Study On Synthesis And Scale Inhibition Performance Of Green Water Treatment Agent Polyepoxysuceunic Acid

As green water treatment agent with fine biological degradation, polyepoxysuccinic acid (PESA) do not contain phosphorus or nitrogen and has double performance of scale and corrosion inhibition. These advantages make such water treatment chemicals become the main topic in the research field of water treatment chemicals in the future.Nowadays, epoxysuccinic acid is normally used as the source material to synthesize PESA in one step in the other countries. In our country, maleic anhydride is adopted as the source material to synthesize PESA in two steps, as epoxysuccinic acid is not an elementary chemical material.In this paper, polyepoxysuccinic acid is prepared by hydrolysis of maleic anhydride to maleic acid, catalytic oxidization to epoxysuccinic acid and then treatment with alkaline calcium compound. Both the intermediate product and the final product are characterized by IR and ¹³CNMR,¹HNMR. Scale inhibitions of PESA are evaluated by rotary coupon test. And its viscosity is also tested. Accordingly, the relationship between the viscosity and scale inhibitions of PESA is determined. In addition, scale inhibitions ratio as a function of the content of the scale inhibitors and the concentration of Ca²⁺ and HCO₃^- are discussed.Orthogonal experiments are adopted to optimize the technical conditions of synthesis process. The optimal synthesis conditions are as follows: molar ratio of NaOH to maleic anhydride (1.8-2.2) : 1, molar ratio of catalyst to maleic anhydride (0.008-0.012) :1, amount of H₂O₂ 12mL, epoxidation time 1.5-2.5h, reaction temperature 70-85℃ and yield ratio about 98.5%.A quadratic orthogonal regression design is arranged to study the technical conditions of final product.The optimal test synthetic conditions are that molar ratio of solicitation reagent to maleic anhydride (0.071-0.086) :1, polymeric temperature 82-86℃, polymeric time 2.8-3.2h. Under the optimal synthesis conditions, the scale inhibition ratio can reach to above 94% and the viscosity changes from 5.5 to 5.8cP.