基于电容电极的耦合电化学法去除含盐重金属离子的机制

The pollution accidents of heavy metals wastewater have sounded the alarm for us once again with the rapid development of mining and metallurgy, electroplating, batteries and chemical industries. Generally, there are a variety of heavy metal ions and salinity in the heavy metals wastewater from actual industries. If the traditional methods involved chemical precipitation, iron carbon reaction, ion exchange and adsorption were adopted, the competitive effect and salting-in would affect their removal rate, and a huge amount of reagents and wastes would limit their application. Otherwise, the high salinity is not conducive to the operation of membrane separation and biological methods. The metal oxide electrode with high Faraday pseudocapacitance usually is used for supercapacitor. Accordingly, a coupled electrochemical process of capacitor electrode-EDI-crystallization fluidized bed is proposed for heavy metals salinity wastewater treatment in this project. The preparation method of titanium electrode doped metal oxide will be explored for high surface area, stable performance, good electrical conductivity and anti-pollution ability. The reaction mechanisms of Faraday pseudocapacitance will be researched between the prepared capacitance electrode and various kinds of metal ions. The deionization, concentrate and recovery mechanisms of coupled reactor will be studied and optimized for multiple metal ions. That will provide a theoretical basis for the efficient treatment technology with low energy and anti-pollution according to heavy metals salinity wastewater, and provide a new idea for the removal as well as recovery of heavy metal ions and salt ions.

随着矿冶、电镀、蓄电池和化工等工业的快速发展，重金属废水污染事故又一次为我们敲响了警钟。实际工业重金属废水中通常含有多种重金属离子及一定的盐度，如果采用传统的化学沉淀、铁碳法、离子交换和吸附法处理，不仅竞争作用和盐溶效应会影响其去除效果，且庞大的药剂量和废渣量也限制了其应用。此外，较高的盐度也不利于膜分离和生物法的应用。 用于超级电容器的金属氧化物电极具备高法拉第准电容，据此，本项目提出采用电容电极-EDI-结晶流化床耦合电化学法处理含盐重金属废水，探索表面积大、性能稳定、导电性好、抗污染的掺杂金属氧化物钛电极的制备方法，并研究电容电极与多种金属离子的法拉第准电容反应机制；针对多种金属离子，研究耦合反应器的去离子及浓缩回收机制，并进行优化，为研究高效低耗抗污染的含盐重金属废水处理技术提供理论依据，为同时高效去除并回收多种金属离子提供新思路。

实际工业废水通常含有机物、重金属离子和盐类，由于盐溶效应和竞争吸附作用，使得有机物和重金属的去除效果受到不利影响。以石化反渗透浓水为研究对象，采用逆流二级吸附工艺在节约37%活性炭的基础上，使淡水总回收率由70%提高至91%，较准确地预测了出水水质，并形成了逆流吸附-反渗透-电氧化-电脱盐的零排放组合工艺。.提出电容去离子（CDI）-电去离子（EDI）装置，利用电吸附-离子交换-电迁移多重作用去除废水中的阴阳离子，显著提升了去离子效果，并减少了结垢现象。CDI-EDI装置通过短时间水解电流再生树脂，反向低电流脱附再生电容电极，再生液和浓缩液循环使用，高效低耗，操作简单，可自动控制。处理50 mg/L的铜离子模拟废水，阳室和阴室出水平均去除率分别为96.4%和87.4%，稳定性好。处理TDS为5.67 g/L，pH为3.1，镍离子浓度389.4 mg/L，氨氮503.5 mg/L的实际电镀废水，经过强化沉淀-微滤预处理后，进入CDI-EDI装置，阳室和阴室出水镍离子的平均浓度分别为1.61 mg/L和2.01 mg/L。.当废水含盐量＞5%，重金属离子浓度亦较高时，需先做沉淀和脱盐预处理，以减少CDI-EDI装置的负荷，从而达到较好的去离子效果。针对含盐量19%的实际锂电池三元电极前驱体废液，提出强化二级沉淀-微滤-诱导结晶预处理工艺，经过NaOH强化一沉实验，以及Na2S强化二沉实验，钴镍离子分别由15 mg/L和262 mg/L降至0.499 mg/L和0.865 mg/L，出水在3℃下用Na2SO4诱导结晶脱盐，再进入CDI-EDI装置处理至达标排放。.本项目提出的零排放组合工艺、CDI-EDI装置和强化沉淀-微滤工艺为研究高效低耗抗污染的含盐重金属废水处理技术提供了理论依据，为同时高效去除并回收重金属离子提供了新思路。.