The Study Of Synthesis And Scale Inhibition Mechanics Of Contamination Free Scale Inhibitor Polyepoxysuccinic Acid

Polyepoxysuccinic acid(PESA) is a kind of contamination free scale inhibitor,which was exploited in the 90's, last century. It is wildly used as a new product ofscale inhibitor at present for its excellent scale inhibition, biodegradability andunique molecular structure having no hetero-atoms such as nitrogen and phosphorus.In this paper, PESA was synthesized through epcxidation and epoxy breakingpolymerization from the raw material maleic anhydride, which included two steps:The synthesis of epoxysuccinic acid (ESA) and the polymerization of ESA. Duringthe first step, the content of tartaric acid and maleic acid unreacted were determinedby spectrophotometer, and then the yield of epoxysuccinic acid was calculated. Theinfluence of technological parameter to the yield of ESA was investigated throughexperimental design, and the optimized synthetically technology of ESA wasachieved. In the second step, ESA was polymerized using initiator. Systematicalexperiments were carried out to investigate the influence of technological parameterto scale inhibition of PESA. A preferable polymerization technology of PESA wasachieved.The molecular structure of ESA and PESA was characterized by infra-redspectrometry. It was revealed that there was epoxy in ESA molecules. However thewave crest of epoxy disappeared in IR spectrum of PESA and was taken the place ofthe wave crest of ether link. It showed that ESA polymerized though epoxy breaking.The product was proved to have the same molecular structure with PESA by¹³C-NMR.The property of CaCO3 inhibition of PESA was investigated by static tests whichrevealed that PESA has high scale inhibition performance, and is suitable for high pH value and hard water.Calcium carbonate crystal parameter and morphology was investigated by X-raydiffraction (XRD) and Scanning Electron Microscopy (SEM). It was revealed thatwhen PESA was added, the crystal of calcium carbonate was deformed from calciteto aragonite and vaterite, and the morphology of the scale of calcium carbonate wasturned from compact hard scale to loose soft scale, which could be easily washed offby water scouring. The effect of PESA to the induction period of calcium carbonatescaling was also studied, it was revealed that PESA could increase the potentialbarrier of calcium carbonate scaling to hold the Ca²⁺ in the water longer time, basedon which the scale inhibition mechanism of PESA was discussed.