氢氧化镉溶出特性及毒性浸出实验研究

Experimental Study on Leaching Characteristics and Toxicity of Cadmium Hydroxide

实验采用硫酸镉与氢氧化钠人工合成氢氧化镉摸拟实际氢氧化镉,X射线衍射分析确定氢氧化镉在20~100℃下干燥没有发生晶型转化,为同一稳定晶型。通过考察温度、酸度、搅拌速度对氢氧化镉溶出的影响及氢氧化镉溶出过程的镉水解,得出了氢氧化镉溶出的基本规律,实验结果表明:当搅拌速率为400 r/min时基本已经消除了外扩散对镉溶出浓度影响;溶出浓度随pH的降低而升高,随温度的升高而升高;氢氧化镉溶出过程中发生镉水解,通入CO_(2)能促进镉的水解。根据相关标准进行毒性浸出试验,浸出毒性为0.9 ug/mL。研究结果对含镉废渣稳定化/固化设计、环境影响评价及其污染防治有一定的参考价值。

The experiment used cadmium sulfate and sodium hydroxide synthetic cadmium hydroxide to simulate the actual cadmium hydroxide.X-ray diffraction analysis determined that cadmium hydroxide in 20~100 degrees C drying didn’t occur crystal transformation.To further confirmthe basic law of the dissolution of cadmium hydroxide,we investigated the effects of temperature,acidity and stirring speed on the dissolution of cadmium hydroxide and the hydrolysis of cadmium in the dissolution process.The experimental results showed that the effect of external diffusion on cadmium hydroxide's dissolution concentration was basically eliminated when the stirring speed was 400 R/min.The dissolution concentration increased with the decrease of pH and the increase of temperature.The hydrolysis of cadmium occurs during the extraction process,which can be promoted by adding carbon dioxide.The toxicity leaching test was carried out according to relevant standards,and the leaching toxicity was 0.9 ug/mL.The research results shed light on the design of stabilization and solidification of cadmium waste residue and have great promise in environmental impact assessment and pollution control.