扩散渗析法回收盐酸酸洗废水中的盐酸

为了从盐酸酸洗废水中回收盐酸,在静态扩散条件下采用模拟废水分别测定了HCl、FeCl_2在不同阴离子交换膜中的渗析速率以考察膜的分离性能,进而采用实际废水考察动态扩散时流量、流量比对回收率及回收酸浓度的影响.结果表明,用3362膜与DF120膜时,HCl的平均渗析速率分别为2.44×10~(-3) m/h和5.46×10~(-3) m/h,FeCl_2的平均渗析速率分别为1.49×10~(-4) m/h和2.67×10~(-4) m/h,酸盐分离系数可分别达到16.4和23.7.水酸流量比维持在1左右,流量维持在0.35 L/h的条件下,回收酸中盐酸浓度分别为0.26 mol/L和0.43 mol/L,FeCl_2浓度均小于0.002 mol/L,酸回收率分别为40%和65%,FeCl_2透过率均小于8%.

Recovery of hydrochloric acid from the HCl pickling sewage by diffusion dialysis

The present paper is to introduce our renovated method for recovery of hydrochloric acid from the HCL pickling sewage by diffusion dialysis. For the given purpose, we have, first of all, measured the dialysis velocity of HCl and FeCl_2 in different anion exchange membranes by using a simulated system under the static condition, and, then analyzed the effect of the operating parameters of dynamic state diffusion dialysis on the acid recovery rate and the acid concentration in diffusate through different anion exchange membranes. The parameters we have studied include the flowing rate of the feed as well as the flowing rate ratio of the water to the feed. It was found that the used 3362 and DF120 membranes had a good separation property. When the test is done with membranes 3362 and DF120, it was found that the dialysis velocity of HCl was about 2.44×10~(-3) m/h and 5.46×10~(-4) m/h respectively, whereas the dialysis velocity of FeCl_2 was 1.49×10~(-4) m/h and 2.67×10~(-4) m/h respectively, with the separation factor between HCl and FeCl_2 being 16.4 and 23.6, respectively. It was also found that the higher the acid concentration in the feed, the lower the dialysis velocity of HCl and FeCl_2 in the membrane, and the higher the FeCl_2 concentration in the feed, the higher the dialysis velocity of HCl, but the lower the dialysis velocity of FeCl_2 in the membrane. On the other hand, in the dynamic system, the hydrochloric acid recovery rate could reach 40% and 65%, respectively, with a FeCl_2 leakage rate less than 8%. On the condition that the flowing rate ratio of water to the feed was around 1, the flowing rate would be 0.35 L/h, at the acid concentration of 0.26 mol/L and 0.43 mol/L respectively and that of FeCl_2 less than 0.002 mol/L in the diffusate. The results of our investigation have also revealed that the flowing rate of feed, the flowing rate ratio of water to the feed serve as important factors in the diffusion dialysis operation. Our findings also indicate that the higher the flowing rate of the feed, the lower of the hydrochloric acid recovery rate, whereas the recovered HCl concentration in the diffusate would drop significantly with the change of the flowing rate ratio from 0.4 to 1.