Experimental Study On Extraction Of Heavy Metal Ions By Microemulsion And Its Application In Centrifuge Extraction

Heavy metal wastewater pollution is one of the environmental problems,which needs to be solved urgently.As a commonly used method,solvent extraction has many advantages,such as convenient and high efficiency.However,there are many disadvantages,such as large dosage,poor stability and further pollution.As a separation medium,microemulsion has attracted many attentions in the fields of extraction and separation because of the excellent properties:the nanometer-sized spherical bicontinuous structure,the rapid coalescence and the structure of reseparation dynamics and the enhanced solubilization capacity.In this paper,we used sodium laurate and sodium oleate(surfactant),n-amyl alcohol(cosurfactant),n-heptane(oil phase),NaCl solution to prepare two kinds of thermodynamically stable W/O microemulsions.The dilution method and conductivity method were used to study the microstructure of microemulsion systems,which showed that increasing the NaCl solution concentraction appropriately is good to the stability of W/O microemulsion.The extraction mechanism of cobalt extraction was investigated by slope method:Co2+ was found to be extracted into the microemulsion phase due to the compound formation of[CoCl]+[R11COO]-;PH in the range of 2-6.5,R=9,t=8min,T=298.15K,under these conditions,the best extraction efficiency of cobalt was 98.9%.For cobalt and manganese wastewater,the extraction effects of sodium laurate microemulsion and sodium oleate microemulsion were compared.Based on this,combining the microemulsion extraction and centrifugal extraction technology,we built a centrifugal extraction device,which achieved the continuous and efficient treatment of cobalt and manganese wastewater.When the flow rate K was 1/5-5,the centrifuge extraction speed was 852-1988r/min,there is almost no two-phase entrainment phenomenon in the experiments;the highest extraction efficiency of cobalt and manganese was got when the centrifuge extraction speed was 1988r/min and the flow ratio was 1/5,was 99.98%and 99.12%respectively.The results of this study provided theoretical guidance for the application of industrialization,and microemulsion extraction would have good application prospects as a new technology.