A two-step strategy for high-efficiency fluorescent dye removal from wastewater

Abstract

Conventional circulating activated sludge techniques (CASS) are time consuming (72 h) and energy intensive, all of which greatly limits their use. Although advanced oxidation techniques (e.g., photocatalysis, photoelectrocatalysis UV/•OH, and Electro-Fenton) can reduce the treatment time by several hours, the slow generation and fast coupling of electron and hole make the low degradation efficiency. In this work, an intact route using a two-step strategy is developed to eliminate organic dyes from wastewater in only a few minutes. The electron and hole exhibit “fast generation and slow coupling” by using the new technique via electrolytic discharge plasma (EDP) combined with a core-shell structure Au@SiO2 nanocatalyst for [Rhodamine (RhB)/Eosin yellowish (EY)] dyes degradation in wastewater. Results demonstrate that the synergy of EDP and Au@SiO2 nanocatalyst enhances degradation kinetics, and it is effective in degrading different concentrations of RhB and EY dyes in the range of 50–1.5 mg/L. Then, the Au@SiO2 nanocatalyst (over 99%) and carbon impurities are filtered by a porous nanocomposite ultrafiltration membrane. Favorable contributions of the two-step strategy are further ascertained based on chemical oxygen demand (COD) and relative removal efficiency. This two-step strategy provides an unprecedented rapid approach for industrial wastewater treatment.