Valorization of Sugarcane By-Products through Synthesis of Biogenic Amorphous Silica Microspheres for Sustainable Cosmetics
Joana R. Costa, Ana Paula Capêto, Carla F. Pereira, Sílvia Santos Pedrosa, Inês F. Mota, João da Silva Burgal, Ana I.E. Pintado, Manuela Pintado, Catarina S. Oliveira, Patrícia Costa, Ana Raquel Madureira
Abstract
Ashes from sugarcane by-product incineration were used to synthesize silica powders through alkaline hot extraction, followed by ethanol/acid precipitation or the sol-gel method. Both production methods allowed amorphous spherical silica microparticles with sizes ranging from 1-15 μm and 97% purity to be obtained. Water absorption ranged from 135-155 mL/100 g and 150-250 mL/100 g for precipitated silica and silica gel, respectively, while oil absorption ranged from 305 to 390 and from 250 to 350 mL/100 g. The precipitation with ethanol allowed the recovery of 178 g silica/kg ash, with a lab process cost of EUR 28.95/kg, while the sol-gel process showed a yield of 198 g silica/kg ash with a cost of EUR 10.89/kg. The experimental data suggest that ash from sugarcane by-products is a promising source to be converted into a competitive value-added product, minimizing the environmental impact of disposal problems.