식용 계면활성제 첨가에 따른 해수 중 HFC-134a 하이드레이트 형성에 관한 연구

Abstract

At the present, there are several primary methods used in seawater desalination; multi-stage distillation, reverse osmosis, etc. Those methods require a large amount of fuel and electric power, and thus a rather novel technology using gas hydrate formation has recently emerged as an alternative. With the advantages such as environment-friendliness and low operational cost, this technology is still struggling to solve several practical operational challenges. Among them, I was focused on the slow kinetics of gas hydrate formation, which would critically affect the throughput (productivity) of the whole process. Gas hydrates are inclusion compounds with the cage structure formed by hydrogen bonding of water molecules at low temperature (but, above the normal freezing point of water) and high pressure. Objective gas can be any of methane, ethane, propane, HFC, HCFC, etc. According to the size of objective gas combined with cage type of water molecules, there exist three different structures; so called, structure I (sI), structure II (sII), and the structure H (sH). Returning back to the point, I was to improve the kinetics of gas hydrate formation by using promotors. Because this study has to be incorporated to the development of desalination process producing potable water, three kinds of edible surfactants were selected as promotors; lecithin from amphoteric surfactants, carrageenan and polysorbate80 from anionic surfactants. Non-edible cationic surfactants were excluded. Then, the kinetics of R-134a hydrate formation was checked out by varying the concentration of surfactants and the salinity of seawater. Surfactants were supposed to decrease the surface tension of water molecules on the interface of hydrate particles and liquid. From the experimental results, it was clearly observed that the rate of R-134a hydrate formation increases with the addition of edible surfactants as expected. The effect as a promotor has an order; carrageenan = polysorbate80 > lecithin.