26 TRENDING TECHNOLOGIES


to surfactants that are partially or fully based on renewable feedstocks. This material class can be divided into three sub-segments: Partially bio- based surfactants, fully bio-based surfactants and biosurfactants. Partially bio-based surfactants typically


consist of an alkyl chain derived from PKO- or CNO-based fatty acids as a hydrophobic building block which is coupled with a petrochemical- derived hydrophilic building block. For example, fatty alcohol ethoxylates are


typically based on natural fatty alcohols and petrochemical-derived ethylene oxide (EO) despite recent industry initiatives to transform the EO value stream towards biomass on a mass- balanced or even segregated basis. Because of their compatibility, these materials are widely used as weak to moderate foaming co- surfactants, mainly in combination with anionic surfactants, in personal cleansing products such as shampoos, shower gels or liquid soaps. In addition to their use as surfactants, fatty


alcohol ethoxylates serve as raw material for the manufacturing of important anionic surfactants such as alkyl ether sulfates (AES) like sodium laureth sulfate (SLES) or alkyl ether carboxylates. Partially bio-based surfactants are therefore considered as the current standard of the industry because the materials are cheap, biodegradable, insensitive to water hardness and relatively mild to the skin despite their good cleansing and foaming performance. Fully bio-based surfactants are solely based


on renewable feedstocks, which also includes the aforementioned ethoxylates and derivates based on bio-ethylene. Here, the hydrophilic building block is derived from natural feedstocks such as sugars and amino acids, or inorganic molecules like sulfur trioxide. Important examples for fully bio-based


surfactants are alkyl sulfates (AS), alkyl polyglycosides (APG) and amino acid-based surfactants such as glycinates, sarcosinates, taurates and isethionates. These materials are typically more sensitive to water hardness, offer less foaming functionality and are more expensive, compared to partially bio-based surfactants. Interestingly, there are some fully bio-based


surfactants like AS, including Sodium Lauryl Sulfate (SLS) and alpha-olefin sulfonates (AOS), which are harsher and do not offer optimal performance compared to classical SLES. While bio-based surfactants result partially or


fully from renewable raw materials, this does not necessarily translate to a lower carbon footprint compared to petrochemicals. This is somewhat counterintuitive as fossil-based materials – per definition – feature a biogenic carbon uptake of zero. For illustration, cradle-to-gate life cycle


assessment (LCA) studies by Shah et al show natural fatty alcohols based on palm kernel oil may have a higher overall carbon footprint compared to synthetic alcohols due to greenhouse gas emissions associated with deforestation and land-use-changes.2 This example, among others, shows that the industry needs to further broaden the LCA database and understanding to identify and pursue the most sustainable feedstock and value


PERSONAL CARE November 2023 TABLE 1: CLASSES OF BIO-BASED SURFACTANTS


Petrochemical surfactants


Process technology


Feedstocks


Ingredients examples


Alcohol ethoxylates Alkyl ether sulfates


Alcohol ethoxylates Alkyl ether slfates Cocamido propyl betaine


Challenge


Fossil feedstock CO2


footprint


Potential deforestation issue


Not locally sourced Fossil feedstock CO2


footprint


stream options on a scientific basis. To create a coherent understanding, this initiative cannot be limited to personal care but should be based on cooperation between various partners along the value chain and across different industries.


A closer look at biosurfactants Given the ecological challenges with petrochemical-based surfactants and even conventional bio-based surfactants, various researchers in academia and in the industry have been working on alternative solutions. While biosurfactants have been used as


active ingredients within niche applications, they have only recently become more commercialized by various manufacturers, making them more affordable and available in higher volumes. Thus, they are among the latest innovations in a long line of sustainability efforts by the surfactant industry. Unlike their chemically derived


counterparts, these naturally occurring surfactants are produced by fermentation using microorganisms. Interestingly, they are produced as secondary metabolites by a wide range of different organisms, like bacteria, fungi, and yeast, for numerous reasons. Examples include making hydrophobic


substrates more accessible, i.e. digestible, reducing the competition from other organisms through antimicrobial action and/or disrupting biofilm formation by preventing cell adhesion. Because these surfactants are fully derived from locally grown feedstocks such as natural oils and/or sugars, they are a more sustainable product with a lower product carbon footprint compared to classical petrochemical or bio- based surfactants. However, the product carbon footprint of


those materials is clearly dependent on the raw material input as well as energy demand during the fermentation and the subsequent downstream process. Most importantly, the production of these


materials is not associated with the depletion of fossil resources nor biodiversity loss or deforestation issues that are discussed for classically used lauric oils, like PKO, derived from tropical regions. Furthermore, the


Alkyl polyglycoside Sodium Cocoyl glycinate


Potential deforestation issue


Not locally sourced


Sophorolipids Rhamnolipids


Mannosylerythritol lipids


Availability has been


improved as technology moved to production scale


biosurfactant production process offers an exciting opportunity to be incrementally transitioned from using first-generation biomass including vegetable oils and sugars to second-generation biomass such as wood, towards third-generation biomass such as food waste, as a feedstock. However, it is worth noting that there is


consensus within the industry to broaden the LCA database and develop a coherent understanding of the sustainability aspects of these different options.3 From a formulation perspective,


biosurfactants are often not drop-in replacements for traditional, petrochemical- base surfactants, which becomes apparent from their different molecular structure, and might require some new formulation approaches. While state-of-the art formulation concepts have been successfully optimized over decades, these novel ingredients have only recently gained significant focus and attraction by the industry. However, when successfully implemented,


these reformulations may unlock a new realm for personal care products, contributing, for example, to mild cleansing properties, hair conditioning, skin moisturization and more beyond the capabilities of classical ingredients.


Types of biosurfactants and their benefits Among most commercially advanced biosurfactants are glycolipids, including rhamnolipids and sophorolipids, and to a certain extent, mannosylerythritol lipids (MELs). Glycolipids are of particular interest for rinse-off formulations such as hand soap, shampoo, conditioner, mouthwash, make-up removers, anti-acne gels, facial cleansers, and toothpaste. These multifunctional ingredients are mild


to skin and eyes, contribute to cleansing and foaming performance and feature exciting and perceivable skin and scalp care properties. Furthermore, these biosurfactants beneficially affect the human skin microbiome in a variety of ways.1 Rhamnolipids, a subgroup of glycolipids, are


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Partially bio-based surfactants


Fully bio-based surfactants


Biosurfactants


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