Global warming is an issue much talked about for decades. one of the matters related to this issue is the greenhouse effect. The greenhouse effect occurs as due to trapped greenhouse gases in the atmosphere, thus forming a reflection layer that prevents the heat out of the earth. This resulted in an increase in surface temperature of the earth. Carbon dioxide (CO2), one of the greenhouse gases are the dominant cause of global warming with emissions growth reached more than 28 Gton / year.
(Source: Green chemistry: Designed to dissolve, Nature 2000)
For most people, the scourge of CO2 greenhouse effect caused. However, behind the negative impacts, CO2 can provide benefits to the development of technology. From the characteristics of the CO2, which has a relatively low critical point (Tc = 31.1oC, Pc = 73.8 bar). The low CO2 critical point in the process offers many advantages pemanfaatanya
In the conditions above the critical point, CO2 is in supercritical conditions so that better known as supercritical carbon diokida (supercritical CO2). Operational conditions which are often used in the industrial world soon is in the range of temperatures below 200oC and pressure ranges under 400 bar. Viewed from a critical point which is owned, CO2 can reach supercritical conditions at temperatures and pressures are relatively low so that operationally require only a relatively small cost
Supercritical CO2 has very unique characteristics: a density like liquid and also have capabilities such as gas diffusion and also has a value of zero surface tension. From this the uniqueness of supercritical CO2 can be used as alternative solvents in various processes. With such density liquids, supercritical CO2 can be used as a substitute for organic solvents.
The ability of diffusion / penetration such as gas, supercritical CO2 can be removed / evaporated from the material without leaving a residue. With low surface tension, supercritical CO2 can make contact with perfect tehadap other materials. In addition, economic benefits from the use of CO2 is a relatively cheap price (less than $ 0.5/kg).
DeSimone is that many researchers develop research berkaian with the use of supercritical CO2. In 1992, DeSimone managed to synthesize the fluoropolymer (eg Teflon) using supercritical CO2. He also succeeded in synthesizing the copolymer (a polymer composed of 2 types of monomers) class of fluoropolymer with the same method. The applicability of supercritical in the process of synthesizing the solvent shifts the use of CFCs (Chloro Fluoro Carbon) which had a negative impact on ozone depletion
In addition, with MiCell Technologies, he developed a dry cleaning system is safe by using supercritical CO2. In the dry cleaning system developed, the process of cleaning done dengn principle of extraction / separation with supercritical CO2 as a solvent.
Supercritical CO2 to replace tetrachloroethylene used as a solvent in dry cleaning process since the 1940s. Tetrachloroethylene has a very good cleaning power, stable, and non-flammable. However, the compound is a group of carcinogenic compounds. The use of supercritical CO2 gives a positive meaning for the decline in the use of carcinogenic compounds.
In the food industry, supercritical CO2 can also be used to separate compounds that are not needed by the human body. Supercritical CO2 can be separates the caffeine from coffee without compromising the distinctiveness of the aroma of coffee itself. Indonesia is a country rich in natural resources that contain active compounds that are useful for human life. Supercritical CO2 can be used as a solvent alternative "green solvents" nTo extract / retrieve compounds - the active compound that can be used for human life.
In biomedical fields, the process - the process of manufacture, modification of polymer - polymer has begun to shift from the use of organic solvents to the use of supercritical CO2. Utilization of this field is based on the nature of supercritical CO2, which has the characteristics of the gas. In biomedicine, porous materials needed to be a growing medium of cells in the human body. With the ability of diffusion / penetration such as gas, supercritical CO2 can easily fit into the polymer material to form pores. With characteristics such as gas, supercritical CO2 can easily get out of biomedical materials so that the product - biomedical products do not contain residual solvents such as often occurs in the use of organic solvents.
In the field of biopolymer, began to develop research-making processes or the modification using supercritical carbon dioxide. Recent developments, Biomaterials Research Center, Korea Institute of Science and technology have combined to optimize the use of supercritical CO2 with a little organic solvents to process biopolymer modification polilaktida. The system developed is known as supercritical CO2-solvent (Supercritical CO2-solvent system). Biopolymer modification products are known as stereokomplek polilaktida which has a higher melting point polilaktida 50oC than usual. Stereokomplek polilaktida formed by the interaction between poly D-lactide with poly L-lactide.
In these systems, the weakness of supercritical CO2 to dissolve the biopolymer polilaktida addressed with the addition of a little organic solvent. System can successfully shift the method - the method commonly used in the manufacturing process stereokomplek polilaktida, such as solution casting method (with organic solvents) and melt blending (polymer melting process). Method - a common method used is very difficult to produce stereokomplek polilaktida 100% especially in polilaktida with molecular weight above 100 000 g / mol. Supercritical CO2-solvent method worked perfectly to produce stereokomplek 100%.
It's true if everything on earth has always had the benefit if we want to study them. Similarly, greenhouse gas (CO2), behind the threat of negative effects that can be generated, there are many things that can be utilized from the greenhouse gas
11:41 PM
iskandar sensei
Posted in: linux
