Chromium xanthate

Pyridazines form complexes with iodine, iodine monochloride, bromine, nickel(II) ethyl xanthate, iron carbonyls, iron carbonyl and triphenylphosphine, boron trihalides, silver salts, mercury(I) salts, iridium and ruthenium salts, chromium carbonyl and transition metals, and pentammine complexes of osmium(II) and osmium(III) (79ACS(A)125). Pyridazine N- oxide and its methyl and phenyl substituted derivatives form copper complexes (78TL1979). 

Some innovating treatment technologies may be introduced in the treatment of wastewater generated in the aluminum fluoride industry to make its effluent safer. The ion exchange process can be applied to the clarified solution to remove copper and chromium. At a very low concentration, these two pollutants can be removed by xanthate precipitation.24 A combination of lime and ferric sulfate coagulation will effectively reduce arsenic concentration in the wastewater. 

The highest PGM recovery was achieved using collector PM443, which is an amine + ester-modified xanthate. Among the chromium slime depressants evaluated, modified mixtures of organic acids, RQ depressants and a low-molecular-weight polyacrylic acid + pyrophosphate mixture were there. The effect of different chromium depressants on chromium assays of the PGM concentrate are illustrated in Figure 18.7. 

This section describes the structural chemistry of 14 molecular structures, 3 of chromium, 8 of molybdenum, and 3 of tungsten. The only binary xanthate structures are those of chromium, all other structures are at least ternary in nature. For the chromium and tungsten structures, conventional monodent-ate and bidentate coordination modes of the xanthate ligand are found. By contrast, a rich, diverse, and fascinating coordination range is observed for the... 

Only four structures are available for the aluminum-group xanthates. The crystal stmctures of Ga(S2COEt)3 and In(S2COEt)3 (200) are isomorphous with each other and with the chromium analog, Cr(S2COEt)3 (31), which is shown in Fig. 10. Thus, each molecule has crystallographic threefold symmetry and essentially equivalent Ga—S [2.405(2) and 2.465(2) A] and In—S [2.574(1) and... 

Depends on the type of mineralization - contaminants from flotation agents of health concern include chromium, cresols, cyanide compounds, phenols and xanthates... 

Copper(II) and cerium(IV) have been studied as oxidants in acetonitrile. The copper(II)-copper(I) couple has an estimated electrode potential of 0.68 V relative to the silver reference electrode. It has been studied as an oxidant for substances such as iodide, hydroquinone, thiourea, potassium ethyl xanthate, diphenylbenzidine, and ferrocene. Cerium(IV) reactions are catalyzed by acetate ion. Copper(I) is a suitable reductant for chromium(VI), vanadium(V), cerium(IV), and manganese(VII) in the presence of iron(III). For details on many studies of redox reactions in nonaqueous solvents, the reader is referred to the summary by Kratochvil. ... 

Dinuclear niobium sulfido and selenido dithiophosphates, Nb2Q4[S2P(OR)2]4,75,76 (Q = S, Se R = Et) (also xanthates and dithiocarbamates) have been prepared but no crystal structure was reported. Optically active chromium complexes, Cr[S2P(OR)2]3 derived from Z)-borneol and L-menthol, have been described.77... 

To address this concern, several organic and inorganic reagents were evaluated as precipitants for heavy metals in a 10-34-0 (N-P2O5-K2O) fluid fertilizer and WPA. Trisodium trithiocyanuric acid (TMT-15), sodium polythiocarbonate (Thio-Red II), and sodium trithiocarbonate (5% Na2 CS3) precipitated arsenic, cadmium, copper, mercury, lead, and zinc from 10-34-0. Ammonium cyanurate was ineffective in removing cadmium from 10-34-0. Thio-Red II and 5% Na2CS3 precipitated mercury, lead, cadmium, copper, and chromium from WPA. A water-insoluble starch xanthate adsorbed mercury, copper, and lead from 10-34-0 and WPA. Sodium sulfide, sodium polysulfide, and potassium ferrocyanide were tested as inorganic precipitants. The polysulfide was twice as effective as the sulfide alone, and concentrations of less than 10 ppm of arsenic, cadmium, mercury, and lead were achieved in 10-34-0. Ferrocyanide reduced the concentrations of cadmium and nickel to less than 10 ppm in WPA. 

Starch Xanthate Adsorbents. Wing and coworkers (12) reported that insoluble starch xanthate was highly effective in adsorbing iron(II) and chromium(III) from synthetic waste water samples. For example, a pH 3.0 waste water with an initial iron(II) concentration of 27,920 mg/L was treated with the starch xanthate and after stirring for 2 h, the residual iron(II) concentration was found to be <1 mg/L. Similar results were obtained for chromium(III), where the chromium(III) concentration of a synthetic waste water sample at pH 3.2 was reduced from 26,000 mg/L to 3 mg/L after stirring for 2 h with the appropriate amount of starch xanthate. 

WI Starch Xanthate. Research by Wing and others (22, 27-29) has shown that water-soluble (WS) starch xanthates, in combination with cationic polymers to form polyelectrolyte complexes, can effectively remove heavy metals from waste water. To eliminate the expensive cationic polymer and give a more economical method of heavy metal removal, further research by Wing and others (12,30-33) showed that xanthation of a highly crosslinked starch yields a water-insoluble (WI) product that is effective in removing heavy metals from waste water without the need for a cationic polymer. In more recent work, Tare and Chaudhari (34) evaluated the effectiveness of the starch xanthate (WS and WI) process for removal of hexavalent chromium from synthetic waste waters. 

Mercury, copper, lead, and cadmium can be precipitated from 10-34-0 by adding TMT-15. The TMT-15 and Thio-Red II precipitated at least 94% of the copper and mercury present in the 10-34-0 manganese and chromium were not precipitated. The WI starch xanthate adsorbed mercury, copper, and lead from 10-34-0, while the adsorption of arsenic, cadmium, chromium, manganese, and zinc was negligible. 

Pyridazine forms a stable adduct with iodine, with semiconductor properties. " Similar complexes were prepared from iodine mono-ehloride, bromine, and nickel(II) ethyl xanthate. Complexes of pyrida-zines with iron carbonyls and with iron carbonyls and triphenylphosphine have been prepared and investigated. " Complexes of pyridazines with boron trihalides, silver salts, mercury(I) salts, iridium salts, " ruthenium salts, and chromium carbonyls are re-... 

Earlier structural studies of carbohydrates by CD involved introduction of suitable chromophores into the sugar molecule thereby affording derivatives which exibit Cotton effects. These include, among others, xanthates (4-8) or azides (9). Later it was found that some metal ions (10), i.e. copper (11,13), vanadate (14), chromium (15), molybdate (16-22), nickel (23) or cobalt (24,25) ions form complexes with carbohydrates, which show appreciable Cotton effects. 

---