Other sulphates

Hydrated metal sulphates have long been used to study water removal processes, and characteristic kinetic behaviour is conveniently illustrated by reference to these substances. Frost and co-workers [602,603] have investigated the structures, stabilities and adsorption properties of various intermediate amorphous phases, the immediate reaction products which can later undergo reorganization to yield crystalline phase. 

Measurements of the kinetics of the individual nucleation and growth steps in the reactions of several hydrated sulphates have been referred to in Sect. 1.2 though, perhaps surprisingly, these data were not combined in a kinetic analysis for the overall reaction in studies of the alums [51,431, 586] or NiS04 7 H20 [50]. Indeed, Lyakhov and Boldyrev [81], in one of the few reviews of the field, maintain that the satisfactory topochemi-cal description of dehydrations is a problem which at present remains 

The dehydration and interconversion reactions of the various forms of calcium sulphate [dihydrate, hemihydrate (a and 3 pseudo morphs) and anhydrous salt (hexagonal and orthorhombic structures)] have been studied by Ball et al. [281,590,591] who compared their observations with the available rate and microscopic data. The important features of the complicated behaviour found are summarized in the scheme [281] 

More detailed consideration of the sensitivities of dehydration rates to reaction conditions (PH2o temperature) are given in the articles cited reported values of E, at various PH2Q, are summarized in Fig. 13. From kinetic observations, it was concluded that between 353 and 383 K, the dehydration of CaS04 2 H20 [590] involved nucleation ( in Fig. 13) and boundary control (o) but for 383—425 K, a diffusion mechanism ( ) operated. The kinetics of dehydration of a-CaS04 ] H20 [590] (X,+) 

These lead to more or less severe corrosion of aluminium, depending on the nature of the salt and its concentration. 

Iron (n) sulphate FeS04-7H20 in saturated solution has only a slight action in aluminium at room temperature, and it is, therefore, possible to transport and to store ferrous sulphate solutions in aluminium vessels. However, as soon as ferrous sulphate oxidises to ferric sulphate, the medium becomes very aggressive towards aluminium. 

---

Kieserite bed.-—-Resting on the polyhalite bed is a layer of rock salt, sometimes 100 feet thick, mixed with layers of kieserite, MgS04.H20, and other sulphates, approximating on the average 65 per cent, of rock salt 17 per cent, of kieserite 13 per cent, of camallite, KCl.MgCl2.6H20 3 per cent, of bischofite and 2 per cent, of anhydrite. 

Sulphates of the alkali and alkaline earth metals, when heated with sulphur, are converted into sulphide, polysulphide and thiosulphate, with simultaneous formation of sulphur dioxide many other sulphates, e.g. those of copper, mercury, silver and lead, yield only sulphide.7 Other salts of the metals behave in a similar- manner, undergoing transformation into sulphides, the change being effected more readily with the salts of the heavy metals, many of which indeed react slowly with sulphur even at 100° C. in the presence of water.8 At 150° to 200° C. mercuric, stannic and ferric salts in aqueous solution are quantitatively reduced by sulphur mercurous, cupric, bismuth and lead salts arc slowly but quantitatively precipitated as sulphides. Nitrates, permanganates and iodates cause oxidation of the sulphur to sulphuric acid. 

All other sulphates are soluble in water, and can therefore be prepared by one of the usual methods, such as treatment of the oxide, carbonate, or metal with the acid. Dilute sulphuric acid dissolves magnesium, zinc, cadmium, aluminium, chromium, iron, manganese, nickel, and cobalt other metals resist its attack, because their electroaffinity is less than that of hydrogen. The order is Cs, Rb, K, Na, Li, Ba, Sr, Ca, Mg, Al, Mn, Zn, Cd, Cr, F e, Co, Ni, Pb —H Cu, Hg, Ag, Pt c., Au. All the metals to the left of hydrogen in the table are attacked, because they receive their ionic charge from the hydrogen... 

Sulphates of the alkali- and alkaline-earth metals are stable at all temperatures lower than that of the electric arc but all other sulphates decompose, the primary product being the oxide of the metal and sulphuric anhydride the latter, however, being unstable at a red-heat, decomposes partly into sulphur dioxide and free oxygen. This decomposition is made use of in the preparation of Nordhausen sulphuric acid, a fuming liquid, consisting chiefly of H2S207 it is made by distilling partially dried ferrous sulphate from fireclay retorts 2 Fe S 04 = Fe2 Oa + S 02 + S 03 the... 

