双极性膜电渗析法回收钨酸钠溶液中的游离氢氧化钠

RECOVERY OF SODIUM HYDROXIE FROM SODIUM TUNGSTATE SOLUTION BY BIPOLAR MEMBRANE

以游离碱,氢氧化钠的迁移率、电能消耗、电流效率、渗析槽电压、温度等经济、技术指标为目标函数,对制约双极性离子交换膜电渗析的重要变量进行了试验,其中包括:电流密度和碱液初始浓度等。结果表明,电能消耗(E/kWh/T)与电流效率(η/%),彼此成反比关系;游离碱氢氧化钠的初始浓度与电流密度是制约电能消耗与电流效率的主要参数;提高游离碱初始浓度,不仅有利于提高电流效率,也有利于减少电能消耗;但是,当游离碱初始浓度增加到2.0 mol/L时,开始出现拐点,此后,电流效率略有下降,然而,电能消耗维持恒定。对于6级并联渗析槽而言,如果电流密度与游离碱初始浓度分别设定为:电流密度i=73.3 mA/cm2、游离碱初始浓度C=2.0～2.5 mol/L,那么电能消耗低于2 500～3 000 kWh/t氢氧化钠溶液。

The effects for eleetrodialysis with bipolar membrane of such technological parameters as operative elec- tric current density , concentration of sodium hydroxide in an original solution and recovering solution on the techno- logical index of electric energy consumption , electric current efficiency and removal ratio of sodium hydroxide was tested by bipolar and cathodic ion membrane. The results have proved that the relationship between the electric en- ergy consumption and electric current efficiency is the reverse. The most important parameters effecting the electric energy consumption and electric current efficiency were the concentration of sodium hydroxide in the original solu- tion and electric current density. As the concentration of sodium hydroxide in original solution is 2.0 mob/L, turn- ing point was revealed. If the original concentration of raw material solution was 2.0 -2.5mol/L, the electric cur- rent density was 73.3 mA/cm2, the electric energy consumption was within the range of 2 500 - 3 000 kWh/t sodi- um hydroxide solution.