Polyelectrolyte strong

The largest area of polyelectrolytes application is potable and waste water treatment by filtration [108]. Here the anionic, nonionic, and cationic poly electrolytes are used. The USA, France, Germany, Japan, and other countries are widely use polyelectrolytes in direct water and wastewater filtration. Large quantities of ultra-high quality water are produced by suitably designed direct filtration equipment employing polyelectrolytes [109]. Polyelectrolytes strongly improve removal of color, oil, asbestos at treatment of water by filtration [110]. 

NaUet F, Jannink G, Hayter J, Oberthur R, Picot C. Observation of the dynamics a polyelectrolyte strong solutions by quasielastic neutron scattering. J Phys 1983 44 87-99. 

Since the electrostatic potential sharply decreases with increasing distance from the polyelectrolyte cylinder, the degree of reactivity modification by functional groups fixed to the polyion is strongly dependent on the distance from the cylinder surface. Considerable electrostatic potential effects on the photoinduced forward and thermal back electron transfer reactions, which will be discussed in the following chapters, can be attributed to the functional chromophore groups directly attached to the polyelectrolyte back-bone through covalent bonds. 

The salt effect is very strong in polyconjugated polyelectrolytes. Figure 15 is a graph of the proton dissociation energy vs. the dissociation degree of PPA of different structures. Also, the graphs for poly(methacrylic acid) and a copolymer... 

Furthermore, Cordes etal995 observed the saturation-type kinetics, strongly suggesting the formation of a complex between the polyelectrolyte and ester preceding bond cleavage reactions, as has been found for micellar catalysis11,1015. 

FIG. 13 Schematic drawing of possible binding modes of counterions to polyelectrolyte chains. Counterions loosely bind and form a cloud around the polyelectrolyte chains when the interchain distance (d) is greater than 2.4 0.5 nm, while they strongly bind to form nearly neutral polyelectrolytes at smaller distances d < 2.4 0.5 nm). 

The precipitation of polyelectrolytes by the addition of multivalent counterions may be explained in these terms. When there are no multivalent ions in solution there is a strong repulsive force between polyions and the osmotic pressure is large. The solubility of polyions is a result of these repulsive forces. 

In solutions, the counterions of poly electrolytes are HjO (for the polyacids) and OH (for the polybases), cations such as K+ and Na, or anions such as Cl (for the polysalts). The addition of polyvalent counterions (such as Ca, Mg, Cu, AT ) produces ionic cross-linking interfering with solubility The polyelectrolyte precipitates and may be redissolved upon addition of a strong acid (such as HCl). This can be regarded as a special case of ion exchange. 

All biological systems contain aqueous electrolyte solutions. These solutions consist of strong electrolytes (inorganic salts) as well as various organic substances with acidic or basic functional groups which usually behave as weak electrolytes. The solutions are often gel-like in their consistency because of the polyelectrolytes, proteins, and other macromolecules contained in them. The pH values of biological solutions as a rule are between 6.7 and 7.6. 

A strongly anionic, polyelectrolyte can be made from lignin by conducting a graft polymerization in the presence of 2-propenamide and 2,2-dimethyl-3-imino-4-oxohex-5- ene-1-sulfonic acid or its salts. 

The adsorption of HPAM on sand (Figure 4) is not detected below a threshold value of Ca2+ due to strong electrostatic repulsion between the polyelectrolyte and the highly charged negative surface. This threshold value, which was also observed in the case of monovalent ions (9), represents the point where the critical adsorption energy is overcome, and once this value is surpassed, adsorption increases sharply. This form of adsorption behavior is in line with predictions of theories on polyelectrolyte adsorption (20). 

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