A comprehensive review of thermal, chemical, and nanotechnology-based wood treatments with industrial applications

Wood is a natural, bio-polymeric material composed primarily of cellulose, hemicelluloses, lignin, and extractives. In ancient times, untreated wood was widely used in construction and furniture making. To improve its durability and stability, it is necessary to modify it due to its vulnerability to physical, mechanical, and biological degradation. Thermal modification, which occurs without chemical agents, aids in dimensional stability and fungal resistance, but qualities such as mechanical strength and susceptibility are sacrificed. Traditional preservatives like chromated copper arsenate (CCA) have been regulated due to the leaching of toxic elements such as arsenic and chromium, which cause health hazards. Alternative waterborne preservatives like alkaline copper quaternary (ACQ) and copper azole (CA) have emerged but often require higher retention levels, making them more expensive and sometimes less effective in leach resistance. New chemical treatments like furfurylation, acetylation, and DMDHEU treatment have shown good durability and stability against fungal decay. Nanotechnology may improve wood penetration, biocide leaching, and ultraviolet (UV) protection. The present comparative review provides an integrated perspective on these modification processes, highlighting their operational principles, treatment efficacy, and commercial viability. As people become more concerned about the environment, new and environmentally friendly wood treatment methods will likely shape the future of preserving wood.