The crystallization of clathrate aqueous solutions in presence of additives and surfactants

摘要

The crystallization of the TBAB clathrate solutions was investigated with the aim of finding optimal ways of initiation and control of the crystallization process and obtaining structural stability of the slurry during repeatable thermal cycling in technology applicable temperature range. We succeeded in composing and investigating of Tetrabutylammonium Bromide (TBAB) aqueous solutions in various concentrations (from 5÷40 wt%, while the optimal concentration is at 10 wt%). Minor quantities of surfactants containing Br- or Cl- anions were responsible for better structuring and stability of the TBAB emulsions formed. The additives of NH{sub}4Br, NH{sub}4Cl, NH{sub}4F and/or the respective alkaline salts NaCl, KBr, guaranteed the necessary temperature range of crystallization and pH-values of the TBAB slurry solutions for improving adsorption of the surfactants and optimal crystallization. The additives were active in initiating controlled crystallization in the phase transition temperature range between 2÷17°C of either the TBAB or of its fluorine or chlorine modifications.