电沉积处理含镉废水的性能研究

PERFORMANCE OF CADMIUM WASTEWATER TREATMENT BY ELECTRODEPOSITION

电沉积含镉废水考察溶液的不同初始p H、镉的不同初始浓度、电流密度及金属配合物对电沉积效果的影响,利用SEM和XRD对沉积物的表面形貌和物相成分进行分析,研究沉积物金属的存在形式。实验结果表明,p H在1.5~3.5时,溶液中镉的去除效果达到99.3%;一级动力学常数随着初始镉溶液浓度增加而变大;当电流密度为4.46 m A/cm2进行90 min电沉积时反应速率较快且沉积量最大;氨水与镉形成的配合物可以促进电沉积镉的反应速率;对电沉积后的沉积物进行扫描电镜(SEM)和X-射线衍射(XRD)测试。SEM表明,沉积物呈现树枝状的纳米结构。XRD表明,沉积物主要成分为氢氧化镉和镉。

The effects of initial p H,initial concentration,current density and complexing agents on the recovery of cadmium were examined. The surface morphology of the deposition was tested by SEM. The phase analyses were obtained by X-ray diffractometer. Experimental results showed that cadmium removal efficiency in the solution reached 99. 3% as the p H 1. 5 ~3. 5. The kinetics constants went up with the increase of initial cadmium concentration. The largest deposited mass was produced at the deposition time of 90 min and the suitable current density of 4. 46 m A / cm2. Ammonia and cadmium forming complexes could promote the reaction rate of cadmium electrodeposition. Sediments of electrodeposition were tested by scanning electron microscopy( SEM) and X-ray diffraction( XRD). SEM showed that the sediments of dendritic nanostructures. XRD showed that cadmium and cadmium hydroxide were existed mainly.