Copper leaching performance of ACQ-D treated wood after medium hot air post-treatments

Chinese fir (Cunninghamia lanceolata Hook.) wood cubes (19x19x19 mm) treated with alkaline copper quat-type D (ACQ-D) solution were conditioned at hot air post-treatments with medium temperatures (50 and 70 degrees C), different vacuum degrees (atmosphere: 0.02, 0.04, 0.085 MPa) and air velocities (0, 0.5, 1, 2.5 m.s(-1)) to evaluate the effects of oxygen concentration and air velocity on copper leaching of ACQ-D treated wood after medium hot air post-treatments. The results showed that the lower oxygen concentration during post-treatments caused by the higher vacuum degree would hinder the copper fixation and result in more copper loss from ACQ-D treated wood. While at atmosphere pressure, a high air velocity has both positive and negative effects on copper leaching. At lower temperature of 50 degrees C, the adverse effect exceeds the positive effect, which causes an increase in copper leaching after post-treatments with air circulation compared with post-treatments without air circulation. But at higher temperature of 70 degrees C, the copper leaching resistance performed the best at an air velocity of 0.5 m.s(-1).