High Captured Carbon Content Bioplastic Film from Spirulina

Abstract

Bioplastics offer a solution to the problem of increasing atmospheric CO₂ levels contributed by the linear production and consumption pattern of fossil-derived plastics by closing the carbon loop with material sourcing from biomass and bioplastic's biodegradability. Spirulina, a genus of cyanobacteria that is capable of rapid CO₂ uptake, can be the key to realizing a circular plastic economy by converting atmospheric CO₂ to value-added high protein content biomass, from which the protein can be extracted and processed to produce protein-based bioplastics with high captured carbon content that is biodegradable, releasing CO₂ after decomposition to be returned to the cycle. To demonstrate the feasibility of utilizing the self-assembling capabilities of Spirulina protein to fabricate bioplastics, a simple procedure is proposed that involves protein isoelectric point precipitation followed by solvent casting to produce an entirely Spirulina protein-based bioplastic film containing glycerol as the plasticizer without blending with other types of conventional plastics. By further crosslinking with carboxymethylcellulose and Ca²⁺ cations, are able to obtain films with the highest average tensile strength of 5.5MPa. Additionally, the Spirulina protein films showed potential in UV-blocking applications and exhibited good biodegradability.