It is well known that ionic liquids (ILs) possess extraordinary characteristics, making them greener solvents with unique properties, which allow processes that would otherwise be difficult or impossible with common solvents to be carried out. In this review, we describe and discuss, in the light of possible future large scale applications, some fundamental studies showing the efficacy of ILs in several “hot” fields, from dissolution and transformation of biopolymers to extraction and capture of important inorganic components (metals) or pollutants (CO₂).