Cuttlebone-inspired magnesium oxychloride cement reinforced by biochar as green adhesive for wood industry

Design of eco-friendly, non-formaldehyde and flame retardant wood adhesives is in high demand for the wood industry, which can help to alleviate environmental stress and human health concerns. Magnesium oxychloride cement (MOC) can reduce CO 2 emission and increase the value-added utilization of potash industry wastes, making it an ideal alternative to hazardous formaldehyde-based adhesives. However, its practical application usually suffers from poor water resistance and the filtering effect of wood. Inspired by the porous structure of cuttlebone, a facile yet powerful strategy is presented to prepare MOC adhesive with outstanding water resistance, compressive strength and adhesive ability to wood through introducing biochar. The naturally porous structure of biochar can form a protective core-shell structure and encapsulation with hydration products to stabilize phase 5 (5Mg(OH) 2 ·MgCl 2 ·8H 2 O), avoid crack extension and mitigate the filtering effect of wood. Meanwhile, the abundant functional groups of biochar can construct multiple interactions with Mg 2+ , which contributes to forming an internal network with excellent cohesion strength . Compared with pristine MOC, the obtained MOC/Biochar exhibited 102.33%, 32.33% and 31.45% increases in water resistance, compressive strength and wet adhesion strength, respectively. This work provides a promising strategy in preparing eco-friendly MOC-based adhesive from agricultural and industrial by-products to reduce environmental hazards. • An eco-friendly, flame retardant and non-formaldehyde wood adhesive was proposed. • Biochar was used to form multiple interactions in magnesium oxychloride cement. • The composite showed integrated water resistance and compressive strength. • Adhesive alleviated the filtering effect of wood and showed good adhesion strength.