Synthesis And Properties Evaluation Of Polycarboxylic Acids Containing Sulfonic Group Used As Scale Inhibitor And Ddispersant

Two new polycarboxylic acids containing sulfonic group used as scale inhibitor and dispersant were designed, and its synthesis and scale performance were studied. Effects of reacting conditions and changes of water quality on the inhibition of the polymeric scale inhibitors were also discussed. The tercopolymer was characterized by IR, NMR, Elemental analysis and TG. Using the static experiment method, the scale inhibition performance to CaCO3, BaSO4, SrSO4 and the dispersion efficiency for Fe2O3 were studied.The water-soluble polymers were prepared by solution polymerization techniques with water as solvent and persulfate (NH4)2S2O8 as initiator. The monomers are methacrylate (MAA) or maleic anhydride (MA), sodium methacrylate (SMA), methacryloyl iminodiacetic acid (MAIDA) and two inhibitors are obtained as MAA-MAIDA-SMA and MA-MAIDA-SMA. The effects of the momomer ratio, initiator amount, reaction temperature and reaction time on the synthesis and antiscale abilities were invigated. The results showed that the optimum synthesis conditions were as follows:n(MAA, MA):n(MAIDA):n(SMA)=3:1:1, m ((NH4)2S2O8): m(MAA+MAIDA+SMA)= 8%, reaction temperature 80-90℃, reaction time 2h; the tercopolymers began to decompose at 350℃, which showed the tercopolymers had good heat resistance;Theic results of stat scale experiments showed that the performance of tercopolymers were fairly good at inhibition the deposition of CaCO3, BaSO4 and SrSO4. Being an excellent scale inhibitor for CaCO3, the inhibition capability of this tercopolymer reached 96.3% at the dose of 15 mg/L; the inhibition capability of this tercopolymer for BaSO4 reached 96.3% at the dose of 13 mg/L and 100% for SrSO4 under the dose of 80 mg/L. The MA-MAIDA-SMA tercopolymer had better properties of inhibiting CaCO3, BaSO4 and SrSO4 at the same conditions; the scale inhibition efficiency can be up to 96.4% under the dose of 6 mg/L,100% the dose of 4 mg/L and 100% the dose of 40 mg/L. Additionally, its capabilities of dispersing Fe2O3 was quite well. The changes of water quality such as polymer concentration, ion concentration, pH value and temperature brought great effects on the scale inhibition efficiency. Both copolymers have a good calcium tolerance, the scale was still able to reach more than 90%, when p(Ca2+)=1000 mg/LSEM micrographs further showed that the copolymer changed the crystal morphology of calcium carbonate. The morphology of calcium carbonate scale with the presence of the MA-MAIDA-SMA is not in order any more. The crystal morphology was completely destroyed, and the scales become loose, spongy and amorphous and the mechanism of scale inhibition was discussed.