Synthesis and performance of a non-phosphorus antiscalant of acrylic acid/ammonium allylnonylphenol polyether sulphate

Key words: 
• non-phosphorus antiscalant /
• calcium phosphate /
• ammonium allylnonylphenol polyether sulphate

Abstract: Ammonium allylnonylphenol polyether sulphate/acrylic acid (TS-10/AA), a non-phosphorus antiscalant for calcium phosphate, was synthesized by using AA and TS-10 (10 is the number of repeating unit of ethylene oxygen) as monomers and ammonium persulfate as initiator. The product was characterized by FT-IR. The performance on calcium phosphate inhibition was evaluated by the static scale-inhibiting method. The influence of monomer ratio, TS-10/AA dose and biocide on calcium phosphate inhibition was investigated. Calcium phosphate inhibition as a function of solution pH value, Ca2+, Fe2+, PO3-4 concentration was also investigated. The study indicated that TS-10/AA had superior ability to inhibit the precipitation of calcium phosphate when m(TS-10)∶m(AA) was 3∶1. TS-10/AA had still superior ability to inhibit calcium phosphate precipitation under the condition of high Ca2+, Fe2+ concentration and high solution pH value and it had excellent compatibility with the biocide of different thiazolidinone. There was threshold dosage and approximately 99.3% inhibition on calcium phosphate when the dosage was 8 mg/L. Scanning electron microscope showed a disordered calcium phosphate crystal in the presence of TS-10/AA. Inhibition mechanism was proposed that,ethylene oxygen segments increased solubility of TS-10/AA, the interactions between all kinds of calcium ions in systems and carboxyl groups on side chains were the fundamental impetus to restrain the formation of calcium phosphate scale. The study indicated TS-10/AA would be a superior non-phosphorus antiscalant in cooling water systems.