Seven new biobased surfactant technologies
November/December 2013
- Biobased surfactants continue to gain market share owing to concerns about sustainability and the long-term availability of petrochemical feedstocks.
- New technologies are making it easier than ever to make such products from nonfood feedstocks. Technically, everything that can be made from petroleum-based feedstocks can now be made from biomaterials, with the dream of going 100% bio being limited only by nontechnical factors such as price, reliability of supply, and labeling.
- Here are seven novel biobased surfactant technologies worth noting.
Glucose-based surfactant with calcium chelating properties for hard-water detergency
Feedstock
Glucose, fatty alcohol, amino acids
Synthetic process
Glycosylation, oxidation, coupling
Charge
Nonionic and anionic surfactants
Yield
48% to 88% from the octyl-D-glucopyranosiduronic acid
Solubility
Not determined, higher than the critical micelle concentration (CMC)
Biodegradability
Expected
Interfacial properties/surface tension measurements
γCMC : 32–45 mN m-1 (pH of the solution without acid or base additives)
CMC characteristics
19–32 mmol L-1
Krafft temperature
Not determined
Foaming properties
Medium to good
Chelating ability
Ca2+, Fe3+
Potential applications
- Detergency: some surfactants retain foaming properties even in calcium solutions.
- Fe3+ removal from water phases by a flotation process.
Benefits
- These surfactants are able to foam even in calcium solutions without any usual detergent additives.
- Possible selective removal of Fe3+ from water phases by the flotation process.
Drawbacks
Price.
Citations
Ferlin, N., D. Grassi, C. Ojeda, M.J.L. Castro, A. Fernández-Cirelli, J. Kovensky, and E. Grand, Calcium chelating sugar-based surfactants for hard-water detergency, J. Surfact. Deterg. 15:259–264, 2012
Ferlin, N., D. Grassi, C. Ojeda, M.J.L. Castro, E. Grand, A. Fernández-Cirelli, and J. Kovensky, Synthesis of sugar-based chelating surfactants for metal removal from wastewater, Carbohydr. Res. 343:839–847, 2008
Structure
Contact
Eric Grand eric.grand@u-picardie.fr and José Kovensky jose.kovensky@u-picardie.fr
Amino acid soaps derived from dodecenyl succinic anhydride
Feedstock
The dodecenyl succinic anhydride is obtained from petroleum feedstocks. There is potential to make n-alkyl succinic anhydrides from plant oils. The surfactant is formed by reaction with the methyl ester of glycine to give a monocarboxylate surfactant. The ester can then be hydrolyzed to yield a dicarboxylic acid.
Synthetic process
Amide formation and hydrolysis
Yield
85%
Solubility
Water-soluble at 20°C, but limit not measured
Biodegradability
Not known
Interfacial properties/surface tension measurements
For the monocarboxylate, 28 mN m-1 at pH 7, 40.5 mN m-1 at pH 10. For the dicarboxylate, 28.7 mN m-1 at pH 7and 36.4 mN m-1 at pH 10.
CMC characteristics
For the monocarboxylate, ~2 mmol dm-3 at pH7, 8.3 mmol dm-3 at pH10. For the dicarboxylate. ~1 mmol dm-3 at pH 7 and 100 mmol dm-3 at pH 10
Krafft temperature
Below 20°C, but not measured
Foaming properties
Not measured
Chelating ability
The dicarboxylate surfactant shows a low surface tension (~28 mN m-1 at pH 7) in the presence of ~1 mmol dm-3 of calcium ions at a 1:1 surfactant/calcium ion ratio.
