Amino acid based surfactants for dry-cleaning with high-pressure carbon dioxide

The currently most used dry-cleaning solvent is perchloroethylene (PER). Carbon dioxide could be an ideal solvent to replace PER. Amino acid based surfactants have been studied for dry-cleaning with carbon dioxide. For the production of amino acid based surfactants, renewable, low-cost raw materials are used. Furthermore, these surfactants have a low toxicity, are biodegradable and not skin irritating. These characteristics make the amino acid based surfactants attractive for dry-cleaning with carbon dioxide. The amino acid based surfactants give good results for dry-cleaning with liquid CO₂. The surfactant Amihope LL (N-lauroyl-L-lysine) gives the best cleaning-results. An important process parameter using this surfactant is the addition of water. The addition of water is required for sufficient removal of non-particulate soils. However, when no water is added to the system, there is a large increase in particulate soil removal. Therefore, a two-bath process is proposed. The first bath is for particulate soil removal and has optimal conditions for particulate soil removal; the second bath has optimal conditions for non-particulate soil removal. The two-bath process using Amihope LL gives excellent results: the result for particulate soil removal is 84% compared to the results for PER, the result for non-particulate soil removal is 98% compared to PER and the overall result is 92% compared to PER.