萃取法处理DSD酸氧化废水

以二甘醇单丁醚-二甘醇单乙醚-对二甲苯体系为萃取剂,0.1 mol/L的Na OH溶液为反萃取剂,采用三级萃取-反萃取法处理4,4’-二氨基二苯乙烯-2,2’-二磺酸氧化废水,考察了萃取和反萃取的影响因素,并对废水中的可用有机资源进行了回收。实验结果表明:在V(二甘醇单丁醚)∶V(二甘醇单乙醚)=1∶3、V(醇醚)∶V(废水)=2∶5、V(对二甲苯)∶V(废水)=1∶5的最佳萃取条件下,经三级萃取工艺处理后,平均COD去除率达92.0%、平均脱色率达96.4%、BOD5/COD0.3,可生化性明显增强;最佳反萃取条件为V(Na OH溶液)∶V(有机相)=13∶24、反萃取温度60℃;平均总硝基化合物回收率达88.9%,平均萃取剂回收率达96.7%,回收的萃取剂可循环使用。该工艺对废水处理的综合成本约为700~1 000元/t。

Treatment of Oxidation Wastewater in DSD Acid Production by Extraction Method

The oxidation wastewater in production of 4,4’-diaminostilbene-2,2’-disulfonic acid （DSD acid） was treated by three-stage extraction-back-extraction process,using diethylene glycol monobutyl ether-diethylene glycol monoethyl ether-dimethylbenzene as extractant and 0.1 mol/L NaOH solution as back-extractant. The factors affecting extraction and back-extraction were studied and valuable organic resources were recovered from the wastewater. The experimental results show that：Under the best extraction conditions of V（diethylene glycol monobutyl ether）∶V（diethylene glycol monoethyl ether）=1∶3,V（alcohol ether）∶V（wastewater）=2∶5,V（dimethylbenzene）∶V（wastewater）=1∶5 and extraction time 3,the average COD removal rate is 92.0%,the average decolorization rate is 96.4%,BOD₅/COD>0.3,which indicates that the biodegradability of the wastewater is improved obviously;The best back-extractant conditions are V（NaOH solution）∶V（organic phase）=13∶24 and back-extractant temperature 60 ℃;The recovery rates of total nitro-compounds and extractant are 88.9% and 96.7% respectively,and the recovered extractant can be reused. The total cost of the wastewater treatment process is 700-1 000 Yuan/t approximately.