Bioprocessing Approaches to Synthesize Bio-based Surfactants and Detergents - Food and Industrial Bioproducts and Bioprocessing - page 236

10 Bioprocessing Approaches to
Synthesize Bio-based Surfactants
and Detergents
Douglas G. Hayes
10.1 BIO-BASED SURFACTANTS: OVERVIEW
The main use of surfactants and detergents is to lower interfacial surface free energy at
liquid-vapor or liquid-liquid interfaces via their interfacial adsorption, with the main goal
being to increase the miscibility of two immiscible liquid phases, or to modify the polarity of
the interface. The molecular structure of surfactants typically consists of separate hydrophilic
and lipophilic domains, which promotes their partition to interfaces. Surfactants, an industry
of approximately 10 million metric tons (tonnes) and US$20 billion in size (Hayes, 2009), are
found in many commercial products: foods, cosmetics, personal care products, cleaners (e.g.,
laundry detergents), pharmaceuticals, paints and coatings, and lubricants to name a few.
A comprehensive review of bio-based surfactants in foods and their specific roles has been
published elsewhere, with “bio-based” referring to derivation from natural and renewable
resources (Kralova and Sjoblom, 2009).
In the early twentieth century and before, surfactants were derived from nature, with the
most common source being fatty acid salts, or soaps, used in personal care products. But as
the availability and utilization of petroleum increased in the 1920s and beyond, this source
became the main feedstock for surfactants. However, due to several motivators: the decreased
availability of petroleum and other fossil fuels, the increased demand, hence price, for
petroleum ($140/bbl reached in 2008), national security concerns about dependency upon
non-domestic petrochemical suppliers, environmental concerns with obtaining fossil fuels
(due to their increasingly difficult accessibility, evidenced by the environmental damage
caused by the leakage of the “Deepwater Horizon” off-shore oil well in the Gulf of Mexico
in 2010, 5600 m below sea level) and the generation of carbon dioxide and other greenhouse
gases (and their impact upon climate change), interest in bio-based surfactants has increased
(Hayes, 2009; Patel, 2004).
Several of these motivators have translated to increased consumer demand for bio-based
and eco-friendly products, motivating surfactant producers and suppliers to seek certification
for the labels “bio-based” or “green” or “eco-friendly” or “sustainable” (McCoy, 2008;
Hayes, 2009). Of note, the feedstock costs will serve as the main economic motivator for
manufacturing bio-based surfactants, since the production cost per mass for bio-based is
roughly equivalent to petroleum-based (US Department of Energy, 1999). Furthermore,
bio-based feedstocks for surfactants must possess reduced price fluctuations and increased