Complex metal sulfates

OC-Hydroxycarboxylic Acid Complexes. Water-soluble titanium lactate complexes can be prepared by reactions of an aqueous solution of a titanium salt, such as TiCl, titanyl sulfate, or titanyl nitrate, with calcium, strontium, or barium lactate. The insoluble metal sulfate is filtered off and the filtrate neutralized using an alkaline metal hydroxide or carbonate, ammonium hydroxide, amine, or alkanolamine (78,79). Similar solutions of titanium lactate, malate, tartrate, and citrate can be produced by hydrolyzation of titanium salts, such as TiCl, in strongly (>pH 10) alkaline water isolation of the... 

The tetrahydrate loses three hydration waters above 100°C and becomes anhydrous at 380°C. Many complex sulfates are formed with aLkah-metal sulfates. 

Exciting developments have occurred in the coordination chemistry of the alkali metals during the last few years that have completely rejuvenated what appeared to be a largely predictable and worked-out area of chemistry. Conventional beliefs had reinforced the predominant impression of very weak coordinating ability, and had rationalized this in terms of the relatively large size and low charge of the cations M+. On this view, stability of coordination complexes should diminish in the sequence Li>Na>K>Rb> Cs, and this is frequently observed, though the reverse sequence is also known for the formation constants of, for example, the weak complexes with sulfate, peroxosulfate, thiosulfate and the hexacyanoferrates in aqueous solutions. 

Sulfate process streams are commonly used in metal recovery because they are readily derived by leaching with sulfuric acid or by oxidation of sulfidic ores. Metal recovery from such streams rarely involves the formation of metal sulfate complexes because the sulfate ion is a weak ligand for base metal cations and consequently acidic ion exchange extractants are commonly employed (see Section 9.17.5), which generate sulfuric acid which can be returned to the leaching stage,... 

The separation of the two stages is easier to discern when the rates of the two processes are so different, but it can also be seen in the ultrasonic spectra of metal-sulfate systems (Sec. 3.4.4). Ultrasonic absorption peaks can be attributed to formation of outer-sphere complexes (at higher frequency, shorter t) and collapse of outer-sphere to inner-sphere complexes (at lower frequency). In addition to uv spectral and ultrasonic detection, polarimetry and nmr methods have also been used to monitor and measure the strength of the interaction. There are difficulties in assessing the value of ATq, the outer-sphere formation constant. The assemblage that registers as an ion pair by conductivity measurements may show a blank spectroscopically. The value of Aq at T" K may be estimated using theoretically deduced expres-... 

BF3 reacts smoothly, in inert solvents, with alkali metal sulfates and phosphates to give stable 2 1 and 3 1 complexes (Table 9), whereas the intermediate complexes that form with NOT, SO and COl- decompose to [BF4] and B203.55 Brownstein et al. have established114 that BF3 reacts easily with alkylammonium salts in CH2C12 or liquid S02. [BF3A]- complex anions are formed with the salts of strong acids (equation 17) whereas complexes with salts of weak acids easily undergo disproportionation (equation 18) and/or conversion into a 2 1... 

Wastes containing complexing molecules such as EDTA can be treated by a coprecipitation with ferrous sulfate, ferrous chloride or dithiocarbamate, which is used in conjunction with the regular precipitant, such as sodium-hydroxide. The treatment scheme requires two reaction vessels. Sulfide precipitation can be also used for complexed metals treatment. 

There are two treatability groups of dissolved metals for chemical precipitation, complexed and non-complexed metals. Non-complexed metals can be removed by a direct precipitation with such a chemical as lime (Ca(OH) ), caustic (NaOH), sodium sulfide (Na2S), ferrous sulfide (FeS), or sodium carbonate (NajCOj). Complexed metals require coprecipitation with ferrous sulfate (FeS04), ferrous chloride (FeClj), or sodium dimethyl dithiocarbamate (DTC) in addition to a regular precipitant such as caustic or lime. Electrochemically generated ferrous ion is also effective in removing a wide variety of heavy metals, including hexavalent chromium. 

Wastewaters containing complexed metals with a strong complexing agent such as EDTA, ammonia, or citrates require a two step precipitation for the metal removal. A continuous process using ferrous sulfate or ferrous chloride is as follows ... 

Aluminum can accept two electrons to complete its octet. The pair of electrons is available from the halogen. An alkali halide can supply the electrons and form a complex (c), or the electron pair may come from the halogen of another aluminum chloride. Association with other aluminum halides accounts for the higher melting point of aluminum halides over antimony(lll) halides which have a formula weight of 95 or more. The association of aluminum sulfate, alkali metal sulfate, and water to form the stable alums is one of the more complex examples. 

Lewis Acid-Complexed Metal Salts. Mixtures of aluminum chloride and metal chloride are known to be active for the isomerization of paraffins at room temperature.178 Ono and co-workers179-183 have shown that the mixtures of aluminum halides with metal sulfates are much more selective for similar reactions at room temperature. 

