Fabrication of NiO/Mg–Al layered double hydroxide with superior performance for peroxydisulfate activation

Abstract

Mg–Al Layered double hydroxides (LDH) with weak alkalinity can improve the activity and stability of transitional metal oxides for peroxydisulfate (PDS) activation. Herein, NiO supported on LDH (Ni-LDH-TP) and Ni doped LDH samples (Ni-LDH-CP and Ni-LDH-SP) were prepared by two-step precipitation and co-precipitation methods, respectively. Their structure and surface properties were characterized and their performance for PDS activation was compared using ciprofloxacin as the target pollutant. The results indicate that Ni-LDH-TP exhibited much higher activity than Ni-LDH-CP and Ni-LDH-SP due to its more surface exposed NiO. The two-step precipitation method should be a better alternative for the synthesis of Ni-LDH catalyst for PDS activation. Ni-LDH-TP exhibited high activity over a wide pH range and good reusability in the presence of bicarbonate, demonstrating its potential application in real water treatment. Activated PDS and SO4•− should be the dominant reactive species for ciprofloxacin degradation. This finding provides an effective strategy for preparing Ni-based PDS catalyst.