Synthesis And Scale Performance Research Of New Scale Inhibitors

There are serious scaling problems in industrial recycling cooling system and other industrial pipelines, leading to low productive efficiency and high energy consumption. The application of antiscaling agents is the most-optimal method to prevent the formation of scaling. This paper mainly synthesizes three kinds of scale inhibitors, they are diethylene triamine pentamethylene phosphonic acid,sulfo group modified polymaleic acid and ethylenediamine grafted acrylic- methacrylate polymer. The synthesized compounds were characterized by infrared spectrum(IR), thermogravimetric(TG)、X-ray photoelectron spectroscopy(XPS) and electrospray mass spectrum(ES-MS). The main works can be summarized as follows:The synthesis of diethylenetriamine pentamethylene phosphonic acid(DETPMP) was carried out by one-pot reaction of diethylene triamine, formaldehyde and phosphorous acid under the catalysis of hydrochloric acid. The synthesized DETPMP products at different reaction times were analyzed by ES-MS mass spectroscopy and isotope analysis. The relative content of DETPMP in the reaction mixture was obtained by analyzing the mass spectra and comparing experimental and theoretical isotope spectra. The optimum conditions for obtaining the products containing more DETPMP molecules are: 1:10:5 mole ratio of diethylene triamine, formaldehyde and phosphorous acid, temperature 100-105°C and reaction time 4 h. And the sodium salt(DETPMPS) of DETPMP was obtained by mixing DETPMP with 40% sodium hydroxide solution. Moreover, the effect of the concentration of the synthesized DETPMPS and DETPMP on the inhibition rate to calcium sulfate was studied. The results show that the inhibition rate of DETPMPS is 94.55% after adding the 10 mg/L DETPMPS in the solution containing calcium 1.51 g/L.Orthogonal experimental method was used in this experiment to study the synthesis and scale performance of sulfo group modified polymaleic acid(MA-SAS). The optimal conditions for the synthesis of MA-SAS polymer based on scale performance are as follows: the molar ratio of maleic anhydride, sodium allyl sulfonate and sodium hydroxide is 1:0.05:1.8; potassium persulfate accounted for 4% of the quality of maleic anhydride and the reaction temperature is 85 ?C. The best scale inhibition rate to calcium sulphate was 90.06%. And the comparative experiments between synthetic polymaleic anhydride and maleic anhydride- allylsulfonate under the same conditions indicate that the introduction of-SO3 groups improves the inhibition efficiency of polymaleic acid. The results also illustrate that the synthesized inhibitor has high inhibition rate within the range of 60–70 °C, but not suitable for high temperature environments.Acrylate-methacrylate polymer was synthesized with azobisisobutyronitrile as initiator, and then ethylenediamine grafted acrylic-methacrylate polymer(P-AAMA-EDA) was obtained by amide reaction. P-AAMA-EDA exhibited excellent inhibitory efficiency with 84% calcium carbonate inhibition at dosage of 6 mg/L, whereas the popular inhibitors of PAA, HPMA and T-225 exhibited only 20-60% calcium carbonate inhibition and AA-APEC reported in literature approximately 65%. At lower concentrations, P-AAMA-EDA displays superior ability to inhibit the precipitation of calcium sulfate, with 80% inhibition at a level of 0.5 mg/L, whereas it is 55% for PAA and PESA and only 20% for AMPS at the same dosage, respectively. Furthermore, the inhibition mechanism toward CaCO3 and CaSO4 deposits was proposed. The high inhibition efficiency of P-AAMA-EDA is ascribed to the synergistic effect of carboxyl and amino groups in the P-AAMA-EDA matrix.