New Technologies for Dealing with CO2 Emission and Carbonate Discharge Control Issues Associated with Energy Production.

摘要

Carbonates and bicarbonates as two water contaminants and CO2 as an air pollutant are the byproducts of a number of fossil fuel based energy production processes. It is well known that the eco-environmental impacts of the carbon based compounds are rather negative. Discharge of co-produced waters containing carbonates and bicarbonates can lead to the significant increase of alkalinity and sodicity and eventual degradation of the quality of soils. In addition, many studies have indicated that huge CO2 emission into the atmosphere can result in disastrous climate changes in the future. Therefore, people are increasingly interested in controlling these carbon compounds.;A number of technologies such as ion exchange and electrodialysis have been developed for removal of carbonates and bicarbonates from co-produced waters. However, they are too expensive to be widely used by energy producers, farmers and ranchers. Although many approaches including membrane filtration have been explored for CO2 emission control, their costs are not acceptable to fossil fuel generating companies at all. Therefore, searching cost-effective methods for control of the carbon compounds have attracted many researchers' attentions. New technologies have been developed in this research to overcome the abovementioned challenges. For example, a regenerable solid sorbent (KTi) synthesized with K2CO3 and nanoporous TiO(OH)2 can be used to capture CO2. The CO2 sorption capacity of KTi is about 36 times higher than that of conventional K2CO3. The highest CO2 sorption capacity achieved with KTi is 1.69 mmol-CO2/g-KTi. It should be noted that the theoretical sorption capacity of the KTi can be as high as 3.32 mmol-CO 2/g-KTi. Therefore, the potential and improvement in CO2 sorption capacity with the use of nanoporous TiO(OH)2 is significant. Moreover, nanostructured KTi based CO2 separation (from flue gas) does not need additional high specific-heat capacity and high vaporization-enthalpy H2O. This creates a favorable condition for considerable decrease in energy consumption of CO2 capture in coal-fired power plants. It is expected that all the technologies developed in this research could significantly benefit energy producers, although many works need to be done before they can be commercialized.