A green delignification and enhanced fire-retardancy of corn husks for fire-safety applications

The world is focusing on developing environmentally friendly methods due to rising pollution levels, necessitating the usage of sustainable materials. Corn husk, an agricultural waste, can be a potential candidate for green composite materials. This study employs a green approach to delignify the raw corn husk (RCH), yielding a delignified corn husk (DCH) with a rough and opened micro/nanoporous structure. Furthermore, in-situ mineralization of hydroxyapatite (HAP) and coating with a nanoclay/MgSO4 (NC/M) solution developed a flame-retardant corn husk (FRCH). The FRCH was thoroughly characterized using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), limiting oxygen index (LOI), and cone calorimetry (CC) to ensure the successful preparation of FRCH and its enhanced flameretardancy. FRCH demonstrated excellent flame retardancy, withstanding a butane-based open flame for over 60 s without igniting. In contrast, RCH combusted completely within 3 s under the same conditions. TGA results further validated the thermal stability of FRCH, indicating a residual mass of 46.1 % at 600 degrees C, significantly higher than that of RCH (22.9 %) and DCH (14.9 %). Cone calorimetry analysis indicated a peak heat release rate (pkHRR) of 27 kW/m2, total heat release (THR) of 1.6 MJ/m2, and total smoke release (TSR) of 6.8 m2/m2, exhibiting a superior flame-retardant performance of FRCH compared to other lignocellulosic materials. The developed FRCH is a potential candidate for its diverse applications in various sectors particularly in lithium-ion batteries (LIBs), for enhancing fire safety in electric vehicles (EVs).