Sulfate stability

The low TTA dependence at 35.0°C probably is attributable to dissolution of TTA in the aqueous phase. Observation of fourth-power dependence on acidity argues against any change in the extraction mechanism (e.g., Pu(IV) reduction or NO3 involvement). An aqueous Pu(TTA)3+ complex has been reported (14, 15) and this possibility has been considered in the error analysis of the Pu(IV)-sulfate stability constants. 

FIG. 2 -potential as a function of layer number for PDADMAC/PSS multilayers on sulfate-stabilized polystyrene (PS) latices. The multilayers were assembled onto the negatively charged PS latices ( -potential of ca. -65 mV, layer number = 0) by the consecutive deposition of PDADMAC (odd layers) and PSS (even layers). Positive values are observed for PDADMAC deposition, and negative values for PSS adsorption. The alternating values are characteristic of stepwise growth of multilayer films on colloids. 

The colorimetric method of Jakovljevic which was first used to assay vinblastine sulfate may also be employed to assay vincristine sulfate. The method is summarized in the Vinblastine Sulfate profile in this publication. The absorptivity of vincristine sulfate at the maximum absorption peak is only 75% of that exhibited by vinblastine sulfate at the same peak9. The method is known to be useful in measuring the stability of vinblastine sulfate and may possibly be useful in the measurement of vincristine sulfate stability... 

Soma, 1. and Papadopoulos, K.D., Ostwald ripening in sodium dodecyl sulfate-stabilized decane-in-water emulsions, J. Colloid Interface ScL, 181, 225, 1996. 

Solvent quality. Various solutes added in high concentrations affect solvent quality and thereby solubility and conformation of macromolecules see Sections 3.2 and 6.2.1. Solutes may thus affect conformational stability. Relations are not straightforward for proteins, because they have polar as well as apolar groups, that may be affected in opposite manner. For salts (ions), the Hofmeister series (Section 3.2) is mostly obeyed. Examples are in Figure 7.8a. It is seen that the very hydrophilic ions at the beginning of the series, i.e., ammonium and sulfate, stabilize the conformation, whereas those at the other end, guanidinium and thiocya-... 

Sodium diisopropyl naphthalene sulfonate Sodium 2-ethylhexyl sulfate Sodium polyacrylate Xanthan gum stabilizer, paints/coatings Cl 3-15 pareth-20 Sodium octyl sulfate stabilizer, paints latex emulsion Ammonium zirconyl carbonate stabilizer, paper... 

The chemistry of rare earths is often discussed only in terms of the trivalent ions and indeed, contrary to the actinides, the oxidation states encountered in lanthanide compounds in the solid state and especially in solution are few in number. Standard electrode potentials M(II-III) and M(III-IV) indicate that, besides the trivalent rare earth ions, only Eu (-0.35 V), Yb + ( — 1.15 V), Sm + ( — 1.55 V) and Ce (+1.74 V) are sufficiently stable to exist in aqueous solutions (Nugent, 1975). It has long been known that alkaline conditions and many complexing anions such as nitrate, phosphate and sulfate stabilize Ce(IV) (Jorgensen, 1979) and recently it has been shown that large complex-forming ligands such as heteropolyanions also stabilize to some extent tetravalent praseodymium and terbium (Spitsyn, 1977). 

T. R. Ingraham, Sulfate stability and thermodynamic phase diagrams with particular reference to roasting, Applications of Fundamental Thermodynamics to Metallurgical Processes, p. 187. Gordon and Breach, New York, 1967. 

While lanthanide phosphate and carbonate stability constants increase substantially between La and Lu, the complexation behavior of lanthanides with sulfate changes very little across the lanthanide series. This difference in complexation constant trends is consistent with inner sphere (COj ) versus outer sphere (SO ) complexation behavior (Byrne and Li 1995). Stability constants for lanthanide sulfate complexes at 25 C and zero ionic strength could be well represented as logso4l8i(M) = 3.60d=0.08. The recommended stability constants (25 C, 0.7 mol kg ionic strength) shown in table 5 are based upon the works of Spedding and Jaffe (1954) and Powell (1974). Following the activity coefficient estimates of Millero and Schreiber (1982) and Cantrell and Byrne (1987a), lanthanide sulfate stability constants, expressed in terms of free-ion concentrations, were calculated as log 504 1 = log SO4/3 - 1.67. 

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