title: Assessment of novel maleic anhydride copolymers prepared via nitroxide-mediated radical polymerization as CaSO4crystal growth inhibitors.
abstract: Calcium sulfate is one of the dominant scales which, unlike carbonate scale, are not easily removable by acid. To inhibit CaSO4scale formation in artificial cooling water systems, well-defined low molecular weight maleic anhydride and n-alkylacrylamide copolymers (YMR-S series) were synthesized via nitroxide-mediated radical polymerization initiated by benzoyl peroxide in the presence of 2,2,6,6-tetramethyl-1-piperidinyloxy at varying concentrations. These polymerizations exhibit living polymerization characteristics; that is, they show linear growth in chain length as a function of monomer conversion, and have narrow molecular weight distributions. Resultant polymers were characterized by means of1H-NMR and13C-NMR. The inhibition behavior of these YMR-S series polymers against CaSO4was evaluated using the static scale inhibition method and a dynamic tube block test. The inhibition ability on the CaSO4scale is 99.5% with 9 ppm dosage level at pH 10.45 and temperature 70°C. Scanning electronic microscope analysis proved the morphological changes of the CaSO4scales due to the strong inhibition action of YMR-S polymers. It is also observed that the antiscaling effect of the copolymers greatly depends on the molecular weight, and the optimum range is below 20,000 and approximately in the range 500-2000.
authors.affiliation: a Chemical Engineering Department , Kuwait University , Safat , Kuwait.
authors.forename: Yousef Mohammad
authors.initials: YM
authors.lastname: Al-Roomi
authors.affiliation: a Chemical Engineering Department , Kuwait University , Safat , Kuwait.
authors.forename: Kaneez Fatema
authors.initials: KF
authors.lastname: Hussain
mesh_terms: D020106:Acrylamide / Q000737:chemistry; D002118:Calcium / Q000737:chemistry; D002133:Calcium Sulfate / Q000737:chemistry*; D003460:Crystallization; D003497:Cyclic N-Oxides / Q000737:chemistry; D005609:Free Radicals; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D008299:Maleic Anhydrides / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D008970:Molecular Weight; D009569:Nitric Oxide / Q000737:chemistry*; D009589:Nitrogen Oxides / Q000737:chemistry; D058105:Polymerization; D011108:Polymers / Q000737:chemistry*; D013696:Temperature; D014867:Water / Q000737:chemistry; D014992:Xylenes / Q000737:chemistry
chemical_list: D003497:Cyclic N-Oxides; D005609:Free Radicals; D008299:Maleic Anhydrides; D009589:Nitrogen Oxides; D011108:Polymers; D014992:Xylenes; D014867:Water; D020106:Acrylamide; D009569:Nitric Oxide; C039900:nitroxyl; D002118:Calcium; C003959:TEMPO; D002133:Calcium Sulfate
keywords: CaSO4 scale inhibition; Maleic anhydride copolymers; NMRP; kinetics; static scale inhibition test; tube block test