摘要
对氯柱硼镁石(2MgO·2B_2O_3·MgCl_2·14H_2O)在30℃时水中溶解和相转化过程的研究结果表明,该复盐在水中呈现不同步溶解.首先溶脱掉MgCl_2·6H_2O,生成中间产物MgO·B_2O_3·4H_2O.随后发生转化,最终结晶产物是多水硼镁石.在给出溶解转化结晶动力学方程的基础上提出溶解转化结晶反应机制.
The kinetics of dissolution and transformation process of 2MgO · 2B2O3 · MgCl2 · 14H2O in water at 30℃ has been studied in a multincck flask with a liquid sealed stirrer. During the experiment, the solution samples were taken at different times for chemical analysis and the pH value, electric conductivities and the EMF values of chlorine ion in the solutions were determined respectively. The solid phases at different stages were separated and identified by chemical analysis, X-ray powder-diffraction and IR-spectrography.
The kinetic C-t curve and pH-t curve can be clearly divided into five parts: dissolution, dissolution equilibrium, transformation, crystallization and crystallization equilibrium. The experimental results showed that 2MgO · 2B2O3 · MgCl2 · 14H2O dissolved incongruently in water, it means that during the dissolution of 2MgO · 2B2O3 · MgCl2 · 14H2O, its constituent, MgCl2 · 6H2O, is removed firstly and the resulting intermediate product, MgO · B2O3 · 4H2O and the hydrolyzcd product, Mg(OH)2, can be obtained. The final crystallized product is inderite, 2MgO · 3B2O3 · 15H2O.
The experimental data of the dissolution process and the final crystallization process have been fitted by the general kinetic equations with the aid of Simplex Optimum Method and Runge-Kutta Digital Solution of differential equation system, and then , the kinetic equations of dissolution and crystallization have been obtained. At last, the reaction mechanisms of dissolution, transformation and crystallization of 2MgO · 2B2O3 · MgCl2 · 14H2O in water at 30℃ have been suggested.
出处
《无机化学学报》
SCIE
CAS
CSCD
北大核心
1993年第3期279-285,共7页
Chinese Journal of Inorganic Chemistry
基金
国家自然科学基金资助课题
关键词
盐卤硼酸盐
氯柱硼镁石
salt lake brine, chloropinnoitc, dissolution, transformation