Processing wheat straw into a near-infrared light selective transmission film

Abstract

This research focuses on the development of near-infrared light selective transmission film (NIR-LSTF) utilizing wheat straw biomass, extracting lignocellulose and lignin through the acetic acid method. Employing a hydrogel-based approach, lignin was encapsulated and underwent self-assembly both within and atop the hydrogel, enabling initial integration with cellulose. Hot pressing facilitated the thorough amalgamation of lignin into the cellulose matrix, enhancing the NIR-LSTF's resistance to environmental wear and creating a dense structure that minimizes light loss and reflection, thus outperforming traditional materials in optical efficiency and functionality. Moreover, the presence of lignin imparts the material with unique selective absorption characteristics, effectively blocking nearly all ultraviolet light and visible light (approximately 100 % at 610 nm and 78 % at 780 nm), while maintaining a high transmittance rate (∼90 %) in the near-infrared spectrum. This property underscores the films' significant potential in applications demanding near-infrared transparency. The efficacy of NIR-LSTF in the realms of infrared surveillance and privacy protection was assessed, yielding favorable experimental outcomes. This study paves a new pathway for the valorization of agricultural waste biomass within the near-infrared optical domain.