Sustainable Technology Finalist: Cosmetic Silica Upcycled from Rice Husk as Natural Alternative to Microplastic Powders - Tech Briefs

“The personal care market is seeking innovative cosmetic ingredients that feature high sustainability profiles, excellent optical and sensory properties, and adhere to regulatory standards,” said Dow Silicones Belgium SRL’s Anne-Marie Vincent. Her project focuses on commercializing silica upcycled from rice husk to address these needs.

Current regulations limit the use of several cosmetic powders in cosmetic products due to their classification as microplastics, so there was a need to develop an alternative powder that could replace those cosmetic powders. The EcoSmooth™ Rice Husk Cosmetic Powder is a silica from rice husk waste origin that can offer similar optical and sensorial performance than Polymethylmethacrylate (PMMA) powder and Nylon-12 powder.

Contrary to PMMA and Nylon-12, this material can be dispersed in the water or the oil phase of the cosmetic emulsions, and therefore, performs well in a wide variety of skin care (cream), color cosmetic (foundation), and hair care (dry shampoo) formulations.

“Several silica materials derived from rice husk, with varying particle sizes and surface areas, were analyzed to identify the most promising candidate. This analysis was guided by a fundamental understanding of the material structure-property relationship in skin care formulations, aiming for optical benefits and skin-blurring effects,” said Vincent.

This new silica is efficient at low use level (1.5 percent) to offer immediate skin imperfections masking together with a smooth sensory profile on the skin. It is also addressing the beauty care certifications required for cosmetic raw material such as Cosmos approved, non-Genetically Modified Organism (GMO) and 100 percent natural origin as per ISO 16128 standard.

This amorphous silica is easy to produce at the manufacturing scale as it is produced via similar process than conventional silica. The distinctness of this raw material is its upcycling process, which is transforming waste from rice ash into new materials or products perceived to be of higher value.

The EcoSmooth™ Rice husk Cosmetic Powder with a particle size about 4 to 7 microns and a surface area ranging from 500 to 700 g/m2 was commercialized in 2022. Its optical and sensorial performances were evaluated and compared to PMMA and Nylon-12 powders using an oil-in-water skin care formulation chassis:

In vitro measures of total light transmission and haze for skin care formulations containing 1.5 percent of the silica (dispersed either in the oil phase or in the water phase) were carried out. The haze value for both formulations was around 80. This high haze value translates into a high probability for in vivo skin imperfections masking. The haze value for the PMMA and Nylon-12 powders were slightly lower than for silica. Both powders could not be homogeneously dispersed in the water phase and could not be measured.

The sensory of the oil-in-water formulation containing 1.5 percent of the rice husk silica was compared in vivo by 18 panelists. Similar smoothness and slipperiness were found for the three powders. The formulation with the silica compared to the Nylon-12 was found slightly less greasy and left less film residue on the skin.

Because of its sebum/oil absorption benefit, it can also absorb skin sebum from panelist forehead and decrease the undesired skin shine over time.

The EcoSmooth™ Rice Husk Cosmetic Powder was launched in 2022 worldwide. This broad campaign resulted in several hundreds of customers samples requests, according to Vincent, which is a sign of significant customers interest for this raw material. Actual commercial sales started in 2023 and are now developing in 2024.

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This article first appeared in the November, 2024 issue of Tech Briefs Magazine (Vol. 48 No. 11).