Boron fixation effect of quaternary ammonium compounds (QACs) on sodium fluoroborate (NaBF4)-treated wood

Abstract

AbstractAiming at a better leaching resistance of borate-treated wood, the quaternary ammonium compounds (QACs), didecyl dimethyl ammonium chloride (DDAC) and benzalkonium chloride (BAC) were reacted with sodium tetrafluoroborate (NaBF4). The anti-fungal properties of the resulting didecyl dimethyl ammonium tetrafluoroborate (DBF) and benzalkonium tetrafluoroborate (BBF) were tested by the Petri dish method. Poplar (Populus tomentosaCarr.) and Southern pine (Pinusspp.) blocks were treated through a two-step method at three molar ratios of NaBF4to the QACs. The retentions of the reactive components were determined by inductively coupled plasma atomic emission (ICP-AE) spectroscopy and the distribution of boron in wood was observed by scanning electron microscopy/energy-dispersive X-ray analyses (SEM-EDXA). Fourteen-day leaching and water absorption tests were also performed. DBF and BBF both exhibited moderate fungicidal activity againstTrametes versicolorandGloeophyllum trabeumin Petri dishes. The boron remaining in samples after leaching increased with increasing QACs concentration in the second step impregnation. SEM-EDXA showed no obvious morphological changes in the wood surface and DBF and BBF were only found in the cell walls. The water absorption of the treated samples were lower than the controls.