Synthesis of sodium alginate/carboxy-methyl cellulose/Cu-based metal-organic framework composite for adsorption of tetracycline from aqueous solution: Isotherm, kinetic and thermodynamic approach

Sodium alginate/carboxy-methyl cellulose/Cu-based metal-organic framework (SA/CMC/Cu-BDC) nanocomposite beads were prepared using an ex-situ combination of natural bio-polymers and pre-synthesized Cu-BDC powder and freeze-drying. Several methods such as XRD, FTIR, EDX, SEM, and N₂ adsorption-desorption were used to pinpoint the physical and chemical properties of as-prepared materials. Cu-BDC particles distributed in the interior porosity of two-biopolymeric composites as revealed by SEM. The composite beads prepared by 30 wt% Cu-BDC particles showed approximately high surface area with micro and meso cavities. Batch adsorption experiments were carried out to explore the adsorption performance of Tetracycline (TC) antibiotic. Results showed that maximum adsorption efficiency of TC was attained at pH 7 using SA/CMC/Cu-BDC composite beads with 30 wt% loading of Cu-BDC powder. The effects of two biopolymeric composite compared with one biopolymeric composites was explored; results showed that SA/CMC/Cu-BDC 30 wt% have higher maximum adsorption capacity (180.5 mg g⁻¹) compared to the SA/Cu-BDC 30 wt% (127 mg g⁻¹). The isotherm equilibrium and kinetic data for TC adsorption onto SA/CMC/Cu-BDC followed Langmuir isotherm model and pseudo-second-order kinetic model, respectively. Thermodynamical parameters revealed that TC adsorption is spontaneous with endothermic nature.