Nanofiltration coupled with electrolytic oxidation in treating simulated dye wastewater

To investigate the effects of electrolytic oxidation on nanofiltration in treating dye waste water, we put a mesh catalytic electrode on the intercept side of the membrane and apply a voltage to realize the coupling of electrolytic oxidation and nanofiltration. The effects of the electroosmosis, electrophoresis and electrochemical oxidation on the flux were investigated. Experiments show that electroosmosis makes the flux increase linearly with the electric intensity. When there is only an electric filed in the coupling experiments, we get that, with the increase of the electric intensity the flux is accelerating until the electric intensity reach the critical value, after that the flux increase linearly with the electric intensity. With the current density increasing, the degraded organics and the bubbles generated increase, and so the thickness of the concentration polarization and gel layer is reduced in a certain degree. The flux increases with the decrease of the feed concentration in the coupling experiments. The trend that the flux increases with the pressure slows down. The flux increases to a certain value and then keeps constant with the increase of the cross flow velocity. The trend that the flux decreases with time slows down with the increase of the voltage, because of the electroosmosis, electrophoresis and electrochemical oxidation. And when the voltage increases to a certain degree, the flux keeps at a high level and changes less with time because the thickness of concentration polarization and gel layer is reduced to the minimum. (C) 2012 Elsevier B.V. All rights reserved.