Fabricating iron-cobalt layered double hydroxide derived from metal-organic framework for the activation of peroxymonosulfate towards tetracycline degradation

Herein, iron-cobalt layered double hydroxide (FeCo-LDH) was synthesized by sacrificing Co-containing zeolite imidazolate framework materials (ZIF-67) in iron ethanolic solution at room temperature. The catalytic performances of catalysts were investigated by activating peroxymonosulfate (PMS) for tetracycline (TC) degradation. Experimental results were demonstrated that FeCo-LDH with molar ratios of Fe and Co was 1.5 (FeCo-LDH-1.5) exhibited the highest catalytic activity, in which the TC degradation efficiency was reached to 92% within 5 min. The system of FeCo-LDH-1.5/PMS exhibited high stability and high efficiency in the influencing factor experiments including TC concentrations, initial pH, coexisting anions (Na+, Cl-, SO42-) and humic acid (HA). Results of quenching experiments and electron paramagnetic resonance (EPR) characterization showed that O-2(center dot-) and SO4 center dot- radicals were the foremost reactive species for TC degradation. Liquid chromatograph - mass spectrometer (LCMS) and three-dimensional excitation emission matrix fluorescence spectro photometer (3D EEMs) were conducted to investigate the degradation intermediate and possible degradation pathway. Moreover, high degradation efficiency was implemented in actual wastewater by the FeCo-LDH-1.5/PMS system. Compared to Fe3+/ PMS and Co2+/PMS homogeneous system, the FeCo-LDH-1.5/PMS system was exhibited advantages in catalytic activity and high reusability. This study provided a convenient method to synthesis advanced hydrotalcite-like catalysts, which showed remarkable performance in actual wastewater treatment.