Supercritical CO₂-Dried Alginate/Soy Protein Isolate Beads Aerogels for Natural Oil Absorption

Oil spills negatively impact ecosystems and groundwater supplies, harm human and animal welfare, and indirectly contribute to global warming and climate change. Natural oil absorbents, such as aerogels, have gained attention for being low-cost, environmentally friendly, biodegradable, and sustainable. This study synthesized natural oil absorbents from a combination of soy protein isolate and alginate using the sol-gel method. These absorbents underwent surface modification and were then dried using supercritical CO2 at 110 ± 5 bar and 40 °C for 4-5 h to produce alginate/soy protein isolate aerogels. Aerogels are porous solid materials with a huge surface area; thus, their potential as oil absorbents is investigated. The physical characteristics of the oil absorbent are characterized via Fourier transform infrared (FTIR) to identify the interaction of functional groups in the hybrid aerogel, contact angle analysis to evaluate the changes on the surface functionalization characteristics, and oil absorption capacity to measure the ability of aerogel to absorb oil. The composition of the alginate and soy protein isolate was found to influence the hydrophobicity of the aerogels. The alginate/soy protein isolate aerogel with a ratio of 1:1.5 was demonstrated as the optimum formulation of natural oil absorbent with nearly superhydrophobic characteristics with 142.8^o of contact angle and 76% oil absorption capacity.