Green Chemistry and Biosurfactant Research - Biosurfactants: Research Trends and Applications - page 7

Richard A. Brown Jr. for his work on reactions carried out in ionic liquid and
supercritical fluids (Kidwai and Mohan, 2005). Free-radical polymerization of
methyl methacrylate in water-soluble ionic liquids and cationic ring-opening
polymerizations of 2-( m -diluorophenyl)-2-oxazoline and 2-phenyl-2-oxazoline
in water-soluble ionic liquids performed by Sanchez et al. (2007) are examples
where success has been achieved.
Other solvents : Ester solvents are actually the largest group of green solvents.
Special solvents, such as glycerol carbonate, can be used as nonreactive diluents
in epoxy or polyurethane systems. Ethyl lactate has been reported as a photo-resist
carrier solvent and a cleanup solvent in microelectronics and semiconductor manu-
facturing, and 2-ethylhexyl lactate can be used as degreaser and as a green solvent
in agrochemical formulations, for example, for the protection of paddy rice crops.
Another innovative discovery is the recently developed “switchable solvents” by
Jessop, Liotta, Eckert, and others (Liu et al., 2006). Such solvents change their prop-
erties with different needs. Besides these solvents, other synthetic solvents such as
fluorous and property-changing soluble polymer systems (Bergbreiter, 1998) have
been evaluated as potential green alternatives.
Biocatalysis : The area of catalysis is sometimes referred to as a “foundational
pillar” of green chemistry. The search for new, efficient, and environmentally
benign processes for the textile and pulp and paper industries has increased inter-
est in these essentially “green” catalysts, which work with air and produce water
as the only by-product, making them more generally available to the scientific
community. Laccases (EC 1.10.3.2, p -diphenol: dioxygenoxidoreductase) belong
to the so-called blue-copper family of oxidases. They are glycoproteins, which
are ubiquitous in nature—they have been reported in higher plants and virtually
every fungus that has been examined for them. At present, the main technologi-
cal applications of laccases are in the textile, dye, or printing industries—in pro-
cesses related to decolorization of dyes (Claus et al., 2002)—and in the pulp and
paper industries—for the delignification of woody fibers, particularly during the
bleaching process (Bajpai, 1999).
Design of safer chemicals : Design for reduced hazard is a green chemistry prin-
ciple that is being achieved in classes of chemicals ranging from pesticides to
surfactants, from polymers to dyes. Surfactants (Bayer) and polymers (Donlar
Corporations, 1996; Cargill, 2001) have been developed to degrade in the environ-
ment at the end of their useful lifetime. Dyes without heavy metals (Freeman and
Edwards, 2000) are finding applications in the textile industry. BSs and bioemulsi-
fiers are a novel group of molecules and among the most powerful and versatile
bioproducts that the modern microbial biotechnology can offer. Hence, in the fol-
lowing section, we discuss some roles and applications of these microbial com-
pounds in oil-related sciences, food industries, bioremediation technologies, and
other related fields presenting the processes that exploit commercially available BS
technologies and highlighting those in which they may be potentially applied and
have a greater impact in the near future.