Electro-catalytic membrane anode for dye removal from wastewater

Abstract

A TiO2 loaded carbon membrane termed, “TiO2/carbon electro-catalytic membrane” as anode (dead-end mode) and a stainless-steel mesh as cathode articulated an electrocatalytic membrane reactor (ECMR) to treat methylene blue (C16H18ClN3S.3H2O) wastewater. TiO2/carbon membrane was characterized by field emission scanning electron microscope, high resolution transmission electron microscope and atomic force microscope. Elemental analysis was done by energy dispersive X-ray spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy to ascertain TiO2 loading on the carbon membrane. A synthetic 200 ppm methylene blue (MB) solution with electrolyte (Na2SO4) of 15 g/L concentration was used as the feed. Novel electro-desorption effect was discovered in a fully adsorbed membrane. Another novel finding regarding the ECMR was the acidic pH of permeate. When ECMR applied voltage was set to 2.5 V and current to 8 mA, the current density was calculated as 0.56 mA/cm2. While the porosity of the carbon membrane was 32.6 % and the flow rate was set to 200 μL/min, the residence time was calculated as 5.74 min. The result showed that the chemical oxygen demand (COD) removal rate of 83.65 % and color removal rate of 99.94 % were obtained. Electric consumption of the ECMR setup for MB solution was 5.87 kW h/Kg COD. The difference between the effect of adsorption and electro-catalysis was also calculated. The degradation mechanism of MB was proposed by using high performance liquid chromatography – mass spectroscopy. The excellent performance of ECMR was attributed to the synergetic effect of electro-catalytic oxidation and membrane separation which increases its economic feasibility by reducing the costs associated with cleaning the membrane at industrial scale. The ECMR proved a good stability as well.