pipe set out in a snake-like pattern on the ground surface. 

The amounts of alkyl sulfosuccinate and of the cationic polymer adsorbed on the fillers and fibers were determined by the depletion method. 1 g of the filler or 0.5 g of the fibers were shaken with 100 ml of surfactant or polymer solution of known initial concentration at pH 8.5 in a glass tube for 60 min. The suspension was subsequently separated by centrifugation (labcentrifuge UJIIE Heraeus-Christ, FRG) at 4000 rpm for 60 min. Control experiments without the addition of solids did not indicate any change in the polymer concentration during centrifugation. 

Cationic polymers directly adsorb ionically onto the negatively charged suspended particles in organic waste and soil waste and cause aggregation [3]. Cationic polymers can adsorb tightly to particles in suspension. As the... 

Nanoparticles of Pd were prepared in kaolinite suspension containing surfactant and neutral or cationic polymer in methanol medium. Disaggregation of the kaolinite lamellae was brought about by the intercalation of DMSO at r = 65°C. The DMSO was removed from between the lamellae by repeated washes with methanol and decanting for 5 days. The MeOH-kaolin-... 

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