An oblique rotating barrel electrochemical reactor for removal of copper ions from wastewater

An experimental study was performed using an oblique rotating barrel cathode to recover copper from a simulated wastewater, which initially contained 100 parts per million (ppm) of cupric ions. The barrel was a perforated cylindrical polypropylene basket having several axial and circumferential fins on its exterior surface. It was partially filled with copper Raschig rings and was partially submerged in the wastewater at a tilted angle from the horizontal position. During the operation, the barrel was slowly rotating about its axis and the copper rings were made as the cathode by connecting them to a d.c. power supply through a dangler contact. The movement of exterior fins and tumbling motion of copper rings provided a high mass transfer rate and a large cathode area for copper electrodeposition reaction. The cupric ion concentration in the wastewater was reduced to less than 1.0 ppm, permitting discharge of the treated wastewater to the drain system. With an operating cell voltage of 2.5-5.0 V, the overall cathode current efficiency was 53-20%, and the electric energy requirement was 4 to 21 kWh per kilogram of copper recovered from the wastewater. An apparent first order reaction rate constant for copper electrodeposition reaction on the Raschig rings was measured as a function of process variables including cell voltage, barrel rotational speed, percentage barrel loading, barrel tilt angle and percent barrel immersion.