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.

In the last decade, selectively tuned bio-based polyesters have been increasingly used for their clinical potential in several biomedical applications, such as tissue engineering, wound healing, and drug delivery. With a biomedical application in mind, a flexible polyester was produced by melt polycondensation using the microbial oil residue collected after the distillation of β-farnesene (FDR) produced industrially by genetically modified yeast, Saccharomyces cerevisiae. After characterization, the polyester exhibited elongation up to 150% and presented Tg of −51.2 °C and Tm of 169.8 °C. In vitro degradation revealed a mass loss of about 87% after storage in PBS solution for 11 weeks under accelerated conditions (40 °C, RH = 75%). The water contact angle revealed a hydrophilic character, and biocompatibility with skin cells was demonstrated. 3D and 2D scaffolds were produced by salt-leaching, and a controlled release study at 30 °C was performed with Rhodamine B base (RBB, 3D) and curcumin (CRC, 2D), showing a diffusion-controlled mechanism with about 29.3% of RBB released after 48 h and 50.4% of CRC after 7 h. This polymer offers a sustainable and eco-friendly alternative for the potential use of the controlled release of active principles for wound dressing applications.

There is a great interest in replacing conventional fossil-based polymers and composites with inorganic or organic waste-based materials and filler-type additives, to promote environmental sustainability and circularity. The main objective of this study was the design of water-blown polyurethane rigid foams integrating two by-products derived from the Amyris fermentation process of production of β-farnesene. The distillation residue (FDR) was used as main polyol component in the neat formulation of the foams (PF) that it was supplemented (PFA) with 4.5% of sugarcane bagasse ash (SCBA) added as a filler with fire-retardant properties. The impact of both by-products on the foam density and morphology, and in the thermal, mechanical, and flame-retardant properties was assessed. SCBA presence led to a reduction in apparent density, cells size, and glass transition, delaying the thermal decomposition. The differences observed in the thermal conductivity and flammability test parameters suggest a visible impact of the ash incorporation, thus meeting the fire protection standard UL 94, class HB. Highlighting the need for further optimization, this work presents a practical example of the integration of different wastes derived from the same fermentation process in the formulation of sustainable PUR foams with reduced flammability.