Seawater carbon capture

The basic constituent of seashells is calcium carbonate, an insoluble compound formed from calcium ions secreted from the cells of the shellfish and carbonate ions present in seawater. But calcium carbonate is a white solid. The colors of seashells often arise from impurities and metabolic waste products captured in the solid shell as it is formed. Coloration is dictated by both diet and water habitat. For example, some cowries that live and feed on soft corals take on the hue of the coral species. Yellow and red colors often arise from carotenoid pigments such as //-carotene. Light refraction often generates the iridescent mother-of-pearl hues. 

Chlorofluorocarbon (CFC) compounds (Freons ) are important tracers of ocean circulation. Since CFC-11 and CFC-12 were released at different rates, their concentrations as well as their ratios can be used to determine when a water mass left contact with the sea surface over the 50 years since Freons were released into the atmosphere and taken up by the ocean. CFC-113 and carbon tetrachloride are being investigated as additional tracers. Picomole levels of CFCs dissolved in seawater are determined using a gas chromatograph equipped with an electron capture detector. The World Ocean Circulation Experiment (WOCE) Hydrographic Program calls for measurements with a precision and accuracy of 1% and a detection limit of... 

For this base year (1994) the cumulative fossil fuel CO2 emission is 238 10 g CO2—C (Boden 2009) hence, 50 % of the CO2 added to the atmosphere is captured by the world s oceans. The total oceanic dissolved carbonate carbon (Table 2.9) corresponds to 0.028 g as carbon in seawater taking into account the volume of the world s oceans (Table 2.3). The experimentally estimated seawater standard carbonate carbon is 0.0244 g L seawater (Dickson et al. 2007). In the first 200 m of the ocean, the total deposited anthropogenic CO2 (Table 2.82 and assuming that 30% is within this layer) only contributes to 3% to dissolved inorganic carbon (DIC). Hence, it is very difficult to measure trends in the DIC because of manmade changes (see Fig. 2.96). 

A key idea of SONNE is the capture of CO2 from the atmosphere to close the global carbon cycle analogously to the biosphere (Fig. 2.98). According to the fluxes described in Fig. 2.98, the system can be established within a steady state (CO2 flux in = CO2 flux out) or even run in an air abatement mode (CO2 flux in > CO2 flux out). Air capture includes three approaches CO2 capture from ambient air, from seawater and via biomass cultivation (biofarming). All these approaches are interlinked within the global carbon cycle but with different characteristic times. 

The desorption of dissolved CO2 from seawater (being 90 % HCO with a mean total concentration of 2.25 g C L ) could be another approach to closing the carbon cycle (we currently call it seawater capture). Hence, in the case of a technology with 60% desorption efficiency, only 0.07 km seawater must be processed daily to attain the production mentioned above. In our laboratory, an ultrasonic-based CO2 desorption technique has been developed as an alternative to the thermal stripping in the CCS process, and it is not difficult to believe that this technology could be applied to seawater decarbonization. 

Babu P, Kumar R, Linga P (2014) Unusual behavior of propane as a co-guest during hydrate formation in silica sand potential application to seawater desalination and carbon dioxide capture. Chem Eng Sci 117 342-351... 

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