LAUSR

Abstract Microfluidic solvent extraction of copper from sulfate solution containing Cu2+, Fe3+ and Zn2+ using DZ988N (a mixture of equal volumes of 5-nonylsalicylaldoxime and 2-hydroxy-5-nonyl-acetophenoneoxime) has been conducted for the first time using an interdigital micromixer with 30 channels of 40 μm width. Conventional batch extractions were carried out in parallel for comparison. Effects of the initial pH value of the aqueous phase, concentration of the extractant, and flow rate on the extraction efficiency of Cu2+ have been studied including determination of separation factors (βCu/Fe and βCu/Zn). According to single factor experiments, the optimal extraction parameters were an initial pH value of 1.96, extractant concentration of 15% and an aqueous or organic phase flow rate of 15 mL/min. Under these preferred conditions, copper extraction of 84.05% was achieved with βCu/Fe and βCu/Zn values of 644 and 7417, respectively. Compared with batch extraction, micromixer extraction exhibits faster extraction times, higher extraction efficiency of copper and an improved separation factor between copper and the impurity elements of iron and zinc. In addition, copper extraction isotherms (McCabe Thiele) from copper-only solutions for microfluidic extraction and batch extraction were constructed to determine the number of stages. The results show that the extraction efficiency with microfluidic extraction was better than that of traditional batch extraction. In the microfluidic extraction process, as much as 99% extraction efficiency was achieved in a single stage for the copper-only solution. However, in the corresponding batch extraction process, to get the same extraction efficiency, two stages of extraction were needed.