Efficient H2O2-system for fiber delignification-bleaching and its environmental impact

Hydrogen peroxide (H2O2) is considered an eco-friendly oxidizing agent because it can decompose into water and oxygen in water. H2O2 has been implemented in the lignocellulosic delignification-bleaching through lignin degradation or dye by reactive radical species, improving cellulose yield, changing fiber properties, and enhancing the whiteness index. However, the conventional process requires high temperatures and extended durations, which risk fiber damage, high energy consumption, and economic losses. To improve the efficiency and effectiveness of the H2O2, fiber processing systems can be combined using alkaline-peroxide, microwave-assisted, photocatalyzed with ultraviolet (UV) irradiation, tetraacetyl ethylenediamine (TAED)-activated, complex metal-catalyzed (e.g., Mn, Cu, and Fe), TBBC and TBCC-activated, glycerol triacetate, acetylated starch, and other combinations (e.g., tetraacetylhydrazine, potassium persulfate, sucrose octaacetate, cyanamide, liquid ammonia, or manganese acetate). This article presents the route and mechanisms for improving the H2O2 oxidation performance in fiber fabrication processes. The impact of H2O2 discharge into the environment and future challenges are also discussed for sustainable and responsible manufacturing. In conclusion, improved H2O2 systems in fiber delignification-bleaching have higher performance effectiveness and efficiency than conventional methods. However, the disposal of residual H2O2 to the environment requires attention. Graphical abstract