Final Report: ‘Greener’ Surfactants from Bio-based Waste as Efficient Alternatives to Nonylphenol EthoxylatesEPA Grant Number: SU835342
Title: ‘Greener’ Surfactants from Bio-based Waste as Efficient Alternatives to Nonylphenol Ethoxylates
Investigators: Nagarajan, Ramaswamy , Bavishi, Vishal , Chittigori, Joshna , Magaletta, Michael , MohdAris, Zarif Farhana
Institution: University of Massachusetts - Lowell
EPA Project Officer: Nolt-Helms, Cynthia
Project Period: August 15, 2012 through August 14, 2013
Project Amount: $14,994
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet (2012) RFA Text | Recipients Lists
Research Category: Pollution Prevention/Sustainable Development , P3 Challenge Area - Materials & Chemicals , P3 Awards , Sustainability
Surfactants are important active ingredients in cleaning products used in both domestic, industrial cleaning applications and form an essential part of our lives. Cleaning products profoundly impact the health and safety of humans. The current surfactant industry as a whole still heavily relies on petrochemical feed stocks, sometimes harsh and toxic chemical methods for the manufacture. Moreover, after usage most surfactants end up in municipal wastewater streams and find their way into rivers and oceans. Some types of surfactants are not biodegradable or biodegrade to produce more toxic products. For example, despite their excellent cleaning efficiency non-ionic surfactants such as Nonylphenol Ethoxylates (NPEs) degrade into nonylphenols identified as estrogen mimics, disrupting the endocrine systems of aquatic species and humans. NPEs are low cost, widely used commodity surfactant (300,000 tons used in 2010 globally). In order to be successful and widely adopted by the industry, alternatives have to be equivalent or better from cost and performance standpoint while being non-toxic and sustainable. This necessitates the use of low cost, abundantly available feedstock as starting materials. The proposed project uses polysaccharide based waste feed-stock (Fruit waste and algae) from abundantly available, non-petrochemical sources (with no dominant competing food value), to be converted into surfactants using non-toxic surfactants. The project explores efficient conversion of bio-based waste to valued-added cleaning products using methodologies that are in accordance to the principles of green chemistry. The outcome of this project supports the three pillars of sustainability – people, prosperity and planet.
The primary objective of the research is to develop a novel class of ‘greener’ bio-surfactants based on polysaccharides as environmental friendly alternative to NPEs. Specific goals of the first phase of the project are stated in the list below:
- Renewable, non-toxic and biodegradable starting materials were used to synthesize these bio-surfactants. The selected starting materials were low cost and abundantly available polysaccharides that are obtained from fruit waste and algae (i.e. polygalacturonic acid, alginic acid).
- One of the important goals of the project was to demonstrate the synthesis of efficient surfactants using environmentally benign modification methods. Conventional chemical catalyst assisted functionalization methods were compared to more sustainable and efficient microwave assisted synthesis. The hydrophilic modification process is carried out in water thus minimizing or eliminating the use of toxic chemicals or solvents and limiting waste disposal costs.
- The novel polysaccharide-based surfactants were characterized using spectroscopy and surfactant properties (surface tension, critical aggregation concentration, acid/base stability, foamibility) and cleaning efficiency (stain removal, soil re-deposition test) were evaluated. The cleaning efficiency of these surfactants was compared with other commercial surfactants such as NPEs and sugar based Alkyl Polyglycosides (APGs).
- Finally these polysaccharide-based surfactants were also used as ‘drop-in replacements’ in laundry detergent formulations to evaluate viability and as ‘greener’ cost effective replacement for NPEs.
- Polysaccharides (PGA and ALG) were hydrophilically modified with a sulfonate containing amino acid namely taurine using conventional methods (with chemical catalysts) and microwave-assisted method to yield bio-based surfactants.
- Microwave-catalyzed synthesis of polysaccharide-based surfactants could be accomplished without using a coupling agent at 90°C within 15 minutes as compared to 16 hours using chemical synthesis involving conventional heating.
- The amidation process was confirmed using Fourier Transform Infrared Spectroscopy (FTIR) and the degree of substitution (DS) was determined to be around 10% using elemental analysis.
- Water solubility and surface-active properties were significantly improved after modification.
- The polysaccharide-based surfactants showed particularly good cleaning efficiency towards hydrophilic type dirt (i.e. bathroom soil and scum) and good fabric detergency in deionized water. However, in hard water the contaminant removal was less efficient.
- The polysaccharide-based surfactant exhibited low foamibility and were stable in acid and base conditions with no substantial change in surface tension.
- Preliminary lab scale test of these polysaccharide-based surfactants in actual industrial cleaning formulations demonstrated good fabric detergency in hard water concentrations below 200 ppm in accordance to ASTM D4008 - 96.
In phase I, the P3 Team has successfully accomplished synthesis of a novel class of polysaccharide-based surfactants. These bio-surfactants exhibit significantly improved surface- active properties and cleaning efficacy comparable to commercial surfactants such as NPEs and APGs in water with salt concentration below 200 ppm. This novel approach to polymeric surfactants developed by the P3 team has lead to filing of a patent disclosure in March 2013. The surfactant technology has already attracted commercial interest from detergent manufacturers such as Alpha Chemical Service and Chemco Corporation. The team is also working closely with Massachusetts Toxics Use Reduction Institute (TURI).
In phase II, the P3 team would like to further fine-tune and significantly expand the applicability of these polysaccharide-based surfactants in a wide range of cleaning applications Moving forward, scalability studies are essential to ensure commercialization viability. The P3 Team will explore the use of these surfactants in applications where surfactant safety is of paramount importance (e.g. cleaning in close proximity to food/ edible items). Dermal toxicity and biodegradability studies along with life cycle assessment will establish long-term viability sustainability of the product. This would be a significant step towards replacing harmful surfactants such as NPEs in cleaning products.