Carbonate aqueous chemistry

The starting point for the aqueous chemistry of caicium carbonate is its soiubiiity product ... 

TABLE 8.12 Some Aqueous-Phase Carbonate / Bicarbonate Chemistry ... 

Thus, after a good deal of complicated aqueous chemistry, we have separated Cu, Ni, and Co ions from one another. Reduction of the ions to the metals is described in Section 17.6. A more recent version of the ammonia leach process uses an ammonia/ammonium carbonate, rather than sulfate, buffer solution. 

The aqueous chemistry of zirconium is complex and dominated by hydrolysis. One aspect is that polymerization takes place when salt solutions are diluted. The polymeric species can be cationic, anionic, or neutral. Polymers that are formed include ammonium zirconium carbonate, zirconium acetate, and zirconium oxychloride. 

It is not our intention to present an exhaustive review of this important subject. Up-to-date reviews are provided elsewhere [38,37]. The classic review by Garten and Weiss [41 ] offers an excellent historical perspective. We do need to summarize here the issues that are essential for understanding the aqueous-phase adsorption phenomena. The main features of carbon surface chemistry are presented first and the con.sequent acid/base behavior of carbons is briefly discus.sed to illustrate their amphoteric character. In Section III it is shown that these phenomena often govern the adsorption of most inorganic compounds. In Section IV we argue that these phenomena can be dominant in the adsorption of organic compounds as well, but they are more often only a part of the whole story. 

FIG. 2 Macroscopic representation of the features of carbon surface chemistry that are thought to be sufficient for understanding aqueous-phase adsorption phenomena. 

The brief review of the vast literature on the phenomenological aspects of adsorption of aromatic solutes has highlighted studies that provide clues, either explicitly or implicitly, to the optimization of carbon surface chemistry for removal of specific pollutants from aqueous streams. Here we make an attempt to synthesize the available information. In Section V we then offer suggestions regarding a comprehensive model of adsorption of organic (and inorganic) solutes. 

A voluminous literature exists on the acidic surface groups and their characterization. Therefore, this aspect of carbon surface chemistry can be here treated relatively briefly. The acidity of these groups opens a convenient way for their determination by titration with aqueous or alcoholic bases. The total of the Bronsted acids, including phenols, reacts with aqueous sodium hydroxide solutions by neutralization adsorption, while carboxylic acids are neutraflzed already by the weak base sodium hydrogen carbonate carboxylic anhydrides (lactones). Lactones and lactols are opened to the carboxylate form by the stronger base... 

Li, L., QuirJivan, P.A., and Knappe, D.R.U. (2002). Effect of activated carbon surface chemistry and pore structure on the adsorption of organic contaminants from aqueous solution. Carbon, 40, 2085—100. 

Pendleton and coworkers [46] showed (Fig. 25.5) that the adsorption of dodecanoic acid on different activated carbons linearly decreased when the oxygen content of the carbonaceous adsorbent increased and that the adsorption was not related to the micropore volume of the adsorbent. They concluded that the surface chemistry more accurately predicted the adsorption of dodecanoic acid in aqueous phase compared with the surface area or micropore volume. In addition, carbon surface chemistry also had a significant influence on dodecanoic acid adsorption kinetics. Thus, the adsorption rate was reduced by the high surface oxygen content of the carbon adsorbent, whereas its pore volume made a smaller contribution [47],... 

VEY/DUP] Veyland, A., Dupont, L., Rimbault, J., Pierrard, J.-C., Aplincourt, M., Aqueous chemistry of zirconium(IV) in carbonate media, Helv. Chim. Acta, 83, (2000), 414-427. Cited on pages 210, 351. 

Boakye, E., R.S. Hay, and M.D. Petry. 1997. Mixed carbon-alumina oxide coatings from aqueous sols and solutions. Pp. 363-368 in Aqueous Chemistry and Geochemistry of Oxides, Oxyhydroxides, and Related Materials, J.A. Voigt, T.E. Wood, B.C. Bunker, W.H. Casey, and L.J. Crossey (eds.). (Materials Research Society Conference Proceedings, Vol. 432). Pittsburgh, Pa. Materials... 

Water, the most common and most important solvent on Earth, occupies its position of importance because of its abundance and its exceptional ability to dissolve a wide variety of substances. Coral reefs are a striking example of aqueous chemistry at work in nature. Coral reefs are built by tiny animals called stony corals, which secrete a hard calcium carbonate exoskeleton. 

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