1H AND 2H NMR STUDY OF THE SYNTHETIZED MESOPOROUS MATERIAL

Low field (0.05 T) 1H and high field (7.04 T) 2H NMR methods were applied to investigate synthetized silica mesoporous materials MCM-41 and SBA-15. The issue is significant in many fields of science and industry e.g. as carriers of contrast agents in medicine or materials used for remediation of the soils. The 1H NMR measurements with short echo time (TE) equal to 60 us were carried out on a 0.05T NMR scanner. The Inverse Laplace Transform with the Lawson and Hanson (L&H) algorithm was applied for determination of 1D distribution of relaxation times, while the 2D maps were calculated using the FISTA algorithm. This approach enabled us to register: T1 and T2 distributions,. as well as T1-T2 maps. Therefore the following parameters: pore size distribution, total and effective NMR porosities and content of different types of water occupying the pores Free Fluid Index (FFI), Bulk Volume Irreducible (BVI), Clay-bound Water (CBW), capillary-bound water were determined. The second approach based on the Gibbs-Thompson equation, which relates the freezing point depression of the liquid contained inside the pores to the pore size. 2H NMR signal intensity corresponding to the amount of confined deuterated acetone and cyclohexane in liquid phase was studied in function of temperature. The 2H NMR resonance frequency was equal to 46 MHz, and a single pulse excitation sequence was used. Using theoretical models NMR permeability was estimated. The T1-T2 maps allowed to determine the representation and mobility of water in the samples. The porosity changes within the samples were estimated with the T2 relaxation time distributions. The results giving insight into the mesoporous materials' structure with the two complementary approaches will be presented and compared with the literature data. The feasibility of the methods, as well as their limitations will be discussed.