Study On Wood Color Regulation Technology Of Robinia Psoudoacacia Based On Coordination Reaction

The color of wood is one of the important indicators to evaluate the quality and utilization value of wood.To solve the problem of high-value utilization of Robinia psoudoacacia wood resources and to alleviate the imbalance of the current market supply and demand relationship of Pterocarpus macarocarpus kurz wood resource,in this study,a new idea and method for adjusting the chromophore structure of the Robinia pseudoacacia were selected.The Robinia pseudoacacia was selected as the coloring treatment material,and the heartwood of Pterocarpus macarocarpus kurz was the coloring target material.Based on the metal complex theory,the chromophore structure of the Robinia pseudoacacia was adjusted and modified to make its color tend to the target material,namely the heartwood of Pterocarpus macarocarpus kurz;By characterizing the color system structure before and after the treatment,the coloring mechanism was preliminary revealed;By changing the relevant process conditions,the color change law of Robinia pseudoacacia was analyze under different technological conditions:The most suitable technological conditions for actual production and the color closest to the target material was choosed.The main conclusions are as follows(1)Compared with Robinia pseudoacacia,Pterocarpus macarocarpus kurz chromophore system has higher coloring substance content,higher conjugated carbonyl content,higher degree of condensation,and higher degree of conjugation with benzene ring.Among the lignin,the guaiacyl G and p-hydroxyphenyl H structural units account for a relatively high proportion.Pterocarpus macarocarpus kurz has higher polymerization degree of lignin and larger molecular weight;the content of colored substances in the extract is higher,which has a significant effect on color.The lignin of Robinia pseudoacacia is mainly composed of syringyl S and guaiacyl G structural units,with more methoxy structure,resulting in a lower degree of polymerization and a lower molecular weight of lignin;the extract component has no significant effect on its color,as well as its conjugated system is smaller(2)After treatment with different metal ions,the color of Robinia pseudoacacia changed to different degrees.Among them,after Fe(?)ion treatment,the wood of Robinia pseudoacacia showed the reddish-brown color,which is similar to that of Pterocarpus macarocarpus kurz.Introducing ammonium acetate and Fe(?)ion to treat the Robinia pseudoacacia wood powder,the color is closer to the target material(3)After Fe(?)ion treatment,the degree of conjugation of the color system increases and the content of conjugated carbonyl groups increases.The non-conjugated carbonyl groups in Robinia pseudoacacia are the main functional groups participating in the reaction.Introducing ligand ammonium acetate with Fe(?)ion to treat Robinia pseudoacacia wood resulted in a further increase in the absorption coefficient of Robinia pseudoacacia in the visible region.The "wood-Fe(?)ion-ligand",complex and the formation of iron oxide together led to the red-brown color change of Robinia pseudoacacia after treatment with ammonium acetate and ferric chloride mixed reagent.(4)In order to make the Robinia pseudoacacia wood tend to be the target material the heartwood of Pterocarpus macarocarpus kurz,the optimal coloring process is a mixed aqueous solution of FeCl3 and ammonium acetate with a concentration of 0.08 mol/L of 1:1 and a constant temperature water bath at 100?,which was treated under the conditions for 3 hours.The treated wood was then dried at room temperature until the moisture content was 10%-12%.The color difference ?E*of Robinia pseudoacacia wood sapwood and Pterocarpus macarocarpus kurz after treatment with this process condition was 5.44,and the color difference ?E*of Robinia pseudoacacia heartwood and Pterocarpus macarocarpus kurz was 4.48.