Terahertz Time-domain Spectroscopy Study Of Montmorillonite

Clay mineral,one of the most abundant minerals in geology,is a key composition of soil,conglomerate,sediments and so on.Being a kind of natural Nano-micro material,the clay mineral is also playing an important role in application of various industries,such as oil and gas resource searching,geological evolution exploring and biochemical engineering.The traditional mineral characterization methods often have their own limitations,so providing a new type of detection method will facilitate the study of minerals in a more profound and comprehensive way.As a new type of spectral detection technology,the terahertz time-domain spectroscopy technology can perform non-destructive detection of minerals due to many advantages of long wavelength,low photon energy,and high spectral resolution,etc.,in the meanwhile to distinguish the changes of crystal structure.This thesis focuses on the using of terahertz time-domain spectroscopy technology combined with thermogravimetric analysis technology and X-ray diffraction technology,etc.to detect the different parameters of clay mineral of montmorillonite,water content and water type,and the spectral characteristics of interlayer cations in the terahertz band.Those indicate the potential ability of terahertz technology in application of mineral characterization.The main contents of this thesis are as follows:(1)Through investigating the terahertz spectral characteristics on the clay mineral of montmorillonite in different thickness samples and using the terahertz time-domain spectrum to determine the method of sample-making and data-processing in subsequent,it ensures the originality of the data.The terahertz time-domain spectroscopy technique is used to characterize montmorillonite samples with different porosity and concentration.The results show that the terahertz time-domain spectroscopy technique can clearly distinguish their porosity and concentration.The change rules of absorption coefficient and index of refraction are also discovered respectively.(2)Basing on the escape temperature of internal adsorption water and interlayer structure water of montmorillonite which is judged by traditional method,it shows that the terahertz timedomain spectroscopy technique can effectively distinguish the montmorillonite products calcined at different temperatures and the montmorillonite samples with different adsorbed water content,using the terahertz time-domain spectroscopy technology to characterize the water content and water type of montmorillonite,It proves that terahertz time-domain spectroscopy is an efficiency method that can be used to study the water type and water content of minerals.(3)Through testing the three montmorillonite samples with different interlayer cations by terahertz time-domain spectroscopy,their spectral characteristics in the terahertz band are obtained respectively.The mean refractive index of the montmorillonite samples with different interlayer cations in the terahertz band is also calculated from it.The result shows that terahertz time-domain spectroscopy can distinguish samples with different interlayer cations effectively and distinguish the interlayer cations of unknown samples based on their spectral characteristics in the terahertz band.