A novel phosphorus-free and nitrogen-free anti-scalant for calcium phosphate and Fe(Ⅲ)

maleic anhydride/allyl polyethylene glycol carboxylate (MCn

n is the degree of polymerization of polyethylene glycol

n=5

9

13)

was synthesized from allyl polyethylene glycol monoether

chloracetic acid

maleic anhydride

and sodium hydroxide.The product was characterized by FT-IR and 1H-NMR.The performance of calcium phosphate inhibition and dispersancy towards Fe(Ⅲ）was evaluated by the static scale-inhibiting method and light transmittance

respectively.SEM analysis showed a disordered calcium phosphate crystal in the presence of MCn.The studies indicated that both inhibition and dispersancy increased with increasing degree of polymerization of polyethylene glycol in the structure of MCn from 5 to  13.MC13 had superior ability to inhibit the precipitation of calcium phosphate

approximately 99% inhibition when the dosage was 6 mg·L-1

and had excellent dispersancy towards Fe(Ⅲ)

about 22% light transmittance when the dosage was 8 mg·L-1.Inhibition mechanism was proposed that the interactions between all kinds of metallic ions in systems and carboxyl groups on side chains and/or oxygen atoms of ethers were the fundamental impetus to restrain the formation of calcium phosphate scale and disperse Fe(Ⅲ）in cooling water systems.