Synthesis And Scale-Corrosion Inhibition Performance Of Modified Polyepoxysuccinic Acid

As a nitrogen-free,phosphorus-free,biodegradable green water treatment agent,polyepoxysuccinic acid?PESA?has attracted the attention of many scholars in the field of water treatment.However,its the corrosion inhibition performance is not outstanding and the scale inhibition performance needs to be improved,the research of PESA in the future will be mainly focused on the development of scale and corrosion inhibition modified products,with high efficiency and environmental protection.In this paper,the synthesis process of polyepoxysuccinic acid?PESA?was optimized by single factor experiment and orthogonal experiment,and a kind of PESA product with excellent scale inhibition performance against calcium carbonate was obtained.The structure was characterized by IR.At the same time,under the principle of green chemistry,a series of functional materials of multi-component physical modified PESA were obtained by using the self-synthesized PESA as the main agent to select a reasonable compounding agent.The scale-corrosion peinhibition performance and its scale mechanism of PESA were discussed.The main research contents are as follows:?1?Using maleic anhydride as raw material,hydrogen peroxide as the oxidant,sodium tungstate dihydrate as the catalyst,the intermediate product epoxy succinic acid?ESA?is formed by epoxidation under certain conditions,and the final product PESA was obtained by polymerization with calcium hydroxide as initiator.Taking the scale inhibition performance of the product as the evaluation index,the scale inhibition performance of the product to CaCO3 was studied by static scale inhibition method.The basic synthesis conditions of PESA were explored by single factor experiment,and the synthesis conditions were optimized by orthogonal experiment.The optimum synthesis process was:n?maleic anhydride?:n?NaOH?=1:2,cyclization temperature was 70?,polymerization temperature was 90?,the amount of catalyst was 0.035 g,the amount of initiator was 0.075 g,oxidant The dosage was 0.6 mL.?2?The scale inhibition and corrosion inhibition performance of PESA was studied.By calcium carbonate deposition method,the optimum dosage of the agent was determined to be8 mg/L,the optimum scale inhibition temperature and scale inhibition time were 80°C and10 hours respectively,and the optimum concentration of Ca²⁺was 250 mg/L.By rotating the hanging film method,the optimum concentration of single PESA was 25 mg/L,and the annual corrosion rate was 0.545885 mm/a,the corrosion inhibition rate was 40.94%.?3?Using self-synthesized PESA as the main agent,and compounding with Na2MoO4,HEDP,ZnSO4,etc.,the modified PESA formula was obtained by studing the corrosion inhibition performance of modified products against A3 carbon steel through dynamic rotary hanging method.The conclusion was:mass ratio of quaternary component was m?HEDP?:m?PESA?:m?ZnSO4?:m?Na2MoO4?=5:8:19:13,when the dosage was 45mg/L,the annual corrosion rate was 0.01885mm/a,the corrosion inhibition rate was 93.54%.The low phosphorus ternary formula was n?HEDP?:n?PESA?:n?ZnSO4?=5:8:15,when the dosage was48 mg/L,the annual corrosion rate was 0.045885 mm/a,and the corrosion inhibition rate was90.54%.?4?The scale inhibition mechanism of the product was analyzed by SEM,IR and other techniques.The results showed that the polyepoxysuccinic acid has good chelate dispersibility,which can transform CaCO3 scale from stable calcite to unstable vaterite.The corrosion inhibition mechanism of the phisical modified product was analyzed by SEM.The results showed that there was a synergistic effect among PESA,sodium molybdate,HEDP and zinc sulfate.It could be speculated that a composite film was formed on the metal surface,so the A3 carbon steel were better prevented from corrosion.