Treatment And Reutilization Of H-acid Wastewater Of High Concentration By Complex Extraction

With the rapid development of China's national economy,the textile industry as the traditional pillar industry has entered a stage of rapid development,and led the important naphthalene dyes intermediate of H-acid production enterprises in the rapid development.However,in the process of production of H-acid has produced a large number of wastewater with high concentrations,high salinity and it is difficult to biodegrade,If we emissions the wastewater directly with nothing treatment that will cause serious pollution to the environment and extremely harmful to the human body.So it has important academic significance and application value of the treatment and research of H-acid wastewater.In this paper,the high concentration of H acid wastewater was treated by complex extraction method,and the cross-flow extraction process system was established.The wastewater of H-acid with initial COD of 35000 mg/L and p H of 2.3 was studied by crossflow extraction.The extraction system,the extraction time,the extraction stages,the extractant concentration,the phase ratio and the extraction temperature on the removal efficiency of COD are investigated.The best extraction system are as follows: TOA as extractant,kerosene as diluent and octanol as cosolvent.Under the TOA/kerosene/octanol extraction system,the optimum process parameters were the volume ratio of TOA and kerosene of 1/4,phase ratio(A/O)of 5/1,p H of 2.3,extraction time of 30 minutes.The overall CODcr removal rate can reach 83.4% by the two-stage extraction.The parameters of the cross-flow extraction were established by response surface analysis method,the variance analysis and response surface analysis were used to verify that the optimal parameters were reliable and the extraction time,extractant concentration and the phase ratio on the removal efficiency of COD were as follows: extraction time>extractant concentration>the phase ratio.The countercurrent complexation extraction technology was established by using the mixed clarification extraction tank and the countercurrent extraction process system was established.The H-acid wastewater with the initial COD value of 7000 mg/L was studied.The hydraulic retention time,the extractant concentration and the phase ratio on the removal efficiency of COD are investigated.the optimum process parameters were hydraulic retention time of 8 minutes,the volume ratio of TOA and kerosene of 1/6 and phase ratio(A/O)of 5/1.The overall CODcr removal rate can reach 77.5% by the countercurrent extraction.The parameters of the countercurrent extraction were established by response surface analysis method,the variance analysis and response surface analysis were used to verify that the optimal parameters were reliable and the hydraulic retention time,extractant concentration and the phase ratio on the removal efficiency of COD were as follows: hydraulic retention time>extractant concentration>the phase ratio.The regeneration and extraction system of extraction phase and raffinate phase were established.For the phasee of extraction,12.5% Na OH solution was used to backextraction on the extraction phase.Using the ratio of oil-base was 2/1 and with six times of repeated regenerative experiments that the recoveries of the extractant was 89%-91%,and the removal rate of COD was 42.8%.The renewable extractant can be recycled.For the phase of raffinate,we can recover the solid of sulfate after crystallization by air-dried,the purity of Na2SO4 is 100%.The mechanism of extraction of H-acid by TOA with the fourier transform infrared spectroscopy(FTIR)was studied.The results showed that the extraction of H-acid by TOA was an endothermic reaction.In the form of ion salt,one TOA molecule was associated with one H-acid molecule and the composition consisted of 1: 1.