Environmentally Benign Wood Modifications: A Review

Wood modification, an efficient approach to enhance the intrinsic properties of wood, has been extensively studied for decades. Due to growing environmental awareness, the sustainability of wood modification has received more attention. Generally, the sustainability in wood modification should consist of three aspects: an environmentally friendly processes, renewable modifying agents, and nontoxic and biodegradable resultant products. Recently, some biobased modifying agents obtained from renewable feedstocks were explored for substituting the petroleum-based ones. This review focuses on representative wood modification methods, including furfurylation, impregnation with natural products and biodegradable polymers, and chemical modification with sustainable reagents, since these methods have the potential to enhance wood properties. However, there are many challenges for using these agents, including effectiveness in penetration, evenness in distribution, and durability. The cost, process conditions, and equipment of these methods could also be challenges for scaling up. In addition, current studies mainly pay attention to the green reagent selection and property enhancement, rather than environment behavior evaluation of the resultant products. Effort should be made to evaluate the ecotoxicity and degradation behavior of the modified wood since it can help us determine whether the new formulations are sustainable. Much work needs to be done to overcome the obstacles above-mentioned and to develop efficient modification methods with a minimum environmental impact.