Highly selective adsorption of organic dyes containing sulphonic groups using Cu2(OH)3NO3 nanosheets

Abstract

In this study, we report a facile approach to synthesize Cu2(OH)3NO3 nanosheets via simply sonochemical method, which showed high efficiency and selectivity towards the adsorption of organic dyes containing sulphonic groups. The structure and morphology of the nanosheets were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, N2 adsorption–desorption isotherms, particle size and zeta potential analysis. The adsorption results indicated that the equilibrium data coincide very well with Langmuir isotherm, and the maximum adsorption capacities for Congo red, methyl blue and methyl orange were 1864, 1270 and 959 mg g−1, respectively. The kinetic data can be explained by pseudo-second-order model. The Cu2(OH)3NO3 nanosheets also demonstrated high selectivity towards the adsorption of dyes containing sulphonic groups from mixed dye solutions. The rational mechanism of adsorption was attributed to hydrogen bonding, electrostatic attractions and ion exchanges between the dye molecules and Cu2(OH)3NO3 in the adsorption process.