Efficient degradation of Rhodamine B by magnetically recoverable Fe_(3)O_(4)-modified ternary CoFeCu-layered double hydroxides via activating peroxymonosulfate

Environment-friendly nano-catalysts capable of activating peroxymonosulfate(PMS)have received increasing attention recently.Nevertheless,traditional nano-catalysts are generally well dispersed and difficult to be separated from reaction system,so it is particularly important to develop nano-catalysts with both good catalytic activity and excellent recycling efficiency.In this work,magnetically recoverable Fe_(3)O_(4)-modified ternary CoFeCu-layered double hydroxides(Fe_(3)O_(4)/CoFeCu-LDHs)was prepared by a simple co-precipitation method and initially applied to activate PMS for the degradation of Rhodamine B(Rh B).X-ray diffraction(XRD),fourier transform infrared spectrometer(FT-IR),scanning electron microscope(SEM),transmission electron microscopy(TEM),Brunauer-Emmett-Teller method(BET),and vibrating sample magnetometer(VSM)were applied to characterize morphology,structure,specific surface area and magnetism.In addition,the effects of several key parameters were evaluated.The Fe_(3)O_(4)/CoFeCu-LDHs exhibited high catalytic activity,and Rh B degradation efficiency could reach 100%within 20 min by adding 0.2 g/L of catalyst and 1 mmol/L of PMS into 50 mg/L of Rh B solution under a wide pH condition(3.0-7.0).Notably,the Fe_(3)O_(4)/CoFeCu-LDHs showed good super-paramagnetism and excellent stability,which could be effectively and quickly recovered under magnetic condition,and the degradation efficiency after ten cycles could still maintain 98.95%.Both radicals quenching tests and electron spin resonance(ESR)identified both HO·and SO_(4)^(·-) were involved and SO_(4)^(·-) played a dominant role on the RhB degradation.Finally,the chemical states of the sample’s surface elements were measured by X-ray photoelectron spectroscopy(XPS),and the possible activation mechanism in Fe_(3)O_(4)/CoFeCu-LDHs/PMS system was proposed according to comprehensive analysis.