Abstract:

Industrial production processes such as electroplating, metal processing, fur tanning, metal smelting and offset printing produce high concentrations of chromium-containing wastewater. In order to solve the difficult treatment problem of high concentration chromium-containing wastewater, the effects of type of reducing agent, reaction time, dosage, pH and initial concentration of chromium-containing wastewater on the reduction performance of Cr(Ⅵ) were studied by indoor static experiment method. The reduction kinetic equation was established, and the treatment experiment of actual chromium-containing wastewater was carried out. The experimental results showed that calcium polysulfide had better reducing properties than other sulfur reducing agents such as Na₂SO₃ and Na₂S₂O₄. The optimum dosage of calcium polysulfide was 1.75 times of the theoretical dosage, the best reaction time was 90 min, and the treatment effect under the condition of acid environment was better. X-rays diffraction(XRD) showed that the reduction product of Cr(Ⅵ) by calcium polysulfide contained Cr(OH)₃ and elementary substance S with good crystalline. The reduction of Cr(Ⅵ) by calcium polysulfide conformed to the second-order reaction kinetics. The actual wastewater containing 105.42 mg/L Cr(Ⅵ) was treated well, with a high Cr(Ⅵ) removal rate of 95.16% at 90 min.

Key words: calcium polysulfide, chromium-containing wastewater, Cr(Ⅵ), reduction kinetics

摘要：

电镀、金属加工、鞣制毛皮、冶炼金属、胶版印刷等工业生产过程中，会产生较高浓度的含铬废水。为解决高浓度含铬废水难处理问题，采用室内静态实验方法，研究了还原剂种类、反应时间、投加量、pH以及初始含铬废水浓度对Cr（Ⅵ）还原性能的影响，建立还原动力学方程，并进行了实际含铬废水处理实验。实验结果表明，多硫化钙（CaS_x）还原性优于Na₂SO₃、Na₂S₂O₄等其他硫系还原剂；CaS_x最佳投药量为理论投加量的1.75倍，最佳反应时间为90 min，且偏酸性环境条件下处理效果更好；XRD分析表明，CaS_x还原Cr（Ⅵ）的产物中含有结晶状态良好的Cr（OH）₃沉淀与S单质；CaS_x对Cr（Ⅵ）的还原过程符合二级反应动力学模型。对含有105.42 mg/L Cr（Ⅵ）的实际含铬废水的处理效果良好，90 min时Cr（Ⅵ）的去除率高达95.16%。

关键词: 多硫化钙, 含铬废水, Cr（Ⅵ）, 还原动力学

CLC Number: 

• X703