Polymer Mediated Crystal Habit Modification

Prevention of crystal growth and modification of crystal morphology in aqueous systems has received considerable attention recently due to changes in the water treatment industry instigated by economic and environmental pressures. Water costs, especially in the western United States, are forcing a shift in the manner that the water is managed. Historically, a concentration of minerals to the point of precipitation was reduced by discharging the process water and making up with fresh water or by altering precipitation kinetics or macroscopic crystal structure of mineral scale via water-soluble polymers. The economic and environmental concerns require the water manager to maximize the number of cycles the process water must experience before being discharged to the environment. This increases the driving force on precipitation in the system and a new generation of polymers must be created that can be effective under these stressed conditions. The use of synthetic polymers has been widespread since the early 1960's and has been our primary focus for several years. We have found that polymers containing substantial amounts of maleic acid are effective calcium carbonate scale inhibitors under these stressed conditions but historically suffer from poor cost effectiveness due to non-aqueous polymerization routes. We have developed polymers containing substantial (>50 mole %) maleic acid prepared via an aqueous polymerization route. The first commercial product from this technology is AQUATREATâ AR-980.