离子交换耦合膜分离技术回用电镀废水中Cr(Ⅵ)技术研究

On the splitting and recycled use of Cr( Ⅵ)in electroplating sewage by the ion exchange of the coupling membrane splitting technology

为实现电镀废水中6价铬离子(Cr(Ⅵ))回用,将纳滤技术与离子交换技术耦合,建立了1 m3/h中试试验装置。含Cr(Ⅵ)废水经离子交换纤维吸附处理,出水Cr(Ⅵ)质量浓度≤0.08 mg/L,可达标排放;将离子交换纤维吸附饱和后再生,获得5 000 mg/L以上Cr(Ⅵ)浓缩液,同时含有Cl-。采用纳滤膜处理该浓缩液,将Cr(Ⅵ)与Cl-分离。对比研究了运行压力和离子质量浓度对分离效果的影响,由此筛选较适宜膜产品。结果表明:进水Cr(Ⅵ)质量浓度为3 680mg/L,Cl-质量浓度为16 049 mg/L,运行压力为0.7 MPa,Cr(Ⅵ)截留率为80%,Cl-完全透过;溶液p H=8和p H=11时纳滤膜对Cr(Ⅵ)、Cl-分离效果无显著差异;经过60 d试验纳滤膜的脱盐性能无衰减。将离子交换与纳滤技术耦合,连续运行,能获得Cr(Ⅵ)质量浓度为3 200 mg/L、Cl-质量浓度为20 mg/L的浓缩液。研究表明,集成工艺整体可行,具有潜在应用价值。

This study is oriented to introduce its investigation of the method for integrated use of the ion-exchange and nano-filtration membrane technology for splitting and reuse of Cr（ Ⅵ） from the chrome-plating sewage. It is just for this end that we have established the 1 m3/ h pilot experimental device,by which we have made an exploration of the adsorption and regeneration performance of the ion exchange fiber. The results of our investigation have shown that the Cr（ Ⅵ） concentration in effluent is equal to less than 0. 08 mg / L,which is in accord with the national standard GB 8978—1996. Ion exchange fiber would be regenerated when it is saturated. What is more,the Cr（ Ⅵ） concentration should be much more than 5 000 mg / L in the regenerated liquid,in which there exist large amounts of chlorine ions. And,then,it would be possible to use the nanofiltration membrane for separating Cr（ Ⅵ） ion and chlorine ions in the regenerated liquid. Besides,we have also studied the separation performance of the three kinds of nanofiltration membrane with the effect of the initial Cr（ VI） concentration and operating pressure being looked through. In so doing,we have rightly chosen the appropriate nanofiltration membrane. When the Cr（ VI） ions account for 3680 mg / L,with the Cl-16 049 mg / L in the raw influent,the rejection rate of Cr（ Ⅵ） ions has been found to reach 80% at 0. 7MPa,whereas the chloride ions were found to be able to penetrate the membrane freely. Furthermore,we have also analyzed the effect of p H on the separation of Cr（ VI） and chloride ion,on the condition that there doesn＇t seem to find any notable difference at p H = 8 and p H = 11. In addition,no desalination performance of nanofiltration membrane has been found decreasing 60 days later.And,finally,we have managed to apply the integration system to the separation and reuse of Cr（ VI）. Thus,it can be concluded that it is possible for us to prepare quite highly concentrated solution,in which Cr（ Ⅵ） ions can be made to reach 3 200 mg / L,whereas Cl-can be made to reach 20 mg / L. Thus,the integration technology proves to be feasible and promising for separation and reuse of Cr（ Ⅵ）.