Fast removal of Congo red from aqueous solution by adsorption onto micro/nanostructured NiO microspheres

摘要

Micro/nanostructured nickel carbonate hydroxide microspheres were synthesized by a ethylene glycol ((CH_2OH)_2, EG) mediated solvothermal method. The chemical composition of it was determined by X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and thermal gravimetric analysis. After calcination, mesoporous micro/nanostructured NiO microspheres with a large surface area of 185.1 m~2 g~(-1) were prepared. The adsorption properties towards Congo red (CR) were revealed. The adsorption of CR was well fitted by the Langmuir model, and the maximum adsorption capacity was 456.8 mg g~(-1). Kinetic experiment results can be described by the pseudo-second-order model. Furthermore, with the initial concen- tration of 300 mg L~(-1) of CR, over 99.41% of CR was removed within 1 min. The calculated thermodynamic parameters including the enthalpy change, change in the free Gibbs energy, entropy change revealed that the adsorption of CR on NiO microspheres was a feasible, spontaneous and endothermic process.