Adsorptive removal of crystal violet from aqueous solution by ultrasonic-assisted synthesized zirconium-2,6-naphthalenedicarboxylate metal-organic framework.

Zirconium-2,6-naphthalenedicarboxylate metal-organic framework (Zr-NDC MOF) was prepared using ultrasound-assisted synthesis and tested for the adsorptive removal of crystal violet (CV) dye from aqueous solution. The pristine Zr-NDC was characterized using powder X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, and energy-dispersive X-ray spectroscopy, Fourier-transform infrared, elemental analysis, and dynamic light scattering techniques. The maximum percentage removal of CV dye was found to be 99.45% with an initial dye concentration of 10 mg L. The kinetics and adsorption isotherm models were used to investigate the removal of CV dye from aqueous solution using Zr-NDC. Langmuir adsorption isotherm model (R = 0.9880) describes the adsorption of CV dye onto Zr-NDC and the maximum equilibrium adsorption capacity (454.2 mg g) was achieved with the CV dye having an initial concentration of 100 mg L. The adsorption was found to follow pseudo-second-order kinetics (R = 0.9960) with a rate constant of 6.52 × 10 g mg min. The effect of various parameters such as dye concentration, contact time, pH of dye solution, and MOF dose on the adsorption of dye was investigated. The study proved that the Zr-NDC is a promising adsorbent in the removal of CV dye from aqueous solution.