One-step preparation, characterization and adsorption property of mesoporous nickel sulfides in deep eutectic solvent

In this paper, single and mixed-phase mesoporous nickel sulfides (including alpha-NiS/beta-NiS/Ni3S4, Ni3S4, Ni3S4/NiS2 and NiS2) are prepared in choline chloride-ethylene glycol deep eutectic solvent (ChCl-EG DES) under normal atmosphere. In the preparation processes, the ChCl-EG DES plays dual roles as solvent and template. The effects of NiSO4 center dot 6H(2)O, Na2S2O3 center dot 5H(2)O and ethylenediamine tetraacetic acid concentrations on the phase, morphology, element composition and specific surface area of the products are examined. The results show that pompon-like, cauliflower-like, botryoid and nanospherical nickel sulfides can be obtained by controlling the concentration of the reactants. Their specific surface areas are 4.063 m(2)/g, 5.138 m(2)/g, 4.533 m(2)/g and 52.135 m(2)/g, respectively. The reaction mechanism for the preparation of nickel sulfides in ChCl-EG DES is also elaborated. In addition, the adsorption property and mechanism of nickel sulfides are assessed with methylene blue (MB) as target organic pollutant. The adsorption process on MB follows the pseudo-second-order kinetics and Langmuir isotherm models. Their maximum adsorption capacity for MB are 20.39 mg g(-1), 19.56 mg g(-1), 21.38 mg g(-1) and 24.38 mg g(-1), respectively.

Automated summary

In this study, single and mixed-phase mesoporous nickel sulfides were successfully prepared using ChCl-EG DES as a solvent and template. The effects of reactant concentrations on the phase, morphology, element composition, and specific surface area of the products were investigated. The adsorption property and mechanism of nickel sulfides towards methylene blue were also evaluated.