Effect of oxalic acid pretreatment of wood chips on manufacturing medium-density fiberboard

The main objective of this study was to evaluate the effect of oxalic acid (OA) wood chips pretreatment prior to refining, which is done to reduce energy used during the refining process. Selected mechanical and physical performances of medium-density fiberboard (MDF) - internal bonding (IB), modulus of elasticity (MOE), modulus of rupture (MOR), water absorption (WA) and thickness swelling (TS) - made from this OA-pretreated wood were tested and the effect of the OA treatment on carbohydrates investigated. The results showed that the OA treatment significantly reduced refining energy usage, and improved MDF dimensional stability and lightness. However, the OA treatment had a negative effect on the internal bonding strength of MDF panels. The amount of extracted carbohydrates was dramatically increased, up to 24 times, by the OA pretreatment. Carbohydrates extracted from wood chips could be a potential sustainable resource for biofuel or bio-based chemicals. This paper is a contribution to the so-called "value prior to pulping (VPP)" concept.