Convenient synthesis of metal organic framework nanocomposites MOF:Fe(II)-CMC for effective adsorption to treat water samples from cationic pollutants dyes

Abstract

The simple synthesis of an iron-based metal–organic framework nanocomposites (MOF:Fe(II)-CMC) has been successfully performed. The distinctive characteristics of the MOF nanocomposites were analyzed using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) for morphology visualization, Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), energy-dispersive X-ray spectroscopy (EDX), Brunauer–Emmett–Teller (BET) surface area analysis, and zeta potential measurements. The adsorptive potential was established utilizing the cationic dyes (methylene blue, MB), crystal violet (CV), and malachite green (MG) water pollutants. The synthesized MOF:Fe(II)-CMC nanocomposites owned a crystalline microporous–mesoporous structure with a large surface area. The equilibrium data best conformed to the Langmuir isotherm model with correlation coefficient (R² > 0.994) and pseudo-second-order kinetic model, with the maximum adsorption capacity for MB, CV, and MG being 166.66 mg/g at pH 5, 188.67 mg/g at pH 7, and 175.43 mg/g at pH 4, correspondingly at room temperature with an equilibrium concentration of 0.1 mg/ml. Thermodynamic analysis displayed the good energetics (∆G and ∆S < 0) and exothermic nature (∆H < 0) of the adsorption process. Negligible degradation of the adsorptive performance was noted under high ionic strength solutions and simulated water samples. MOF:Fe(II)-CMC exhibited great regenerative potential by ethanol stripping for at least 5 regeneration cycles with an adsorption capacity not less than 90%. The current findings give significant insights into the eco-friendly synthesis process of MOF:Fe(II)-CMC, with great upscaling prospects for the successful treatment of water pollutants, especially in high-strength water samples with complex water matrices.