双极膜电渗析资源化硝酸钠制酸碱

Preparation of acid-base by bipolar membrane electrodialysis using NaNO_(3)as resource

工业生产中产生的含有NaNO_(3)的高盐废水是一种可回收再利用的资源,通过双极膜电渗析(BMED)技术可制备出相应的酸和碱,对高盐废水的资源化利用具有重要的意义。采用三隔室双极膜电渗析膜堆,以NaNO_(3)溶液模拟高盐废水制备HNO_(3)和NaOH。选取能耗、电流效率、转化率作为评价指标,探究电流密度、原料液浓度、极液种类及浓度、酸碱室初始浓度对BMED制酸碱过程的影响。结果表明:随着电流密度的增大,盐转化率提高,能耗增加;随着原料液浓度的增大,电流效率增加,能耗降低,原料液浓度过高会导致电流效率明显降低;极液以3%(质量分数)的NaOH最宜;酸碱室初始浓度的增加可提高盐转化率,降低能耗。综合各因素最优参数进行实验,在电压为35 V、电流密度为700 A/m^(2)、酸碱室初始浓度为0.05 mol/L、原料液为12%(质量分数)的硝酸钠、极液为3%(质量分数)的NaOH的条件下,制得的碱浓度为2.227 mol/L,盐转化率可达93.42%,电流效率为60.83%,能耗为3.23 kW·h/kg。研究结果可为工业生产中NaNO_(3)高盐废水的资源化利用提供参考。

In industrial production activities,highsalt wastewater containing NaNO_(3) is usually produced,which is a recyclable resource.The corresponding acids and bases of high salt wastewater can be prepared by bipolar membrane electrodialysis(BMED).The technique is of great significance for the resource utilization of highsalt wastewater.In this experiment,a threecompartment bipolar membrane electrodialysis membrane stack configuration was used to simulate highsalt wastewater with NaNO_(3) solution to prepare HNO_(3) and NaOH.The experiment used energy consumption,current efficiency,and conversion rate as evaluation indexes.The effects of current density,the concentration of raw material solution,type and concentration of polar liquid,and initial concentration of acidbase chamber solution,on the preparation of acidbase by BMED were investigated.The results showed that when the current density was increased,an increase in the salt conversion rate and energy consumption could be observed.An increase in current efficiency and a decrease in energy consumption could be found as the concentration of raw material solution was increased.However,the concentration of raw material solution was too high,which would cause the current efficiency to decrease obviously.3%NaOH was best for polar solution.When the initial concentration of the acidbase chamber was increased,an increase in the salt conversion rate and a decrease in energy consumption could be observed.The parameters were optimized as follows:the operating voltage was 35 V,the operating current density was 700 A/m^(2),the initial concentration of the acidbase chamber was 0.05 mol/L,the raw material liquid was 12%sodium nitrate,and the polar liquid was 3%NaOH.Under these conditions,the concentration of base was 2.227 mol/L,the salt conversion rate was up to 93.42%,the current efficiency was 60.83%,and energy consumption was 3.23 kW·h/kg.The research results could provide a reference for the resource utilization of NaNO_(3) high salt wastewater in industrial production.