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.
Highlights
The amount of fresh water on Earth is limited under constant pressure
Water quality can be compromised by the presence of pathogens, pesticides, PPCPs, heavy metals,[1,2,3] which causes severe environmental problems due to complex chemical composition, toxicity, strong color, high chemical oxygen demand (COD), and low biodegradability.[4,5,6,7,8,9,10,11,12,13,14,15,16]
Extensive studies have focused on the development of advanced oxidation techniques for effective and efficient remediation of dyestuffs in wastewater, such as TiO2 photocatalysis,[14] photoelectrocatalysis,[15] UV/HO,[16] and Electro-Fenton.[17]
Summary
The amount of fresh water on Earth is limited under constant pressure. Preserving the quality of fresh water is important for drinking water supply, food production, and recreational water.Water quality can be compromised by the presence of pathogens, pesticides, PPCPs, heavy metals,[1,2,3] which causes severe environmental problems due to complex chemical composition, toxicity, strong color, high chemical oxygen demand (COD), and low biodegradability.[4,5,6,7,8,9,10,11,12,13,14,15,16] Many toxic and persistent substances, such as polycyclic aromatic hydrocarbons in dyestuffs wastewater, can weaken the ecosystem and place many species at risk of extinction. 1234567890():,; Fig. 2 a Current–voltage characteristics during the EDP process in the K2S2O8 electrolyte using simulated organic wastewaters; and b suitable parameters of EDP for dye degradation at a pulsed frequency of 4000 Hz (on/off switch time = 3 μs:[2] μs) npj Clean Water (2019) 16
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