Study On Chelating Properties And Dissolving Capability Of Epoxysuccinate

This work is a part of the research from the Key Technology R&D Programme. We investigated the chelating properties of epoxysuccinic acid (ESA), the monomer of polyepoxysuccinic(PESA), in order to apply the basic datas for the further research on the constructures and properties of PESA. In this article the determination of calcium chelating with ESA have been studied and the reasonable analytical conditions have been selected. HCl-HNO3 pretreatment-complexometric titration, H2O2-HNO3 pretreatment- complexometric titration and complex agent complexometric titration are applied to the determination of chelating calcium in ESA for the first time. The precision and recovery of the three methods have been discussed.The chelating properties and dissolving capability of ESA under different conditions have been studied. We have found that ESA can be used as chelator under high temperatures. The chelating with CaCO3 is prefered to take place in the solution pH≤7, while the chelating with CaSO4 is prefered to happened in the solution pH closed to 7. The chelated calcium is oberserved to improve significantly with the increase of the the interface area to the reaction mixture. The effect of the concentration of ESA is insignificant. In this article, we obtained the maximum dissolving capability of epoxysuccinate by optimized the chelating conditions. The maximum calcium dissovling value is 318.75mg/g which is larger than the maximum value of EDTA. ESA is confirmed to be an excellent chelator for calcium by the results.The kinetics of the chelating of ESA with CaCO3 and CaSO4 have been investigated in this paper for the first time. The investigations have indicated the two reactions to be first order. The numerical values of the constants are obtained as k1=4.47 ×10-3/min, k2=2.292×10-2/min.