摘要
一般条件下,碳酸氢钠与氢氧化钙以1:1(摩尔比)苛化。灰碱比低于0.5时,苛化液中没有大量OH^-生成,可认为反应先生成CO_3^(2-),再苛化成氢氧化钠。只在高温和高浓度时才有少量碳酸氲钠分解反应发生。苛化时随碳酸氢钠初始浓度增大,平衡苛化率下降。温度对平衡苛化率有影响,但不显著。温度可显著影响苛化速率,90℃反应两小时已趋近平衡。宏观动力学测定表明,反应属于二级,活化能不失,相当于扩散控制或控散—反应控制。
Under ordinary conditions, the mole ratio for causticizing sodium bicarbonate with calcium hydroxide is 1 : 1. As lime-bicarbonate ratio below 0.5, there is no abudant OH^- in the causticized solution. It is considered the reaction forms CO_3~2^- at first, then causticizes into caustic soda. Even during high temperature and concentration, bicarbonate only decomposes with small amount. The equilibrium conversion decreases as the initial concentration of bicarbonate increases. The temperature does not influence the equilibrium significantly, but increases the reaction rate, as the equilibrium will be approached during causticizing 2h at 90℃. Study of macrokinetics reveals that the reaction is of second order, activation energy is only 10.5 kJ/mol, so that diffusion or diffusion-transition stage may be the controlling step.
出处
《福建师范大学学报（自然科学版）》
CAS
CSCD
1992年第3期51-58,共8页
Journal of Fujian Normal University：Natural Science Edition
关键词
碳酸氢钠
苛化
苛性钠
碳酸钙
sodium bicarbonate, causticizing, caustic soda, calcium carbonate