Potential applications
For chelating divalent metal ions
Benefits
A biorenewable material (glycine) is used to make the head group
Drawbacks
Petroleum-based hydrocarbon chain
Structure
Contact
Leslie Dix, les.dix@northumbria.ac.uk
Furan methane sulfonates
Feedstock
Glucose/fructose
Synthetic process
Acid-catalyzed conversion of carbohydrate into furan followed by addition of bisulfite to carbonyl group
Charge
Sodium salt of a sulfonic acid
Yield
60%–98%
Solubility
Good in MeOH
Biodegradability
Should be easily biodegradable
Krafft temperature
Ranges: 77–82° C
Benefits
Mild source of SO3-, product precipitates from solution as white solid
Drawbacks
Limited stability in base
Citation
Kraus, G.A., and J.J. Lee, A direct synthesis of renewable sulfonate-based surfactants, J. Surfact. Deterg. 16:317–320, 2013
Structure
Contact
George A. Kraus, gakraus@iastate.edu
Tannic acid–fatty acid nonionic surfactants
Feedstock
Tannic acid, glycine, benzaldehyde, and fatty acids
Synthetic process
Esterification
Yield
About 85% based on the reactants
Solubility
Completely soluble in water and partially soluble in organic solvents preferably toluene and xylene
Biodegradability
Meets European specifications defining biodegradability (100–85% after 28 days in fresh water)
Interfacial properties/surface tension measurements
35–45 mN m-1 at pH = 7
CMC characteristics
0.18–0.65 mM L-1 at 25°C
Krafft temperature
Over 85°C, depending on the type of fatty acids
Foaming properties
Low-foaming
Chelating ability
Forms metal complexes with transition metals and preferably with Cu, Co, Pb, Hg, and Fe
Potential applications
Biocides
Benefits
In petroleum and domestic applications
Drawbacks
Degrades in a high pH medium (pH over 11)
Citation
Negm, N.A., A.F. El Farargy, I.A. Mohammad, M.F. Zaki, and M.M. Khowdiary, Synthesis and inhibitory activity of Schiff base surfactants derived from tannic acid and their cobalt (III), manganese (II) and iron (III) complexes against bacteria and fungi, J. Surfact. Deterg. 16:767–777, 2013
Structure
Contact for more information
Nabel A. Negm, nabelnegm@hotmail.com
Vanillin-nonionic surfactant
Feedstock
Vanillin, ethanolamine, fatty acid
Synthetic process
Esterification
Yield
About 90% with respect to the reactants
Solubility
Completely soluble in water and partially soluble in organic solvents preferably toluene and xylene
Biodegradability
Meets European specifications defining biodegradability (100–85% after 28 days in fresh water)
Interfacial properties/surface tension measurements
32–42 mN m-1 at pH =7
CMC characteristics
0.1825–1.48 mM L-1 at 25°C
Krafft temperature
Over 57–85°C depending on the type of fatty acids
Foaming properties
Low-foaming
Chelating ability
Form metal complexes with transition metals, preferably Cu, Co, Pb, Hg, and Fe
Potential applications
Biocides
Benefits
In drilling applications
Drawbacks
Cannot resist a high-pH medium (>11)
Citation
Sayed, G.H., F.M. Ghuiba, M.I. Abdou, E.A.A. Badr, S.M. Tawfik, and N.A.M. Negm, Synthesis, surface, thermodynamic properties of some biodegradable vanillin-modified polyoxyethylene surfactants, J. Surfact. Deterg. 15:735–743, 2012
Structure
Contact
Nabel A. Negm, nabelnegm@hotmail.com
Tannic acid-polyethylene glycol nonionic surfactants
Feedstocks
Tannic acid, polyethylene glycols (molecular weight: 400, 600, 1000, and 2000 g mol-1), and fatty acids
Synthetic process
Esterification
Yield
About 85% based on the reactants
Solubility
Completely soluble in water and partially soluble in organic solvents preferably toluene and xylene
Biodegradability
Agree by the European specifications (75% after 28 days in fresh water)
Interfacial properties/surface tension measurements (at what pH)
3.–40 mN m-1 at pH = 7
CMC characteristics
0.2–1.2 mM L-1 at 25°C
Krafft temperature
Over 92°C depending on the polyethylene glycol molecular weight
Foaming properties
Low-foaming
Chelating ability
Forms metal complexes with transition metals and preferably Cu, Co, Pb, Hg, and Fe
Potential applications
Corrosion inhibitors, emulsifiers, and wetting agents
Benefits
In petroleum, tissue, coating applications
Drawbacks
Cannot resist a high pH medium (>11)
Citation
Negm, N.A., A.F.M. El Farargy, D.E. Mohammed, and H.N. Mohamad, Environmentally friendly nonionic surfactants derived from tannic acid: synthesis, characterization and surface activity, J. Surfact. Deterg. 15:433–443, 2012.
