Potential kinetic model for scaling and scale inhibition mechanism

Scale deposition occurs when dissolved salts precipitate from aqueous solution. Scale formation is reported to occur by two pathways, surface crystallization & bulk crystallization. Scaling in pipe system is a combination of these two mechanisms and is affected by process conditions in the pipe. This paper examines the mechanism responsible for scale inhibition and explores the effects of maleic anhydride based polymers (YMR-series) on the various scaling pathways. The aim is to develop a kinetic model for scale inhibition mechanism which can lead to improved predictive capabilities and, provide reliable methods/framework for interpreting experimental data. Results indicated that higher temperature produced a large increase of scale amounts and a significant decrease of induction periods. The relationship between deposited scale mass and temperature was deduced from experimental data. From the kinetic model-II activation energies for nucleation in the presence of scale inhibitor is 136-137.9 kJ/mol (CaCO3 scales) and 141-146 kJ/mol (CaSO4 scales); E-a for crystallization phase is 30-33.8 kJ/mol for CaCO3 and 40-60 kJ/mol for CaSO4 scales at 0.15 mol/L for copper & steel pipes. Estimated E-a was compared with literature model, and the present model represents the data with acceptable accuracy of error less than 2%. (C) 2015 Elsevier B.V. All rights reserved.