Chemically and Physically Stable Hydrogel Containing Spirulina as a Decarboxylation and an Oxygenation System

Global warming is one of the most serious threats to the global environment ever faced by humans. Therefore, a decarboxylation system is urgently required to help reduce carbon dioxide emmisions and mitigate the effects of global warming. In this study, we demonstrated the potential of a novel glucomannan hydrogel containing Arthrospira platensis (Spirulina) to be both a carbon dioxide absorber and an oxygen generator. The concentration of carbon dioxide in the air-tight space (1.3 L) reduced from 0.72% to 0.07% after 8 h of starting of light irradiation on 10 g of the hydrogel. We combined this hydrogel with phosphorescent pigment, magnetic powder, or inert gas. In a dark space after 10 min light-irradiation using 3.5 g of hydrogel and 30 mL of SOT medium, the amount of dissolved oxygen decreased by 11.2%Sat in the regular hydrogel group and increased by 10.2%Sat in the phosphorescent hydrogel group. Hydrogel containing magnetic powder and that containing inert gas could be easily collected via magnetic adsorption (magnetic separation) and low specific gravity-based separation (floatation separation), respectively. Our findings also demonstrated a useful method for quantification of decarboxylation and oxygenation in a compact space using only small amounts of hydrogel.