Metal cyanides(and cyano complexes), 216 Metal derivatives of organofluorine compounds, 217 IV-Metal derivatives, 218 Metal dusts, 220 Metal fires, 222 Metal fulminates, 222 Metal halides, 222 Metal—halocarbon incidents, 225 Metal halogenates, 226 Metal hydrazides, 226 Metal hydrides, 226 Metal hypochlorites, 228 Metallurgical sample preparation, 228 Metal nitrates, 229 Metal nitrites, 231 Metal nitrophenoxides, 232 Metal non-metallides, 232 Metal oxalates, 233 Metal oxides, 234 Metal oxohalogenates, 236 Metal oxometallates, 236 Metal oxonon-metallates, 237 Metal perchlorates, 238 Metal peroxides, 239 Metal peroxomolybdates, 240 Metal phosphinates, 240 Metal phosphorus trisulfides, 240 Metal picramates, 241 Metal pnictides, 241 Metal polyhalohalogenates, 241 Metal pyruvate nitrophenylhydrazones, 241 Metals, 242 Metal salicylates, 243 Metal salts, 243 Metal sulfates, 244 Metal sulfides, 244 Metal thiocyanates, 246 Metathesis reactions, 246 Microwave oven heating, 246 Mild steel, 247 Milk powder, 248... 

From the above results, the surface structure appears to be S04 combined with Zr elements in the bridging bidentated state, as Okazaki et al. proposed in the case of titanium oxide with sulfate ion (155, 156). The double-bond nature of the complex is much stronger compared with that of a simple metal sulfate thus, the Lewis acid strength of Zr4+ becomes remarkably stronger by the inductive effect of S = O in the complex, as illustrated by arrows in the previous scheme. If water molecules are present, the Lewis acid sites are converted to Bronsted acid sites (129, 151, 157). 

The tank initially contains a Barium-EDTA complex in basic medium (A). EDTA, also written YH4 below, denotes ethylenediaminote-traacetic acid, which is known to complex metallic ions. Even in the presence of sulfate ions (U), the barium-EDTA complex is stable in basic medium. The injection of H+ ions neutralizes the medium, dissociates the complex and causes barium sulfate (S) to precipitate. The reaction scheme may be written as a system of two consecutive competing reactions ... 

The literature on inorganic open-framework materials abounds in the synthesis and characterization of metal silicates, phosphates and carboxylates. Most of these materials have an organic amine as the template. In the last few years, it has been shown that anions such as sulfate, selenite and selenate can also be employed to obtain organically templated open-framework materials. This tutorial review provides an up-to-date survey of organically templated metal sulfates, selenites and selenates, prepared under hydrothermal conditions. The discussion includes one-, two-, and three-dimensional structures of these materials, many of which possess open architectures, The article should be useful to practitioners of inorganic and materials chemistry, besides students and teachers. The article serves to demonstrate how most oxy-anions can be used to build complex structures with metal-oxygen polyhedra. 

The water analyses were coded and then processed with the computer program WATEQ2. This program was modified in several ways to handle acid mine waters (a) the Eh could be calculated from the Fe VFe activity ratio or vice versa, (b) several sulfate minerals were added,(c) metal sulfate and hydroxide complex constants were carefully evaluated and included, and (d) Mn, Cu, Zn and Cd species were added since they are major constituents for several of the water samples. These modifications and the evaluated thermodynamic data are described by Ball, Jenne and Nordstrom in this symposium (32). 

Figure 11. Empirical — aG° data for 1 1 metal sulfate complexes (1 = 0) plotted against z z./(ym + r o J, where z+ and z. are the valence of cation and sulfate ion, Ym is the crystallographic radius in Angstroms of the cation in sixfold coordination (3S), and ysoj, = 3.05 A (59). The locus of — aG° values computed for the complexes by the simple electrostatic model is shown as a dashed line, and computed by the Fuoss and Bjerrum equations as lines labeled (F) and (B), respectively.

Figure 12. Empirical and model-predicted aS° values for 1 1 metal sulfate complexes (1 = 0) plotted against z,z./(i y + (F) Fuoss and (B) Bjerrum models.

The chemistry of actinide ions is generally determined by their oxidation states. The trivalent, tetravalent and hexavalent oxidation states are strongly complexed by numerous naturally occurring ligands (carbonates, humates, hydroxide) and man-made complexants (like EDTA), moderately complexed by sulfate and fluoride, and weakly complexed by chloride (7). Under environmental conditions, most uncomplexed metal ions are sorbed on surfaces (2), but the formation of soluble complexes can impede this process. With the exception of thorium, which exists exclusively in the tetravalent oxidation state under relevant conditions, the dominant solution phase species for the early actinides are the pentavalent and hexavalent oxidation states. The transplutonium actinides exist only in the trivalent state under environmentally relevant conditions. 

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