2.5 Characterization
NMR spectra were carried out to analyze the chemical shift of multimer
absorbent and complexes on a Bruker DPX 400 MHz spectrometer with
CDCl3 in the capillary tube as an internal standard
solvent. The viscosities were measured by Brookfield LVDV-II + Pro
viscometer with a deviation of ±1%. The thermal stability of the
multimer absorbent DBU-2EG and DBU-2EG-4H2S complexes
were measured by thermal gravimetric analysis (TGA) using TGA
thermogravimetric analyzer (Mettler Toledo) with the heating rate of
5℃/min in the nitrogen
atmosphere.