Research On Adsorption And Fixation Of ACQ-C In Wood Based On Fractal Theory

Wood preservation is a common method to improve the performance and increase the added value of wood.However,the wood preservation process has always depended on experience and lacked theoretical guidance.The paper takes poplar and Chinese fir as the research object,and based on the principle of fractal and the principle of wood infiltration,the adsorption and fixation of water-borne preservatives in wood are studied.Wood was firstly treated by impregnation at normal pressure and temperature,vacuum impregnation and vacuum pressure impregnation separately.Study the permeation mechanism of wood in air-dry,dry-out,and vacuum freeze-dried.Analytical instruments such as FTIR,ICP-OES,and SEM were used to characterize the changes in the functional groups before and after the treatment,the content of effective elements,and the surface characteristics to clarify the fixation and adsorption of ACQ-C in the wood.Wood were pretreated by NaOH,ethanol extraction,active enzyme treatment,heat treatment and microwave treatment separately,and the effects of different pretreatment methods on drug absorption and loss resistance of wood were studied.The paper studied the main chemical constituents of wood:cellulose,hemicellulose,and lignin in the penetration and adsorption of ACQ-C.Using the image processing function of Matlab,the grayscale image of wood is processed with black and white binarization,and the image is counted by the box dimension method to measure the box dimension of the wood.Based on the Darcy theorem and the Poiseuille theorem,the relationship between the fractal dimension of wood pores and permeability was established.The paper proposes a new research method for wood modification theoretically,which breaks through the limitations of the traditional linear regression method to study the relevant properties of wood.The results can be used to improve the formulation of wood preservatives and the wood modification process and has theoretical guiding significance for the development of wood industry.The innovation of the thesis lies in the application of the fractal theory to the field of wood preservation.Based on the fractal principle and the wood penetration mechanism,the optimization of wood structure and modification process parameters were integrated to obtain a fractal model of ACQ-C penetration and fixation in wood pores.Fractal calculation of the pore structure of wood is used to determine the optimal infusion technological conditions for wood,thereby solving the key technical problems that prevent the quality of wood from being difficult to control,changing the traditional empirical process research practices,and providing new ideas for wood improvement.This paper drew the following conclusions:(1)Wood species and impregnation technology have a significant effect on the amount of ACQ-C absorbed in wood.The volumetric inhalation amount of Chinese fir and poplar at atmospheric pressure is equivalent.The volumetric inhalation doses of the softwood Chinese fir by vacuum and vacuum pressure method increased by 33%and 131%,respectively,compared with the normal pressure method.The volumetric inhalation doses of the broadleaved poplar by vacuum and vacuum pressure method increased by 62%and128%,respectively,compared with the normal pressure method.(2)In the process of impregnation at atmospheric pressure,the effect of drying method on the amount of inhalation was significant,and the impact on poplar was greater than that on Chinese fir.The amount of wood absorbed was the largest after vacuum freeze-drying,followed by atmospheric drying,and conventional high-temperature drying is minimal.The fixation of copper ions in wood was related to the moisture content of wood,which indicated that the fixation capacity of copper ions would be increased after Vacuum freeze-drying.After freeze-drying,the fixation amount of copper ions in poplar was 13.7%higher than that of air-dried ones,while that of Chinese fir was 13.2%higher.(3)The volumetric inhalation amount of poplar was increased by 21.3%,11.0%,65.0%and 16.0%,respectively,compared to untreated wood after NaOH,ethanol extraction,microwave pretreatment and enzyme treatment;while the increase in Chinese fir was increased.7.5%,19.0%,69.0%,and 15.0%.(4)the fixation rate of copper ions was significantly increased after pretreatment,in which the fixation ratio of poplar and Chinese fir were increased by 10.67%and 14.99%respectively after microwave pretreatment.After ethanol extraction,the fixation rates of poplar and Chinese fir were improved by 5.88%and 0.62%,respectively.After heat treatment,the fixation ratios of poplar and Chinese fir were increased by 6.31%and 0.89%,respectively.The leaching resistance of the specimens deteriorated significantly after NaOH pretreatment.The fixation ratios of poplar and Chinese fir were decreased by approximately17.83%and 34.07%respectively.The immobilization rates of poplar and Chinese fir after enzyme treatment were decreased by 19.87%and 16.30%respectively.(5)The method of calculating the fractal dimension of box-counting was used to calculate that the fractal dimension of poplar and Chinese fir was 1.7598~1.8841 and1.8499~1.8941 respectively.According to the Darcy's law and Poiseuille's law,the relationship between the wood fractal dimension D and the permeability K,(?),was established.(6)In this experiment,the relationship between the volume absorption of wood and the independent variables of various factors is more in line with the linear relationship.The adsorption equation of poplar is:A_y=0.1793K+0.2848P+0.5719T-0.2645C+0.0779.The adsorption equation of Chinese fir is:A_s=-0.1396K+0.6248P+0.6036T-0.0088C+0.0711.The predicted values were in good agreement with the actual test values.