Screening polymer surfaces in crystallization

Abstract

We have used shaken-jar testing to screen the influence of various commercial polymer films on the crystallization of calcium carbonate from a supersaturated mixture containing other salts. Such methodologies and data can inform designs of crystallizers and mixing devices used to increase water recovery during inland desalination, as well as, in cooling tower blowdown and other unit operations wherein sparingly-soluble salts supersaturate. We measured turbidity, surface scale deposition, crystal production, and overall Ca ion material balances to identify how surfaces appear to promote heterogeneous nucleation but not surface build-up (aka scaling). We describe our methodology and the effects from limited results varying contact time and mixing energy. Within the limits of our experiments, we found the unexpected result that polyethylene (PE) and an ethylene vinyl alcohol co-polymer (EVOH-E) equally promoted overall loss of supersaturation to crystallization, but the latter was also highly resistant to scaling.