铝合金铬酸阳极氧化废水中六价铬萃取法回收利用可行性

Reuse Feasibility of Cr(Ⅵ) Recovery by Extraction from Aluminum Alloy Chromic Acid Anodizing Wastewater

文中以铝合金铬酸阳极氧化废水为研究对象,探讨了萃取法回收高浓度Cr(Ⅵ)的可行性。探究不同萃取剂、萃取浓度、萃取时间、相比以及废水初始pH对萃取效果的影响,并优化工艺参数。根据萃取效果,四丁基溴化铵(TBAB)对Cr(Ⅵ)萃取效果最好。萃取剂摩尔浓度为0.6 mol/L、萃取时间为5 min、V_(废水)/V_(萃取剂)为1.0时,TBAB对Cr(Ⅵ)的萃取率达到96.34%。同时,pH越低萃取效果越好。因此,萃取法适合于本研究中低pH、高浓度的铬酸废水。反萃取过程中,NaOH的反萃效果最好,NaOH摩尔浓度为4 mol/L时,对Cr(Ⅵ)的反萃率达到99.51%,反萃取后水相中Cr (Ⅵ)质量浓度达到21.73 g/L,可以进行回收利用。

The feasibility of high concentration Cr(Ⅵ) reuse by extraction method from chromic acid aluminum anodizing wastewater is introduced. The effects of different extractants, extractant concentration, time, phase ratio and initial pH value of wastewater on extraction efficiency were studied in detail to optimize operational parameters. Tetrabutylammonium bromide(TBAB) performed best in extracting Cr(Ⅵ) based on extraction efficiency. 96. 34% of Cr(Ⅵ) was extracted at optimal conditions: extractant concentration was 0. 6 mol/L, time was 5 min and V_(wastewater)/V_(extractant) was 1. 0. At the same time, low pH was conducive to extraction. Therefore, extraction was suitable for the chromic acid-rich, low pH wastewater in this study. Na OH was found to have the highest back extraction efficiency which reached 99. 51% when NaOH was set at 4 mol/L. Cr(Ⅵ) in aqueous phase reached as high as 21. 73 g/L and could be reused.