title: Rotating cylinder technique for assessing the effectiveness of anti-scalants.
abstract: A novel technique for evaluating the relative inhibition effectiveness of different anti-scalants is presented. The technique is based on the ability of anti-scalants to modify the scale deposition mechanism from mass transfer control to surface control. A rotating cylinder system which is known to provide well controlled mass transfer conditions is used to determine the scaling rate of a supersaturated solution dosed with various feed concentrations of an anti-scalant. Mass transfer conditions were characterized by turbulent flow at hydrodynamically smooth surface. In the absence of an anti-scalant, scale deposition is mass transfer controlled and scaling rate increases with rotation speed. With sufficient anti-scalant dosage, precipitation is modified to surface control and rotation speed has no effect on the scale deposition rate. Determination of the critical anti-scalant dosage enabling surface controlled precipitation provides a sensitive technique for comparing the relative effectiveness of different anti-scalants.
authors.affiliation: Technion-Israel Institute of Technology, Department of Chemical Engineering, Rabin Desalination Laboratory-Grand Water Research Institute, Haifa 32000, Israel.
authors.forename: Irina
authors.initials: I
authors.lastname: Zaslavschi
authors.forename: Hilla
authors.initials: H
authors.lastname: Shemer
authors.forename: David
authors.initials: D
authors.lastname: Hasson
authors.forename: Raphael
authors.initials: R
authors.lastname: Semiat
mesh_terms: D002119:Calcium Carbonate / Q000737:chemistry; D002133:Calcium Sulfate / Q000737:chemistry; D002138:Calibration; D011232:Chemical Precipitation; D004867:Equipment Design; D057446:Hydrodynamics; D007700:Kinetics; D010825:Physics / Q000295:instrumentation / Q000379:methods*; D012399:Rotation; D014867:Water / Q000737:chemistry*
chemical_list: D014867:Water; D002119:Calcium Carbonate; D002133:Calcium Sulfate