Control of Iron(III) Scaling in Industrial Cooling Water Systems by the Use of Maleic Anhydride–Ammonium Allylpolyethoxy Sulphate Dispersant

Abstract

In an attempt to control iron(III) scaling in industrial cooling water systems, a maleic anhydride (M)/ammonium allylpolyethoxy sulphate (S) copolymer (MSn, n = 5, 9, 13, 20) was examined as an environmentally friendly dispersant. The synthesized MSn copolymer was characterized by Fourier-transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA). The ability of MSn to disperse iron(III) increased as the value of n increased from 5 to 13; however, the ethylene oxide chain in MS20 was so long that the molecule readily curled and hence its dispersion capability towards iron(III) decreased. It was also shown that MS13 exhibited the best dispersion activity towards iron(III), with ca. 28% light transmittance being achieved when the dosage of MS13 was 10 mg/l. The proposed dispersion suggests the formation of a core-shell superstructure, with interactions between various kinds of iron ions and the side-chain oxygen atoms of ethylene oxide being the principal means whereby iron(III) may be dis...