Room Temperature Ionic Liquids as Solvent Media for the Photolytic Degradation of Environmentally Important Organic Contaminants

摘要

The photolytic degradation of an organic contaminant, naphthalene, in l-butyl-3-methylimidazolium hexafluorophosphate has been investigated. The original parent compound could be degraded in this ionic liquid using 253.7 nm UV radiation. Oxygen and the purity of ionic liquid with respect to UV light absorbing compounds had a significant effect on the transformation rate of naphthalene. The addition of oxygen to the naphthalene ring and the rupture of the ring due to direct photolytic effect are discussed as possible reaction pathways that contributed to the transformation of the compound. Intermediate product identification using Electrospray TOF MS, and GC-MS revealed the formation of bicycle[4,2,0]octa-l,3,5-triene, 2'hydroxyacetophenone, and phenol among the stable intermediate products. With the use of non-toxic ionic liquids and further optimization and modification, this process has the potential for further development into a two-step process for extraction of organic pollutants from solid matrices, such as contaminated soils or dredged sediments, using ionic liquids followed by in-situ photodegradation of the organic contaminants in the ionic liquid extractant phase with simultaneous regeneration of the ionic liquids.