Scaling Up Synthesis of Biomass Microbeads and Analyzing Their Rheological Effects in Consumer Products
Commercially, microbeads are used in large quantities in personal care products ranging from soaps to toothpastes. Microbeads are used to increase their viscosity and abrasiveness, but they flow into wastewater streams after use and eventually pollute the ocean. To combat this, biodegradable microbeads can be synthesized from unmodified cellulose using an emulsion-precipitation approach. For practical use in industry as a replacement to their non-biodegradable counterparts, the effects of reaction scale-up must be analyzed, so an emulsion at five-fold scale was performed. Based on sieving analysis, 17.2% of beads recovered yielded diameters of less than 850μm–the desired size of the beads. With scanning electron microscopy, the morphology of the beads were found to be rougher and less spherical compared to the cellulose microbeads synthesized on the small scale. To analyze their use as rheological modifiers, the beads produced from this scaled-up emulsion were added to a model hand cream of 20:40:40::Span80:water:sunflower oil at a weight fraction of 2% and the suspension was sheared on a rheometer to measure the viscosity. Compared to the pure model hand cream, the viscosity over a range of strain rates was higher for the model cream containing the beads by approximately a factor of three-fold, a promising sign for the performance of these beads in consumer products. Based on the results of this initial scale-up and rheological analysis, reaction parameters, such as geometry, temperature, and bead composition, can be fine-tuned to optimize yield and rheological properties.