Multivalent anions and

Duzgnues, N., Goldstwin, J. A., Friend, D. S., and Feigner, P. L. Fusion of liposomes containing a novel cationic lipid, V-[2,3-(dioleoyoxy)-propyl]-lV,lV,lV-trimethylam-monium Induction by multivalent anions and asymmetric fusion with acidic phospholipid vesicles. Biochemistry 28 9179—9184, 1989. 

Nanofiltration membranes are negatively charged and reject multivalent anions at a much higher level than monovalent anions, an effect described as Donnan exclusion. Nanofiltration membranes have MgS04 retention and water permeability claims. 

These results have led to the conclusion that ionic mechanisms alone do not entirely explain the complex interactions that occur between basic dyes and acrylic fibres. Hydrophobic interaction also plays an important part and it has been demonstrated [55] that multivalent anions such as sulphate or phosphate can enhance the hydrophobic interaction, thereby also increasing dye sorption in some circumstances. Whilst such results are of interest in terms of dyeing theory, it is extremely doubtful whether there will ever be practical interest in exploiting the use of electrolytes at such high concentrations. 

The hydration of polyoxyethylene (POE) is dramatically affected by the anion present(J 0) in the aqueous phase. The adsorption of HEC (both 2.0 and 4.3 M.S.) was therefore studied in Na SO and Na PO, at equivalent normalities. The multivalent anions are more effective in precipitating POE than is the chloride ion. The amounts adsorbed and the interlayer expansions at normalities below precipitation conditions are given in Table III. The influence of multivalent anions on the intrinsic viscosity of variable M.S. HECs is illustrated in Figure 6. The increased amounts adsorbed are within experimental error, but the decrease in d. with the 4.3 M.S. HEC is notable. The d. changes in the absence of increased adsorption are not explainable in terms of solvation effects. 

Kvaerner Chemetics have developed a novel, patented process [1] for the removal of multivalent anions from concentrated brine solutions. The prime market for this process is the removal of sodium sulphate from chlor-alkali and sodium chlorate brine systems. The sulphate ion in a brine solution can have a detrimental effect on ion-exchange membranes used in the production of chlorine and sodium hydroxide consequently tight limits are imposed on the concentration of sulphate ions in brine. As brine is continuously recycled from the electrolysers back to the saturation area, progressively more and more sulphate ions are dissolved and build up quickly in concentration to exceed the allowable process limits. A number of processes have been designed to remove sulphate ions from brine. Most of these methods are either high in capital or operating cost [2] or have large effluent flows. 

Additional information <1, 7-9, 12-17, 21> (<7> inhibitory effect of phosphonate analogues of 1,3-diphosphoglycerate, overview [49] <21> no effect by glucose 6-phosphate, fructose 6-phosphate, fructose 1,6-phosphate, pyruvate, phosphoenolpyruvate and lactate [70] <13> double-inhibition studies, kinetics, modeling of inhibitor binding, e.g. phosphate [55] <13> enzyme is regulated by multivalent anions, overview [55] <8> no inhibition by Hg [25] <1,7,9,12-17> yeast enzyme is insensitive to thiol reagents [17]) [17, 25, 49, 55, 70]... 

Additional information <13, 21> (<21> no effect by glucose 6-phosphate, fructose 6-phosphate, fructose 1,6-phosphate, pyruvate, phosphoenolpyru-vate and lactate [70] <13> enzyme is regulated by multivalent anions, overview [55]) [55, 70]... 

Whereas the rabbit muscle (68) and brain preparations (129) required 1-10 mM mercaptoethanol and KC1 or LiCl for stability over extended time periods, the preparation described by Lee was not affected by reducing or oxidizing agents (130). Multivalent anions, such as tripolyphosphate, 3-iso-AMP, ATP, and GTP, but not substrate, stabilized the calf brain enzyme against heat inactivation (129, 131). 

Water exhibits all these properties for inorganic and organic salts. A highly polar solvent, water tends to orient around small or multivalent ions and the angle 0 equals 0 and 180° near cations and anions, respectively. Therefore, water molecules bind to ionic molecules known as solvated or hydrated ions. The bound water molecules tend to interchange slowly with bulk water. 

The course of adsorption of oxalate (or citrate) ions at the metal oxide interface is characteristic for multivalent anion adsorption on such interfaces, and is called an envelope adsorption . The adsorption of oxalate ions is complete at low pH range and then decreases to -0% as pH increases. 

The adsorption of multivalent ions is often a very complicated process [19]. In the liquid phase, these ions may exist in the several forms, depending on the presence and a concentrations of other ions. For example with multivalent anions the changes of pH may produce a change in the number of H+ ions connected with them, whereas hydrolyzable cations will change the number of coordinated hydroxyl groups. The presence of other ions may radically change the ionic composition of the solution and thus, also the adsorption properties of the ion. 

The use of buffer solutions is usually advisable for accurate control of the pH of solutions used in spectrophotometric titrations, since the solutions will usually be so dilute (because of the relatively high protein or peptide absorptivity) as to offer little self-buffering. The usual buffers for the pH range from 9 to 13, i.e., borate, glycinate, phosphate, lysine, -aminocaproic acid, etc., are generally transparent through the 2950 A phenolate band. Buffer systems composed of piperidine (pK, 11) and its hydrochloride have been used to avoid the use of multivalent anions in the spectrophotometric titration of ribonuclease (Klee and Richards, 1957), but no other advantage is apparent for this system. 

In the salting-out region it is the anions which are important, although the nature of the cation may have a secondary influence. Salts with multivalent anions, such as sulfates, phosphates, and citrates, are especially effective salts such as sodium and potassium chlorides are relatively ineffective. 

Solution of multivalent anions In the Bronsted sense a multivalent anion A is a multiacidic base, which can add protons stepwise. If the protons originate from water, and for an ion A, we have two stages of hydrolysis ... 

---