Construction of layered double hydroxides on wood surfaces for wood coloring

Wood dyeing usually requires a large concentration of metal solution, which when released to the atmosphere as waste liquid, causes pollution. In this study, a metal-organic framework (MOF) with micron-size structure was in -situ grown on a wood surface as a template and precursor for a layered double hydroxide (LDH). The LDH had a nanoscale structure and was generated on the wood surface from ultra-low concentration NiCl2 solution. The generation was based on a hydrolytically induced exchange process between the MOF and hydroxide ions. The results of following this procedure showed that petal-like Co/Ni-LDH with micro-nano composite structure was formed on the wood surface. Due to the LDH, a uniform light green color was formed on the wood surface at a reaction temperature and time of 60 celcius in 34 min, respectively. To improve the hydrophobicity of the LDH layer, a long chain alkyl with low surface energy was introduced into the lamellae from a sodium stearate solution, constructing a superhydrophobic layer on the wood surface. The modified wood surface showed excellent UV light aging and water resistances. Moreover, Ni2+ was replaced with Mn2+, Fe3+, Cu2+, and Zn2+ ions and dark brown, yellow, blue, and white colors, respectively, were formed on wood. The present method is also suitable for other wood. Wood surface color adjusted by LDH uses low concentration of metal salt solution and proved to be a mild and green wood color toning method.

Automated summary

In this study, a metal-organic framework (MOF) was grown on a wood surface to generate a nanoscale layered double hydroxide (LDH) for wood dyeing. The LDH formation was achieved through a hydrolytically induced exchange process between the MOF and hydroxide ions. The modified wood surface exhibited a uniform light green color and excellent UV light aging and water resistances. This method is mild, environmentally friendly, and can be applied to other types of wood.