Carbon cloth as an important electrode support for the high selective electrosorption of uranium from acidic uranium mine wastewater

An amidoxime modified carbon cloth electrode (CC-AO) was applied for uranium electrosorption at low pH value of 2. Experiments using other carbon-based electrodes were also carried out for comparison. The kinetics, isotherm, selectivity, reusability and power consumption during the uranyl ions (UO₂²⁺) electrosorption were studied in-depth. The effects of voltage and frequency on UO₂²⁺ selectivity among coexisting ions were investigated. The results showed that UO₂²⁺ (20 mg/L), removal by CC-AO was 94.3% at pH = 2 with a high electrosorption capacity of 989.5 mg/g (within 12.5 h). The electric field drove UO₂²⁺ to move to the cathode surface and produced UO₃·2H₂O on CC-AO. Under the optimal electric field (- 2.5 V, 800 Hz), CC-AO achieved the highest UO₂²⁺ selectivity in the simulated acidic uranium mine wastewater, and the frequency was the main factor. The CC-AO can be effectively used for seven UO₂²⁺ electrosorption-desorption cycles. Moreover, a new index of “unit power consumption for half amount uptake” (PC_1/2) was proposed to quantify the power consumption during UO₂²⁺ uptake by different electrodes. In electrosorption system, the available area of CC-AO is larger than that of CF-AO, so its electrosorption efficiency for UO₂²⁺ is much higher than the latter. The current CC-AO showed clear advantages in terms of electrochemical features, adsorption capacity, selectivity, and power consumption at such low pH condition, indicating an application potential for uranium recovery from acidic uranium mine wastewaters.