Structure
Contact
Nabel A. Negm, nabelnegm@hotmail.com
A flexible process model to estimate the economics of large-scale sophorolipid biosynthesis via fermentation
Note: This technology is not itself a biosurfactant. It is an economic model that can be used to assess the economic feasibility of biosurfactants known as sophorolipids.
Summary
This study developed a process economic model for the fermentative synthesis of sophorolipids using contemporary process simulation software and current reagent, equipment, and supply costs, following current production practices. Glucose and either high-oleic sunflower oil or oleic acid were used as feedstocks, and the annual production capacity of the plant was set at 90.7 million kilograms per year with continuous operation of 24 hours a day for 330 days per year. Major equipment costs and other considerations such as capital, labor, material and utilities costs were included in the model.
The single greatest contributor to the overall production/operating cost was determined to be raw materials, which accounted for 89% and 87% of the total estimated production expenditures for the high-oleic sunflower oil and oleic acid-based fermentations, respectively. Based on this model and yields of 100 g L-1, the cost of large-scale sophorolipid synthesis via fermentation from glucose/high-oleic sunflower oil was calculated to be US$2.95/kg ($1.34/lb) and from glucose/oleic acid to be US$2.54/kg ($1.15/lb).
Feedstock
Sophorolipids can be produced from both triacylglycerol and free fatty acid substrates. Because of this and the preference for 17-hydroxyoleic acid as the hydrophobic moiety in the sophorolipid molecules, two different lipidic carbon sources (high-oleic sunflower oil and oleic acid) were modeled for comparison. In both cases glucose was used as the carbohydrate source.
Synthetic process
Certain yeast species (primarily from the genus Candida) produce sophorolipids when they are grown under favorable conditions. Therefore, the model was based on a fed-batch fermentation protocol that we had developed in our laboratory using whole-cell catalysis and assuming yields of 100 grams of sophorolipids per liter of fermentation medium.
Potential applications
This model will be applied to determine the production costs of sophorolipids compared to other more common petroleum-based surfactants in order to assess the economic feasibility of using sophorolipids in place of or as an additive in industries where surfactants are commonly employed or in niche markets where no comparable alternative currently exists.
Benefits
The major benefit of the model is flexibility. One can introduce new steps or methods into the model, and the economic effects of those alterations can be determined thus helping to optimize production and isolation parameters. In addition, the model can draw attention to the most costly operations, thus helping the design engineer to focus on the areas where cost-reduction may be possible.
Drawbacks
None have been identified.
Citations
Ashby, R.D., A.J. McAloon, D.K.Y. Solaiman, W.C. Yee, and M. Reed, A process model for approximating the production costs of the fermentative synthesis of sophorolipids, J. Surfact. Deterg. 16:683–691, 2013
Ashby, R.D., D.K.Y. Solaiman, and J.A. Zerkowski, Production and modification of sophorolipids from agricultural feedstocks, in Biobased Surfactants and Detergents: Synthesis, Properties, and Applications, edited by D.G. Hayes, D. Kitamoto, D.K.Y. Solaiman, and R.D. Ashby, AOCS Press, Urbana, Illinois, USA, 2009, pp. 29–49
Contact
Rick Ashby, Rick.Ashby@ARS.USDA.GOV