Study On Mechanism Of Carbonization For Thinning Wood Of Chinese Fir And Application Of Its Carbonized Materials In Environmental Protection

In the past, mainly used as a fuel, wood-based carbonized materials don't see much service in other fields, and researches on wood-based carbonized materials were not attached much importance to. In recent years, as science and technology has been developing rapidly, researches and development on the use of wood-based carbonized materials as a new material are more and more widespread. To develop and utilize wood-based carbonized materials in an efficient way will play a positive role in waste resource recycling, environmental protection, ecology and so on. With the renewal of advanced instruments and means, it is necessary that breakthroughs be made in researches on wood-based carbonized materials. This paper attempts to do some researches on mechanism of carbonization and application of carbonized materials in environmental protection by using thinning wood of Chinese fir as raw materials, one of the rapidly growing trees in Southern area of China.(1) By techniques of one-step and two-step carbonization, capped and uncapped carbonization, with carbon dioxide, nitrogen, oxygen, air and their mixture as atmosphere gas, the experiments on Chinese fir thinnings are carried out, with special focus on the basic pyrolysis process of its saw dust and the affecting laws on carbonized materials under different carbonization conditions.(2) By means of TG and DSC analyses, variation laws of samples' weight and heat are analyzed when the carbonization temperature is continuously rising, and relevant thermodynamics parameter is obtained, which provides theoretical basis for carbonization temperature and heating rate.(3) By means of element analysis, variation laws of carbon, hydrogen, oxygen content and main functional group are analyzed in the process of carbonization. With Raman, XRD, XPS and other analytical methods, researches and characterization on chemical structure ofcarbonized material, surface functional group and microcrystal structure are conducted, which indicate its evolution laws and developing features.(4) By means of SEM, HRTEM, automated specific surface area and pore size analyzers, micro-structure of carbonized material, crystallization state, pore size distribution, as well as specific surface area and characteristics of pores are observed and analyzed, with emphasis on formation of micropore, development laws and variation laws among inner atom crystal. Nanophase carbon tube, onion-like graphitic particles and diamond structure are first found in wood charcoal of Chinese Fir.(5) The experiments reveal the critical temperature point where the qualitative change of carbonized material occurs.(6) Absorptive effect of carbonized material on VOC pollutants as well as effect of carbonization temperature on adsorptive properties are studied.(7) Oil-absorptive material from Chinese fir thinnings are developed and its absorptive effects are also studied.