Alternatives to traditional industrial solvents under investigation
Volatile organic compounds traditionally used in industry as solvents have been a major source of pollution resulting in smogs in our immediate environment as well as contributing to irreparable environmental damage at higher atmospheric levels. The need to remove these primary emissions has been addressed through various EU directives. The aim is to switch from traditional organic solvents to water soluble, poorly volatile, long chain oxygenated organic species such as vinyl ethers and diones. To study the fate of these compounds, research has been carried out assessing their rates of reaction with other atmospheric species such as hydroxide ions, OH, nitrate ions, NO3, and ozone, O3. The reaction between these species is rapid in many cases, resulting in a lifetime of a few hours. This implies that they will react on local and regional scales but global transfer will not occur. It has been shown that vinyl ethers react with OH and NO3 radicals to produce organic formates and formaldehyde. The yields have been quantified, allowing mechanisms to be postulated. The breakdown products are found to react further to form more stable smaller compounds such as aldehydes. Some are further decomposed, and others become hydrated and are taken up into the aqueous phase. The oxygenated solvents being considered as traditional solvent replacements have also been investigated for aerosol formation, another atmospheric problem. This has been observed to occur from the ozonolysis of vinyl ethers and from the reaction with OH. The mechanisms for these reactions are still under investigation. Although the need to replace current industrial solvents is well recognised, it is clear that the alternatives have to be explored in greater detail as to their environmental fate and consequences. Research in this area is ongoing.