For the sake of illustration it may be mentioned that of the alkali halides only those of lithium give stable hydrates at room temperature. There are also numerous cases in which the sodium salt gives hydrates or is hygroscopic, in contrast with the corresponding potassium compounds, among others, sulphate, nitrate. 

The existence of strong catalysis by some bivalent anions (carbonate, phosphate, succinate, maleate, citrate, phthalate) but not others (sulphate, oxalate, fumarate, isophthalate) has been claimed and attributed to the formation of carbamoyl derivatives of the anion. 

Atkins and Gingerich (7) have observed the infrared and Raman spectra of matrices at 12 K. Five of the eleven fundamental frequencies were observed in this work. Good agreement exists between these observations and the frequencies adopted by Gurvich et al. (6). The two other sulphate-ion group fundamentals are taken from the Raman study of Davies and Sandford (9). The low-frequency fundamentals involving the metal atoms are taken from the infrared study of Belyaeva et al. (8). These authors observed the spectra of K SO, Rb SO and Cs SO isolated in Ar, Kr, and Xe matrices... 

All the phenomena mentioned above are due to the presence of sulphate anions (or SO3) the type of cations to which the original sulphate anions were bound is not critical. Similar phenomena /ill therefore arise when using other sulphates, for example, BaS04, CaS04 etc., for glass melting. 

The various playa environments include a central salt crust or saline pan, composed of dry salt, commonly halite (Figure 10.3D, E), but in some cases trona (Eugster, 1970), gypsum (Stoertz and Ericksen, 1974) or other sulphates such as mirabilite, epsomite or bloedite. The saline mudflat is typically moist clay to silt with surface salt efflorescences and intrasediment (displacive) evaporite minerals. In some systems, these may be zoned on a broad scale, with more-soluble minerals towards the lowest central portion of the mudflat, caused by groundwater evaporation gradients (e.g. Saline Valley, California Hardie, 1968). 

Lauenstein, Friedrich and Haberland investigated the effects of the parenteral administration of heparin, sodium polyethylene sulphonate and a number of other sulphated polysaccharides on oedema of the rat-foot produced by Zymosan . Two heparin preparations were almost inactive but a heparinoid derived from fungal mycelium exhibited marked effects unaltered by adrenalectomy. These authors conclude that it is unlikely that the anti-inflammatory effects of heparinoids are dependent on anticoagulant activity. 

D. Other sulphated compounds (common or commercial names in brackets)... 

This retarding effect is likewise found with other sulphates ... 

Further sulphate addition can now occur, at C-6 of the hexosamine residues and C-2 of iduronosyl groups. There appears to be no obvious requirement for one of these to precede the other, though both occur in a non-random fashion. It is not clear just when other sulphate esters, such as those sometimes found at C-3 of hexosamines, are added, but it is likely to be at much the same time as C-2 and C-6-sulphation.. 

Strontium can also originate from diagenetic processes bacterial sulphates reduction, dissolution and recrystallization - they may favour the liberation of strontium ions from the sulphate and could locally form higher concentrations within the other sulphate rocks... 

Acid. The sulphate group is removed with liberation of a hydrogen ion, as with other sulphates, and the ester linkage is also hydrolysed, with formation of fatty acid and glycerol. 

With a glyceride sulphate and any other sulphate together, this is the simplest approach. 

The subject of the present review stems from the discoveries of A. Fischer and E. Jorpes. Fischer demonstrated that heparin binds or complexes with proteins and other bases and so modifies their biological activity. As a result, hef>arin is able to release or activate enzymes such as lifK)protein lipase, to inhibit hormones such as cortisone and aldosterone , to detoxify toxic agents , and to bind histamine in body cells . Jorpes discovered that heparin is a highly sulphated polysaccharide and that it gives a specific colour reaction with dyes the metachromatic reaction. This resulted in (i) the association of heparin with the naturally occurring mucofK)lysaccharides (ii) the preparation of other sulphated px>lysaccharides, heparinoids (iii) the identification of the mast cells as heparinocytes. 

---