Color adjustment of black locust (Robinia pseudoacacia L.) wood by producing chromogenic structure under heat treatment

Abstract

To improve the appearance of the black locust wood under heat treatment, ammonia (AM), acetic acid (AA), and ammonium acetate (AMA) were adsorbed into the black locust wood flour, with or without aluminum sulfate octadecahydrate (ASO). The color parameters (CIE L*a*b*) of the black locust wood flour treated with different conditions were measured. Diffuse reflectance ultraviolet-visible spectroscopy (DRUV-Vis) and the attenuated total reflection/Fourier transform infrared spectroscopy (ATR-FTIR) were conducted to reveal the changes of the chromophore systems. X-ray photoelectron spectroscopy (XPS) was used to demonstrate the extreme valence of the atomic content and the occurrence of a coordination reaction. The color of the wood flour became reddish after the treatment with AMA+ASO. There was an increase in carbonyl structure and carboxyl structure of the wood flour treated with AMA and ASO.