Synthesis and application of terpolymer scale inhibitor in the presence of β-cyclodextrins

• Preparation of water-soluble terpolymer scale inhibitor.
• Optimization of preparing polymer based on orthogonal and single factor experiment.
• Characterizations of FT-IR and UV–vis spectra.
• The inhibition efficiency to calcium carbonate scale and calcium phosphate scale.
• Scale inhibition mechanism.

A water-soluble modification of β-CD–MA was prepared via the reaction of beta cyclodextrins (β-CD) and maleic anhydride (MA). Then, a novel terpolymer scale inhibitor β-CD–MA–SSS was synthesized based on β-CD–MA and styrene p-sulfonic sodium (SSS) as monomers, water as solvent, and ammonium persulfate as initiator by the free-radical polymerization. The effects of content of monomer and initiator, reaction time, reaction temperature to inhibit calcium carbonate scale were studied by the orthogonal and single factor experiments. The structure and morphology of the terpolymer were characterized by FT-IR, UV–vis spectroscopy and TEM. Using the static experiment and the malachite green photometric methods, the scale inhibition efficiencies for CaCO3 and Ca3(PO4)2 scale were investigated. The iron dispersing ability measured through the UV spectroscopy was found to be excellent. TEM analyses proved the morphological changes of the CaCO3 scale due to strong inhibition action. The experimental results showed that the β-CD–MA–SSS terpolymer had an excellent efficiency of scale inhibition, and nearly 99.9% of scale inhibition efficiency for CaCO3 and 95.5% for Ca3(PO4)2 were obtained. The prepared terpolymer scale inhibitor could be used in the system of high temperature and high hardness water.