The production of surfactants by combining biomass and microorganisms – such as bacterial agents – is an innovation that is increasingly gaining traction.
Producing surfactants from plant sources dates back many thousands of years. Their increasing popularity in a sustainability-focused world is somewhat a renaissance. The use of enzymes cultivated by microorganisms, however, began around the middle of the 20th century.
It is perhaps true that in our clinically-cleansed post-Covid world, there is a hint of irony in the concept of creating cleaning and personal care products from germs and/or viral microbes. The processes for fermenting, extracting and purifying biosurfactants have demonstrated significant breakthroughs in recent years.The term surfactant means surface-active agent. As an additive, surfactants reduce the surface tension of any liquid in which it is dissolved, essentially by stabilising the substance's oil and water mix.
When it comes to liquids and solids, surfactants serve to reduce interfacial tension. In layman's terms, a surfactant dislodges dirt before re-releasing it into the solution in which it is dissolved.
It is this stabilising property that renders a surfactant useful to end products such as skin cleansers, shampoos, soaps and cleaning detergents.
Global chemicals and energy companySasol– based in South Africa, Germany's BASF and Swiss speciality chemicals company Clariantare focused on renewable surfactants. They are among global producers developing fermentation-based surfactant offerings.
Keen to boost the fossil carbon-free portfolio of its Care Chemicals division, BASF is increasing its sustainable and environmentally-sound surfactant product output strategically.
BASF’s aim is to replacefossil-based feedstocks with biobased alternatives, using high-performance ingredients and enzymes for more efficient, lower water consuming, formulations. Incorporating recycled raw materials – and using waste CO2 as a feedstock – feature in the company's tactic mix.
Already, up to 70% of its Care Chemicals feedstocks are biobased or bioderived, according to the firm. But the goal is to increase that ratio to over 90%. However, Scope 3 emissions largely come from raw materials value chains says the firm.
Replacing traditional formulations
To combat that supply chain challenge, sugar-based surfactants have become more prominent in BASF’s portfolio in recent years. Sugar-based surfactants – such as alkyl polyglycosides (APG), fatty acid glucamides, sorbitan esters and sucrose esters – are also gaining popularity.
APGs are widely used in personal care, home care, industrial and institutional cleaning and agriculture applications. The growing interest is partly due to improvements in their performance characteristics.
They are also more environmentally-friendly and compatible with human health with low toxicity levels – compared to petrochemical-based options.
BASF’s APGs are produced from 100% plant-based feedstocks. They are chemically synthesised from the sugars and fatty alcohols within those raw materials. In June 2023, the company announced plans to increase APG production capacity at key global sites.
Expected onstream in 2025, expansion plans are in place for sites in Thailand and Ohio in the US. From these regional supply points BASF will serve customers faster and more flexibly, while reducing cross-regional volume flows. Less transportation translates to a lower overall carbon footprint is the thinking.
BASF claims to be the sole producer of APGs in North America. It also produces APGs in Dusseldorf, Germany and Jinshan, China, though its global capacity remains undisclosed.
The compnay expanded APG production capacity in Cincinnati. Until five years ago, BASF’s Cincinnati APG production capacity was known to be 25 ktpa, but the firm expanded production to an undisclosed amount in 2018. In the same year, the firm upped its APG output at Jinshan, China to 30 ktpa.
There are a number of other APG producers around the world. They include speciality chemicals company Nouryon, Air Liquide healthcare company Seppic based in France and Seoul, South Korea-basedLG Household & Healthcare. In the Americas, there's materials science company Dow and Brazil's Oxiteno, which is now owned by Indorama.
Industry sources believe there to be a small number of APG producers in China.
BASF has also expanded its biobased surfactant portfolio with fermentation-based surfactants. BASF has a partnership with UK-based Holiferm– founded just five years ago – that is targeting rhamnolipids and mannosylerythritol lipids (MELs). It also has a controlling interest in the Japanese sophorolipids producer Allied Carbon Solutions, which it is leveraging to boosts its surfactant innovations.
Sasol is also exploring fermentation-based surfactants such as sophorolipids, rhamnolipids and MELs with Holiferm. Sasol is looking to scale up its biobased sophorolipids surfactants to 20 ktpa by 2025 using the startup's processes.
Holiferm’s first commercial plant – located in Liverpool, UK – will initially produce around 1100 tons per year of sophorolipids. The company’s semi-continuous process for yeast-based surfactant production has doubled titre and productivity with finished products comprising 60% sophorolipids content.
The process – which uses gravity separation to recover insoluble lipids as they are produced – has cut production costs over 50%. The sophorolipids range will be targeted at cosmetics, homecare, personal care and the Industrial & Institutional cleaning sector.
Holiferm is also in the process of developing other biosurfactant molecules, such as bacterial surfactants - rhamnolipids and yeast-based MELs. The firm currently uses rapeseed oil and dextrose feedstocks – the latter sourced from nearbyAiredale Chemical. It is however, keen to switch to sugar and fatty acid waste streams in the future.
From fossil to biobased
Petrochemical-based surfactants traditionally relied on benzene and ethylene as the basic building blocks. Benzene, an aromatic compound, is a basic raw material for producing the surfactant linear alkylbenzene (also known as LAB).
LABs are the major detergent surfactant workhorse.
The non-aromatic hydrocarbon ethylene is the feedstock for ethylene oxide (EO). Then, a nonionic surfactant is formed from the EO intermediate. Nonionic surfactants are typically used as a grease removal agent in detergents, household cleaners and dish soap.
Common in personal care products is sodium lauryl ether sulfate (SLES) surfactant, which is produced from palm kernel and coconut oils.
As consumers and governements push Environmental, Social and Governance agendas, interest in biosurfactants is likely to grow. According to BASF, over 12 million tons of surfactants are consumed in the production of household detergents and cleaners annually worldwide. BASF estimates the CO2 equivalent emissions at around 40 million tons.
Clariant meanwhile believes that over half the global surfactant market is covered by fossil fuel-based products – LABs and sulfonates included.
Reducing carbon footprint
Brands closer to the consumer are getting in on the act already. Unilever this year unveiled cleaning and laundry product enzymes with better stability, performance and sustainability credentials.
Developed collaboratively with US-based biotech company Arzeda, the UK-headquartered fast-moving consumer goods company claims its new enzymes carry a lower carbon footprint than conventional petrochemical-derived products.
The partnership's innovation combined physics-based protein design and artificial intelligence to create new proteins and enzymes to tackle stains using less household water and energy.
Sasol meanwhile, says sophorolipids' greenhouse gas (GHG) emissions are 80% lower than SLES surfactants and 66% lower than SLES. The firm is expecting significant growth in the biosurfactants sector with projections of global market potential at around 400 ktpa by 2025.
If Sasol – and all the other producers beefing up their biosurfactant portfolios and capacities are correct – this is an area of the chemicals industry that can be said to be approaching sustainability with open arms.
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