Composition and phase control of Ni/NiO nanoparticles for photocatalytic degradation of EDTA

▶ Sol–gel is a powerful approach to synthesize NiO nanoparticles. ▶ Catalyst phase and composition depend greatly on starting precursors. ▶ The annealing process is crucial for a better catalyst performance. ▶ The catalyst led to complete removal of EDTA under specific conditions. ▶ The reaction of Ni/NiO with EDTA follows first order kinetics. A sol–gel process followed by a calcination treatment was employed to synthesize magnetic Ni/NiO nanoparticles. The as-formed particles were characterized using XRD, TEM, UV–vis, surface area and VSM. The XRD results show that the patterns of the product synthesized using 1:1, 1:2, and 1:3 molar ratio of nickel nitrate/citric acid composed of a mixture of NiO and Ni, whereas the patterns recorded for 2:1 and 3:1 molar ratio exhibited a single NiO phase. All the prepared samples are in the form of nanoparticles with sizes locate in the range of 33 up to 118 nm for the samples prepared by different molar ratios. The photocatalytic tests were conducted for degradation of EDTA. The results show that the EDTA removal efficiency is 99.9% at 3 × 10 −3 M EDTA concentration. The reaction of Ni/NiO with EDTA follows first order kinetics with respect to EDTA. The rate constants and t 1/2 for Ni/NiO at 0.4 g/l catalyst/EDTA solution ratio were, respectively 460 min −1, 15.1 min.