Growth Kinetics of Tetra-N-Butyl Ammonium Bromide Semiclathrate Hydrate through Concentration Determination and Microscopic Observation

Growth kinetics of TBAB semiclathrate forming from 32wt% aqueous solution at 10±1°C and atmospheric pressure was studied through macro concentration determination and microscopic observation. The varied concentration from which the hydrate formed was measured in the range of 32wt% ~ 24wt% by means of weighting method, based on which three-stage hydration process was proposed. The morphology of TBAB hydrate crystals and growing velocity were then investigated based on a microscopic observation system. Coexistent morphology of TBAB semiclathrate hydrate crystals was obtained for the first time, with the single crystals in tetragonous, hexagonous, and octagonous columnar shapes. In the kinetics analysis, the growth velocity of TBAB semiclathrate hydrate crystals was calculated. Equation of the crystal growth for tetragonous and octagonous columnar crystals was worked out in combination of the varied concentration and the growth velocity. And to our best knowledge, no kinetics formula has been reported on the two shapes of TBAB semiclathrate hydrate crystals.