Carbon Dioxide-Metal Carbonate Systems in Chemical Processes and Environmental Applications

摘要

Carbon dioxide and carbonate minerals play important role in the geochemistry of the Earth, industrial processes, and environmental applications. Metal carbonates, like CaCO{sub}3, ZnCO{sub}3, PbCO{sub}3, and CdCO{sub}3 are sparingly soluble electrolytes. Carbon dioxide gas can be used to dissolve metal carbonate (M{sup}(2+)CO{sub}3){sup}(2-) type salts or precipitate M{sup}(2+)Cl{sub}2 salts as carbonate salts. These methods utilize the weak acid character of CO{sub}2 in dissolution and common anion feature in precipitation. The multiphase thermodynamic analysis shows how speciation and solubilities change as a function of temperature, pressure, composition, and pH. For designing new chemical processes rigorous models and sound measurements are required to affect the ever-smaller input of chemicals, raw materials, water, and energy. New industrial applications include treatment of waste- and process waters as well as recovering valuable or environmentally harmful metal ions as carbonates. Best available techniques and continuous improvements are needed to produce new environmentally acceptable, energy-efficient processes with lower CO{sub}2 emissions.