Unfortunately, the acceptance of this application seems to stagnate with little
growth since 2013 due to the lack of re-filling stations for L-CO 2 .
Linde promotes CO 2 as cooling medium for AIRCO systems, e.g., in cars and
cooling systems in supermarkets (see, Linde brochure on R744) [12].
In life science blends of 10% Ethylene oxide and 90% CO 2 are used for cold
sterilization applications [13].
8.3.8 Fire Extinguisher
CO 2 is used as fire extinguisher for both consumer use and industrial applications.
CO 2 smothers fires by preventing the contact of air (and thus oxygen) with combustible matter without damaging or contaminating materials and is used especially
when water is ineffective or undesired. Noteworthy, CO 2 evaporates without
leaving traces.
8.3.9 Water Treatment
It is worth to recall that in such application CO 2 is converted into its hydrated
forms, which originate hydrogencarbonate anion and carbonate dianion (Fig. 6.9).
Such equilibria depend on the pH of the solution and are fully reversible, in
principle CO 2 could be recovered. The use of CO 2 is in quite different directions: i.
Water remineralisation, ii. Industrial water treatment, iii. Well rehabilitation, iv.
Water desalinization.
i. Soft surface waters or desalted waters or highly soft waters from desalination
plants require remineralization in order to adjust their calcium content. In
modern water works, CO 2 is used together with lime to raise the hardness of
such soft waters to be used as drinking water. Also, at the right pH (>10), the
mentioned treatment allows the formation of a protective surface layer of
CaCO 3 in water-mains pipes (a negative fact in boilers), thus avoiding corrosion and improving water quality by slow solubilization of the deposited
carbonate which solubilization is eventually fastened by adding further CO 2 to
water. Remineralization makes these soft waters healthier and tasty. CO 2
addition as a way to maintaining the quality of tap water is also commonly
used in Japan.
ii. Some industries produce large volumes of alkaline waste water. Iron and steel,
textile and dying, pulp and paper, glass bottle washing at beverage filling
plants, and many more create effluents with a pH value above 11. Such waters
cannot be discharged in natural basins (lakes, rivers, sea). To lower the pH,
sulphuric acid has been used for long time which requires careful handling
(avoiding surplus that would produce highly aggressive acid waters) and is
noxious. Carbon dioxide can be used instead for treatment of such waste water
streams. Noteworthy, CO 2 would generate two buffer systems: H 2 CO 3 /HCO 3
−
8.3 Uses of CO 2 and Its Quality
133
growth since 2013 due to the lack of re-filling stations for L-CO 2 .
Linde promotes CO 2 as cooling medium for AIRCO systems, e.g., in cars and
cooling systems in supermarkets (see, Linde brochure on R744) [12].
In life science blends of 10% Ethylene oxide and 90% CO 2 are used for cold
sterilization applications [13].
8.3.8 Fire Extinguisher
CO 2 is used as fire extinguisher for both consumer use and industrial applications.
CO 2 smothers fires by preventing the contact of air (and thus oxygen) with combustible matter without damaging or contaminating materials and is used especially
when water is ineffective or undesired. Noteworthy, CO 2 evaporates without
leaving traces.
8.3.9 Water Treatment
It is worth to recall that in such application CO 2 is converted into its hydrated
forms, which originate hydrogencarbonate anion and carbonate dianion (Fig. 6.9).
Such equilibria depend on the pH of the solution and are fully reversible, in
principle CO 2 could be recovered. The use of CO 2 is in quite different directions: i.
Water remineralisation, ii. Industrial water treatment, iii. Well rehabilitation, iv.
Water desalinization.
i. Soft surface waters or desalted waters or highly soft waters from desalination
plants require remineralization in order to adjust their calcium content. In
modern water works, CO 2 is used together with lime to raise the hardness of
such soft waters to be used as drinking water. Also, at the right pH (>10), the
mentioned treatment allows the formation of a protective surface layer of
CaCO 3 in water-mains pipes (a negative fact in boilers), thus avoiding corrosion and improving water quality by slow solubilization of the deposited
carbonate which solubilization is eventually fastened by adding further CO 2 to
water. Remineralization makes these soft waters healthier and tasty. CO 2
addition as a way to maintaining the quality of tap water is also commonly
used in Japan.
ii. Some industries produce large volumes of alkaline waste water. Iron and steel,
textile and dying, pulp and paper, glass bottle washing at beverage filling
plants, and many more create effluents with a pH value above 11. Such waters
cannot be discharged in natural basins (lakes, rivers, sea). To lower the pH,
sulphuric acid has been used for long time which requires careful handling
(avoiding surplus that would produce highly aggressive acid waters) and is
noxious. Carbon dioxide can be used instead for treatment of such waste water
streams. Noteworthy, CO 2 would generate two buffer systems: H 2 CO 3 /HCO 3
−
8.3 Uses of CO 2 and Its Quality
133