Influence of copper and nickel nodes on the adsorption behavior of metal organic framework cellulose nanocrystal and acetate composite films

The influence of metal node identity on the adsorption behavior of cellulose-supported metal-organic framework (MOF) composite films remains poorly understood, as previous studies have generally compared different MOFs prepared using different support materials and fabrication methods. In this work, composite adsorbent films comprising a cellulose acetate (CA) matrix integrated with crystalline nanocellulose (CNC) and either Cu-BDC or Ni-BDC MOFs were fabricated under identical conditions to systematically investigate the influence of metal node selection on their physicochemical properties and adsorption behavior. Comprehensive characterization confirmed successful incorporation of the MOF/CNC phases within the CA matrix and revealed metal node-dependent differences in framework crystallinity, pore architecture and morphology. Despite comparable surface chemistry, surface area and MOF loading, the Cu-BDC/CNC composite exhibited higher framework crystallinity, a more ordered pore architecture and greater adsorption site accessibility than the Ni-BDC/CNC composite. Under the optimum adsorption conditions, the Cu-BDC/CNC film achieved an equilibrium adsorption capacity of 3.60 ± 0.075 mg/g and an MB removal efficiency of 60 ± 1.25%, whereas the Ni-BDC/CNC film achieved 2.78 ± 0.08 mg/g and 46 ± 1.34% removal. Adsorption was best described by the Langmuir isotherm and pseudo-second-order kinetic model. Although the Cu-BDC/CNC exhibited higher adsorption capacity for single-component MB solutions, the Ni-BDC/CNC produced greater reduction in integrated UV-vis spectral absorbance during treatment of real textile effluent, demonstrating the influence of the complex multicomponent matrix on adsorption behavior. This study establishes a clear structure-property performance relationship, demonstrating that MOF metal node selection influences adsorption capacity, adsorption kinetics and adsorption selectivity.