Green synthesis and characterization of Curcumin functionalized MIL-88 A metal organic framework for reactive blue dye removal optimized by response surface methodology.

Abstract

The persistent presence of reactive dyes in textile wastewater poses a significant environmental challenge due to their resistance to conventional treatment methods. In this study, a novel Curcumin-functionalized MIL-88 A metal-organic framework (MOF) was synthesized using a green, ethanol-based method for the enhanced removal of reactive blue dye from aqueous solutions. The composite was characterized using FTIR, XRD, FESEM, EDS, BET, and UV-vis spectroscopy. FTIR analysis confirmed successful curcumin functionalization, XRD patterns showed the retention of MIL-88 A crystallinity, and FESEM revealed well-defined spindle-shaped particles with curcumin coating. EDS indicated increased carbon content, while BET analysis demonstrated enhancements in surface area (from 32.35 to 39.70 m²/g) and pore volume (from 0.2816 to 0.3582 cm³/g), improving the material's adsorption performance. Under optimized UV-assisted conditions (pH 4, 0.080 g adsorbent, 50.953 min), the Curcumin/MIL-88 A composite achieved a removal efficiency of 99.98% in the first cycle and a maximum adsorption capacity of 80.89 mg/g based on Langmuir isotherm fitting. Kinetic studies showed that the pseudo-second-order model best described the adsorption behavior, suggesting chemisorption as the dominant mechanism. Isotherm modeling indicated that the Freundlich model provided the best fit, implying multilayer adsorption on a heterogeneous surface. These results confirm a synergistic removal mechanism involving both adsorption and photodegradation. The Curcumin/MIL-88 A composite thus represents a promising, reusable candidate for sustainable wastewater treatment.