Organic phosphonates are a family of compounds widely used as mineral scale and corrosion inhibitors in a variety of applications in industrial processes. The phenomena of scale and corrosion inhibition has been studied extensively. This study reports the tolerance of phosphonates with hardness ions under a variety of test conditions (i.e., temperature, type and concentration of hardness ions, total dissolved solids, etc.). The phosphonates tested include: hydroxyphosphono acetic acid, HPA; aminotris(methylene phosphonic acid), AMP; 1-hydroxyethylidine 1,1-diphosphonic acid, HEDP; 2-phosphono butane 1,2,4-tricarboxylic acid, PBTC; and polyamino polyether methylene phosphonic acid, PAPEMP. It has been found that tolerance of phosphonates with hardness ions strongly depends on phosphonates architecture. Results of this study also show that phosphonate tolerance to hardness ions can be extended by the addition of additives (polymeric and/or non-polymeric) to the aqueous system. Three types of polymers tested include: synthetic (homo-, co-, and terpolymers), biopolymers, and hybrid polymers. It has been found that terpolymer containing hydrophobic and bulkier groups perform better than the homo-, co-, and hybrid polymers.
Keywords: hardness ions, phosphonates, polymers, compatibility, cooling systems