Reaserch On The Preparation And Performance A Novel Scale Inhibitor Composed Of Binary Copolymer MA-AMPS And Organic Phosphonic Acid PBTCA

To insist on sustainable development, clean production and green chemistry,water treatment chemicals--- scale inhibitor is widely used for the prevention and treatment of industrial circulating cooling water system of water quality deterioration, scaling, corrosion and other issues. This research developed a new type of a mixed-type inhibitor which can be used for the treatment of high temperature, high scale, high p H value and high hardness of circulating cooling water.Preparation method of scale inhibitor was determined by experiments. A binary copolymer was synthesized from maleic anhydride(MA), 2-acrylamido-2-methyl propane sulfonic acid(AMPS) by water quadripo lymerization under the existence of redox initiator. By adding 2-phosphonobutane-1,2,4-tricarboxylic acid(PBTCA) as the multiple composition into the copolymer system simultaneously during the copolymerzation, the compound scale inhibitor MA-AMPS/PBTCA was prepared. The effect of the scale inhibitor on inhibiting performance was investigated by static experiments. The optimum technological condition was obtained through the single factor investigation. The optimum synthesis conditions by single factor investigation was as follows: MA, AMPS and PBTC A dosage was 60%wt, 40%wt and 20%wt, reaction temperature at 70℃~75℃ and the dosage of initiator between 12%~14%wt. Refer to the single factor experimental results, select the four main factors and the three parameters levels orthogonal experiments. The resistance efficiency of calcium carbonate scale as the index of the optimum reaction conditions, The results revealed that, while the m(MA) : m(AMPS) : m(PBTCA) = 5 : 2 : 3, the initiator dosage at 12%wt, the reaction temperature at 80℃, with sodium persulfate as the oxidant, the resistance efficiency of calcium carbonate scale was more than 79%. Meanwhile, in the resistance of calcium phosphate scale, the optimum reaction conditions was as follows: m(MA) : m(AMPS) : m(PBTCA) = 5 : 2 : 2, the initiator dosage at 12%wt, the reaction temperature at 70℃, with ammonium persulfate or sodium persulfate as the oxidant. Under this condition, the resistance efficiency of calcium phosphate scale was above 95%.The application conditions of the scale inhibitors were also investigated. The results showed that, even the calcium ion concentration in the wastewater was high to 400 mg/L, its resistance efficiency to calcium carbonate and calcium phosphate scale could still reach to 70%. Under the condition of pH = 8.5, water temperature between 80℃~85℃, water bath time of 10 hours, the resistance efficiency of the scale inhibitors to calcium carbonate and calcium phosphate scale was 78%~82% 、96%~99.5%, respectively. At the above conditions, when the dose of compound scale inhibitor(MA-AMPS/PBTC A) was at 80mg/L, the resistance efficiency to calcium carbonate scale reached to 94%. Compared with the commercially available scale inhibitors, the prepared scale inhibitor had the adva ntagement of better scale inhibition performance, low production cost, no phosphine pollution. It is more suitable to be used in industrial circulating cooling water treatment.The structure of the scale inhibitor and calcium scale was characterized by FTI R, and their thermal stability was analyzed by TG. The scaling resistance effect of the inhibitor on CaCO3、Ca3(PO4)2 was explained by combined with the results of XRD, SEM and FTIR characterization. The FTIR characterization result showed that the mixed-type inhibitor contained the functional groups structure of MA, AMPS and PBTC A, which demonstrated that the target product MA-AMPS binary copolymer was produced and the compound scale inhibitor was composed of MA-AMPS copolymer and organic phosphonic acid PBTC A. The TG analysis showed that the compound scale inhibitor had a good thermal stability with the thermal decomposition temperature high to 276℃, indicating that it could be used in high temperature industrial circulating cooling water treatment system. The XRD and SEM characterization results revealed that the calcite was inhibited and the meta-stable vaterite was stabilized in the presence of the copolymer during the formation of CaCO3. The normal growth of calcium phosphate scale was destroyed by the inhibitor, which led to the surface of the scale became loose and in clusters. Therefore, the scale inhibition mechanism might be interpreted that the addition of the inhibitor would cause to the structure distortion of the scale and the damage of the dirt surface.