Synthesis Of Alkyl Epoxy Carboxylate And Study On The Static And Dynamic Scale Inhibition Performance Of Carboxylic Acid Functional Groups

In the first part of this paper, ten kinds of alkyl epoxy carboxylate?AEC-n? are synthesized with fatty alcohol polyoxyethylene ether?AEO-n, n = 3, 4, 5, 7, 9, 10, 11, 12, 15, 20?, sodium chloride and sodium hydroxide as monomer and ethanol as solvent. The optimum conditions of the reaction are investigated by using the experiment, and the optimum conditions are: the molar ratio of AEO: sodium chloroacetate: sodium hydroxide is 1:1.05:1.1, the reaction temperature range is 45-55 °C, and the reaction time is 3.5 h.The inhibition performance of ethylene alkyl carboxylate?AEC-n? against CaCO₃, CaSO₄ and Ca₃?PO₄?₂ scale are evaluated in the static scale experiment, and the effects of external conditions, such as temperature, concentration, pH and concentration ratio on inhibiting calcium carbonate scale are investigated. The results show that when AEC-n has the same molecular structure, the scale inhibition against calcium carbonate scale depends largely on the EO number of AEC, and decreases with the increase in the EO number; as the EO number is less than 12, AEC-3, AEC-4, AEC-5, AEC-7, AEC-9, AEC-10 and AEC-11 can be used significantly to inhibit the formation of CaCO₃ scale; while the EO number is 4 or 5, AEC-4 and AEC-5 are good inhibitors against CaSO₄ scale; but as the EO number is less than 6, AEC-3, AEC-4 and AEC-5 show good performance in inhibition of Ca₃?PO₄?₂ scale; generally AEC-3, AEC-4 and AEC-5 can be used in high alkalinity and high hardness water.The effects of the EO group in AEC molecule on the corrosion inhibition of carbon steel are studied using weight loss of rotating hung steel slices. It is found that AEC is an anion-non-ionic corrosion inhibitor, and its corrosion inhibition performance presents as a significant critical threshold effect. With the increase of the EO number, its corrosion inhibition performance increases continuously. It suggests that the corrosion inhibition of AEC actually depends on the EO number of AEC.The effects of AEC on CaCO₃, CaSO₄ and Ca₃?PO₄?₂ morphology using scanning electron microscopy?SEM? are investigated, and it is found that its scale inhibition mechanism is owing to the lattice distortion and dispersion. The inhibition mechanism of carboxylic acid functional group is mainly attributed to the adsorption of calcium carbonate on the microcrystalline, therefore the normal growth of the crystal lattice is distorted, and crystal growth is destroyed. The adsorption of carboxylic acid depends on its electrical negative, and its electrical negative affects by other functional groups, the greater the electronegativity of other functional groups is, the stronger the effect of the carboxylic acid. The interaction between EO group and carboxylic ion may actually play a leading role, it determines the capability of carboxylic ion adsorbing on the CaCO₃ crystal, and this capability actually depends on the EO number, the bigger the EO number is, the weaker the interaction.In the second part of this paper, the influence of scale inhibition of HPMA on calcium sulfate scale is studied. Under conditions close to the real working conditions, the effects of two factors, such as dosage and concentration of CaSO₄ solution on the heat transfer characteristics of the test tube made by 316 L stainless steel are investigated. The results show that when the concentration of CaSO₄ solution is less than 1360 mg/L, the scale growth rate gradually decreases with the increase in adding ratio???; as adding ratio exceeds ? = 3/1360 and the solution concentration is less than 1360 mg/L, the scale growth rate increases with increasing CaSO₄ solution concentration; but with ??? is a molar ratio of carboxylic acid and calcium sulfate? increasing, the scale growth rate decreases steadily; while as the concentration of CaSO₄ solution is 816, 1088, 1360, 2720 and 4080 mg/L, the corresponding ? is 5.6, 7.3, 5.8, 6.9 and 7.6, respectively, which indicates that HPMA molecular complexed of Ca²⁺ ions has reached the maximum capacity, and the lower concentration of the solution is, the larger the capacity of Ca²⁺ ions. Experimental correlations between d?K/K0?/dt, ? and CaSO₄ concentration are obtained finally, which will provide some theoretical guidance for the practical application of carboxylic acid inhibitors.