Brines metal complexes

Bischoff, J.L., Radke, A.S. and Rosenbauer, R. (1981) Hydrothermal alteration of graywacke by brine and seawater rocks of alteration and chloride complexing on metal solubilization at 200°C and 350°C. Econ. GeoL, 76, 659-676. 

Complexing Agents. Delayed gelation can be achieved by adding complex-ing agents to the mixture. The metal ions are initially complexed. Therefore all components of the gelling composition can be injected simultaneously. It is possible to dissolve the mixture in produced brines that have high salinity. The use of produced brines eliminates the need to treat or dispose of the brines. 

Interactions of Metal Salts with the Formation. Interactions of metal salts with the formation and distribution of the retained aluminum in a porous medium may significantly affect the location and strength of gels. This interaction was demonstrated with polyacrylamide-aluminum citrate gels [1514]. Solutions were displaced in silica sand. The major findings of this study are that as the aluminum-to-citrate ratio increases, the aluminum retention increases. Furthermore, the amount of aluminum retained by silica sand increases as the displacing rate decreases. The process is reversible, but the aluminum release rate is considerably slower than the retention rate. The amount of aluminum released is influenced by the type and the pH level of the flowing solution. The citrate ions are retained by silica sand primarily as a part of the aluminum citrate complex. Iron, cations, and some divalent cations cannot be used in the brine environment. 

Boyle EA(1981) Cadmium, zinc, copper, and barium in foraminifera tests. Earth Planet Sci Lett 53 11-35 Brugger J, McPhail DC, Black J, Spiccia L (2001) Complexation of metal ions in brines application of electronic spectroscopy in the study of the Cu(II)-LiCl-H20 system between 25 and 90°C. Geochim Cosmochim Acta 65 2691-2708... 

Complexation of metal cations and transport in ore-forming solutions derived from sedimentary basins by organic acid anionic complexes present in oil field brines... 

The elements of group I (Li, Na, K, Rb, Cs, Fr) are collectively known as alkali metals. They occur in nature only as +1 ions. They are the most electropositive in nature and their compounds are most ionic. The salts of alkali metals are quite soluble in water and thus they are found in large quantities in water and salt deposits which have formed by the evaporation of brine. However many in soluble clays also contain alkali metals as complex metal silicates. 

The analysis of brines perhaps deserves special mention as the high sodium chloride concentrations are extremely unfavourable for electrothermal atomisation and most troublesome in flame analysis. The preferred approach is probably solvent extraction with either oxine or APDC to remove the trace metals into a small volume of MIBK for flame atomisation or chloroform for electrothermal cells. Care must be taken to avoid interference from chloro-complexes in the extraction, and if this is suspected an ion-association extraction of these complexes might be preferable. 

It should be noted that the complexity and ill definition of carbonate salts in highly saline solutions is documented in literature by the complete absence of single salt osmotic and activity coefficient data. This situation requires the use of this less than satisfying technique to define heavy metal chemistry in brines. 

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