Lignocellulose-Based Optical Biofilter with High Near-Infrared Transmittance via Lignin Capturing-Fusing Approach.

Near-infrared (NIR) transparent optical filters show great promise in night vision and receiving windows. However, NIR optical filters are generally prepared by laborious, environmentally unfriendly processes that involve metal oxides or petroleum-based polymers. We propose a lignin capturing-fusing approach to manufacturing optical biofilters based on molecular collaboration between lignin and cellulose from waste agricultural biomass. In this process, lignin is captured via self-assembly in a cellulose network; then, the lignin is fused to fill gaps and hold the cellulose fibers tightly. The resulting optical biofilter featured a dense structure and smooth surface with NIR transmittance of ~90%, ultralow haze of close to 0%, strong ultraviolet-visible light blocking (~100% at 400 nm and 57.58% to 98.59% at 550 nm). Further, the optical biofilter has comprehensive stability, including water stability, solvent stability, thermal stability, and environmental stability. Because of its unique properties, the optical biofilter demonstrates potential applications in the NIR region, such as an NIR-transmitting window, NIR night vision, and privacy protection. These applications represent a promising route to produce NIR transparent optical filters starting from lignocellulose biomass waste.

Fabrication of lignin-containing cellulose bio-composite based on unbleached corncob and wheat straw pulp.

In contemporary life, plastic, a kind of petroleum carbon source, has been produced and used in varieties of applications. However, the vast consumption of petroleum-based plastic and the burning of agricultural wastes make the environmental problems increasingly severe. Furthermore, a large number of lignocellulosic resources (such as corncob and wheat straw) are often wasted and burned, which will aggravate the environmental damage. In this paper, we use unbleached corncob and wheat straw pulp to fabricate the lignin-containing cellulose bio-composites (LCBs) to reduce non-renewable energy consumption and utilize agricultural wastes. The LCBs were obtained by a direct manufacturing process in benzyltrimethyl ammonium hydroxide (BzMe3NOH) aqueous solution under mild conditions, constituting an entwined composite structure of cellulose micro/nano-fibers. This unique micro/nano-structure provides bio-composites with the outstanding mechanical performance of 96.7 MPa and a high haze of 90.1%. Meanwhile, with the inherent lignin, the LCBs could filter over 81.8% UV-C. As the raw material used is pure natural lignocellulose, the bio-composites prepared have innate environmental friendliness. With exceptional mechanical strength, UV-shielding property, and innate environmental friendliness, the LCBs are possible and potential substitutes for traditional petroleum-based plastic that is easily aging or non-biodegradable.

Facile one-step fabrication of all cellulose composites with unique optical performance from wood and bamboo pulp.

Cellulosic substrates completely originating from biomass have gained increasing attention for utilization in photoelectric devices due to their biodegradability, sustainability, and renewability. Herein, a simple one-step strategy was used to fabricate transparent (84.2%-90% at 550 nm) all-cellulose composites (ACCs) with customized optical haze (14.7%-83.7% at 550 nm) from wood and bamboo pulp due to their variable solubility. Surface roughness, coagulation bath composition, and the size of the undissolved cellulose fibers contributed to optical haze regulation. Fabricated ACCs demonstrated water resistance, thermal stability, and good mechanical properties. Moreover, an enhancement in the power conversion efficiency of a perovskite solar cell was achieved by simple attachment. Compared with non-sustainable petroleum base materials, ACCs exhibit biodegradability and renewability, which makes the composites promising in large-scale production and various applications due to their tunable haze.