Synthesis Of Phosphonocarboxylic Acid Polymers And Their Scale Inhibition And Dispersion Properties

With the rapid development of industry in our country,industrial water consumption is increasing,and the use of circulating cooling water is an important way to save industrial water.After the cooling water is continuously circulated and cooled during use,the mineral content of the water will rise,which will easily cause problems such as scaling of the water body and corrosion of the pipeline.Calcium carbonate and calcium phosphate are common scales,which will affect the heat and mass transfer of the pipeline.Iron oxide will rust the pipeline and affect its service life.Usually,a scale inhibitor is applied to inhibit the scale formation of mineral ions in water and increase the use times of circulating water.Therefore,the synthesis of a low-cost,excellent performance,and environmental protection scale inhibitor is the focus and difficult problem to be solved urgently.In this paper,maleic anhydride（MA）and 2-acrylamide-2-methylpropanesulfonic acid（AMPS）are used as raw materials,phosphorous acid（H₃PO₃）is used as a molecular chain transfer agent,and ammonium persulfate is used as an initiator.Solution polymerization is used.MA-AMPS-H₃PO₃（referred to as PMA）terpolymer scale inhibitor was prepared.The scale inhibitor can be used in industrial circulating cooling water with high temperature,high alkalinity,high pH and high Ca²⁺concentration.It has the advantages of simple preparation process,low raw material price,good scale and dispersion resistance,low phosphorus content and stable structure.The main research contents are as follows:The effects of raw material ratio,reaction temperature,reaction time and the amount of initiator on PMA synthesis were investigated.The results showed that the optimal synthesis conditions for PMA were n（MA）:n（AMPS）:n（H₃PO₃）=10:1:10,the reaction temperature was 80℃,the reaction time was 2 h and the amount of initiator was 5%.The highest blocking efficiency of calcium carbonate is 98%.The structure of PMA was characterized by infrared spectrum（FT-IR）and nuclear magnetic resonance carbon spectrum(¹³C NMR).Under the optimal synthesis conditions,the PMA solid content was 6.91%,the intrinsic viscosity number[η]=10.2 mL/g,and the viscosity average molecular weight was 4520.The amount of free phosphorus in PMA measured by ion chromatography is less,and it is more environmentally friendly during use.The experiments of inhibiting the deposition of calcium carbonate scale and dispersing iron oxide were performed on PMA,and the temperature resistance,alkali resistance,salt resistance and calcium tolerance of PMA were investigated.The results show that when the reaction temperature is T=80℃,the reaction time is t=10 h,the reaction pH is9.0,C(Ca²⁺)=240 mg/L and C(HCO₃^-)=732 mg/L,the amount of PMA added is 30mg/L,the efficiency of blocking calcium carbonate scale reached 98%,indicating that it has a low amount of high efficiency in inhibiting calcium carbonate.After examining the single factor,it was found that PMA has better temperature resistance,calcium tolerance,alkali resistance,pH resistance and aging.When the reaction temperature T=50℃,reaction time t=5 h,reaction pH=9.0,C(Ca²⁺)=60 mg/L and C(Fe²⁺)=10mg/L,the added amount of PMA is 18 mg/L The solution has a light transmittance of44%,indicating that it has excellent dispersion properties.And it still has good dispersion performance in high pH,high Ca²⁺concentration and high Fe²⁺concentration solutions.Compared with the scale and dispersion performance of commercially available scale inhibitors,it can be concluded that PMA has better scale and dispersion resistance.