What+Makes+Glycerol+Green?

=What Makes Glycerol Green? =

**There are 6 key properties of glycerol that make it "green ":**
 * Low Toxicity
 * Low Vapour Pressure
 * Low Environmental Impact
 * Availability
 * Easy Handling and Storage
 * Can Be Used with Catalysts

[ 15 ] ** Low Toxicity ** When compared to other green solvents, glycerol has a ** very low toxicity ( **as shown in Table 1 below). One indication of this property is its high Lethal Oral Dose (LD50). 12] Further evidence of glycerol's low toxicity is due to the fact that it is often used in the food industry as a preservative or sweetener. It is used extensively in the pharmaceutical and medical industry and makes a large contribution to personal care products. It is commonly used in toothpaste because of its pleasant taste and its good solubility as well as many other hygiene products such as glycerin soap (used by people with sensitive skin). Glycerol is not only non toxic but helps to moisturize. 10]

Glycerol also shows no indications of causing gene mutations, carcinogenicity or teratogenicity. 11]12

** Low Vapor Pressure ** Glycerol has a vapor pressure of less than 1 mmHg at 50 degrees Celsius, which is considered very low. As seen in Table 1, this value is over 92 times lower than water at the same temperature. 12] This low vapor pressure means that glycerol will produce very low emissions and will have little impact on the environment.

 Glycerol may be released to the environment through various means, but is not viewed a threat. It is nonflammable and appears to be of low toxicity to fish and other wildlife. 11] Glycerol is considered to be highly biodegradable: "A number of biodegradation assays have been carried out with glycerol. In a Closed Bottle test (performed according to OECD 301) 92% biodegradation was reported after 30 days. More than 60% biodegradation measured as ThOD (theoretical oxygen demand) was reached within the 10-day window (Henkel 2001)." 11] This green solvet is also not expected to accumulate in the environment with use, and "the calculated bioconcentration factor is 3.162 (EPIWIN vs 3.04)" [ 11 ]. This value is very low and reveals that the concentration of glycerol in an organism is not much greater than the concentration in the environment. 14]
 *  Low Environmental Impact **

** Availability ** Glycerol is readily available from the current vegetable oil industry, where it is a by-product during the production of biodiesel fuel. It is available at a large scale and is relatively cheap. “0.50 **€**/Kg for pharmaceutical grade (99.9%) and 0.15**€**/Kg for the technical grade (80%)”. (Gu & Jerome, 2010). 17]

21] Due to glycerol's low toxicity and non-corroding behavior, glycerol is easily stored and transported.
 * Easy handling and storage[[image:flexitank.jpg width="241" height="138" align="right"]] **

22] Glycerol can be used as a solvent in certain homogeneous and heterogeneous catalytic reactions used to make a process more green. These reactions can be more environmentally friendly because they don't often require toxic reagents and produce fewer byproducts. This can result in a cleaner and simpler reaction, usually making the process of separation easier. 12]
 * Can be used with catalysts **