Application of magnetite supplementation for enhancing biohydrogen production using Gelidium amansii hydrolysate

Acid hydrolysis of biomass generates a high concentration of hydrolysis by-products, which must be removed. Magnetite (Fe₃O₄) supplementation can reduce the amount of powdered activated carbon (PAC) input required for detoxification by increasing hydrogen productivity and alleviating the inhibitory effects of hydrolysis by-products. In this study, sugars were extracted by acid hydrolysis of Gelidium amansii, and hydrogen production using this was quantified with the magnetite supplementation. The total sugar concentration of 0.5 % H₂SO₄ hydrolysate was 24.4 g/L, including 3.7 g/L of glucose, 18.9 g/L galactose, and 1.7 g/L of arabinose, as well as hydrolysis by-products of 0.9 g/L of formic acid, 1.2 g/L of levulinic acid, and 11.4 g/L of 5-hydroxymethylfurfural (5-HMF). Magnetite supplementation at a concentration of 1.3 g/L or less in 5-HMF, the main by-product, increased hydrogen production by an average of 11.4 %. This strategy will optimize future biohydrogen production processes using Gelidium amansii and reduce detoxification costs.