Study On The Effect Of Magnetic Field And Environmental Friendly Agents On Crystallization Process And Crystal Of Calcium Carbonate

Magnetic treatment technique is a promising method for water treatment and has many characteristics, such as scale inhibition, corrosion inhibition. The environmental friendly polymer, which is biodegradable, non-phosphorus and good environmentally compatible, represents the development direction of inhibitors. In this paper, the crystallization process and change of crystal structure of calcium carbonate were studied by electrical conductivity analysis, X-ray diffraction (XRD), scanning electron microscopy (SEM) and infrared spectroscopy (IR). The crystallization process and change of crystal structure of calcium carbonate were discussed using polyepoxysuccinic acid (PESA), polyaspartic acid(PASP) and Mg²⁺ combined with magnetic treatment technique, respectively. This provides a theoretical basis for the development of chemical-physical processing technique in circulating cooling water system. This dissertation consists of 6 chapters.Chapter one: Introduction. The research progresses of magnetic treatment technique and inhibitors including PESA, PASP and Mg²⁺ in recent years were summarized with 60 references. The objective and significance of this dissertation were described in brief.Chapter two: Experimental method. The principle, experimental conditions of instruments and date processing methods of conductivity analysis, XRD, SEM and IR were described in this chapter.Chapter three: Study on the effect of magnetic field on crystallization process and crystal of calcium carbonate. The crystallization process and crystal of CaCO₃ were investigated with the magnetic treatment under the different conditions. The results showed that the magnetic field could accelerate the formation of crystallization of CaCO₃ and promote the conversion of calcite to aragonite.Chapter four: Study on the effect of polyepoxysuccinic acid and magnetic treatment on calcium carbonate. The crystal of CaCO₃ was investigated with magnetic treatment at the different concentration of PESA, and the scale prevention mechanism of PESA was discussed. The results showed that PESA could prevent crystallization of CaCO₃ and reduce the formation of scale. The crystal structure of CaCO₃ was fractured,and particle distribution was more loose using the combination of PESA and magnetic treatment. This result showed that magnetic field and PESA played a synergistic effect, and the formation of hard scale was more difficult.Chapter five: Study on the effect of polyaspartic acid and magnetic treatment on calcium carbonate. The crystal of CaCO₃ was investigated using the magnetic treatment combined with different concentration of PASP, and the scale prevention mechanism of PASP was discussed. The results showed that PESA could inhibite crystallization of CaCO₃,reduce the formation of scale and lead to lattice distortion. Using the combination of PESA and magnetic treatment, the formation of hard scale was more difficult because of the co-exist of calcite, aragonite and vaterite.Chapter six: Study on the effect of Mg²⁺ and magnetic treatment on calcium carbonate. The crystal of CaCO₃ was investigated using the magnetic treatment combined with different concentration of Mg²⁺ and the scale prevention mechanism of Mg²⁺ was discussed. The formation of calcite was inhibited when the concentration of Mg²⁺ was more than 0.5 mmol·L^-1,and the result showed that Mg²⁺ and magnetic field played a synergistic effect.