The effect of ethylene glycol additive and growth rate on the capture of water by potassium acid phthalate crystals

The types and quantities of the volatile products formed in cleavage of potassium acid phthalate crystals were detected by mass spectroscopy. The crystals analyzed were grown by conventional and fast-growth techniques from a nominally pure solution and from a solution containing 0.2 wt. % ethylene glycol additive. It was found that the amount of water released from the cleavage surface was reduced from 5.6x1015 to 2x1014 molecules/cm2 with an increase in the growth rate from 0.2 to 2 mm/day, and to 6.6x1013 molecules/cm2 with the addition of ethylene glycol. This effect was attributed to the fact that an increased growth rate and the presence of ethylene glycol hinder ordering of the adsorption layer and, therefore, make the capture of adsorbed water less probable