Destination Maternity

Design and application of dispersants Dioxide Carbon, improving your character as a solvent in the effort to replace solvents that harm the environment.

Volatile Organic Compounds (VOCs)

VOCs include solvents such as xylene, toluene, benzene, methylene chloride, chloroform and isopropyl alcohol. They are widely used in industry due to their relatively non-polar and is therefore very effective to dissolve oils, waxes and fats. In addition, the average consumer uses a lot of VOCs in their products daily. VOCs are also found in gasoline, paints, glues, paints and household cleaning products. Also emitted during the combustion of fuels (gasoline, oil, wood, coal, natural gas, etc.) Cars being the main source of VOCs.

Halogenated Organic Compounds

Halogenated organic compounds are carbon compounds that contain halogen atoms such as fluorine, chlorine and bromine. The two main classes of these compounds are the chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs). They are generally unreactive, nontoxic and nonflammable. These properties have contributed to its popularity in the use as industrial cleaning solvents. Furthermore, these substances have been widely used as refrigerants, aerosol propellants and blowing agents. The names and formulas of some of the most common CFCs and HCFCs are

CFCs HCFCs
CCl 3 F triclorofluormetano CHF2Cl monoclorodifluormetano
CCl2F2 dichlorodifluoromethane C2HF3Cl2 diclorotrifluoretano

Carbon Dioxide: Solvent alternative to the VOC and halogenated organic compounds, and environmentally preferable

Because of the many negative effects on the environment with the VOC and halogenated solvents, is important to find alternatives to them. Carbon dioxide is presented as an option and offers many advantages when used as a solvent. Is nonflammable, nontoxic and non-reactive and is available as a cheap byproduct recovery in the manufacturing of ammonia and natural gas wells. Besides carbon dioxide once used can be easily recovered, purified and reused.

Unlike CFCs and HCFCs, carbon dioxide does not contribute to the reduction of ozone and VOCs difference is a factor of production of tropospheric ozone.

To consider CO2 as a green alternative to the VOC and halogenated organic solvents, once used should be recycled. The carbon dioxide used as a solvent could be recovered and reused, simply allowing the carbon dioxide becomes supercritical fluid or gas, capturing and leaving behind the less volatile impurities. This recycling process requires very little power as the CO2 exists as a gas under ambient conditions. Compared with organic solvents or water, the enthalpy of vaporization is considerably lower.

Another consideration to take into account when assessing the use of carbon dioxide as a solvent good for the environment, is the source of CO2. As noted previously, carbon dioxide is a waste product in the manufacture of ammonia and natural gas wells and can be recovered from these processes. This avoids the need to produce carbon dioxide, allowing him to good use recovered in the aforementioned processes, and thereby preventing their release into the atmosphere. Many of these factors contribute to carbon dioxide is a green alternative to the VOC and halogenated organic compounds.

As discussed above, the carbon dioxide gas at room temperature and pressure. To use the CO2 as a solvent must be converted to liquid or supercritical fluid. As illustrated in the following phase diagram, carbon dioxide is a supercritical temperature (Tc) of 31 ° C and a supercritical pressure (Pc) to 72.8 atm. Supercritical fluids have properties of gases and liquids. Supercrítco CO2 is currently used as solvent for the preparation of decaffeinated coffee.