Effect of Wood-drying Condensate on Emission of Volatile Organic Compounds and Bonding Properties of Fibreboard

Abstract

Potential use of condensate generated by cooling the steam obtained during high-frequency/vacuum drying step of hardwood lumber was investigated. The liquid condensates were obtained from oak, beech and walnut wood. This liquid condensate was then used as a replacement for deionized water in the synthesis of Urea-Formaldehyde (UF) resin (5 wt% of total resin) using a laboratory scale reactor. Medium Density Fibreboards (MDFs) were produced using control and modified resins. Emissions of Volatile Organic Compounds (VOCs) from the MDFs were determined by Mcro Chamber method. The bonding properties of the MDFs were determined according to European standards. The main VOC emissions from MDFs produced using UF resin containing the condensate were a-Pinene, b-Pinene, careen, and acetic acid, which were lower than those of the control MDF, except for the acetic acid emission of MDF with oak condensate. In the tree species, the beech wood condensate gave the lowest VOC emissions (732 μgm-3) from the MDFs, followed by the MDFs containing walnut wood condensate (852 μg·m3), oak wood condensate (998 ugnf3), and control MDF (3529 μg-3), respectively. However, the internal bond strength of MDFs containing the condensate was negatively impacted by the condensate (0.70 N·mnf-2 to 0.54 N·mm-2 depending on the tree species). The results showed that the liquid wood-drying condensate which generally released to the ground could be efficiently used as an alternative to expensive VOCs scavenger used in the production of UF resin bonded MDF. This may be one of the most efficient uses of the condensate in high value-added materials.