Biodecolorization and Biodegradation of Methyl Orange by Immobilized Pseudomonas aeruginosa Bacterium into SA/PVA Matrix Integrated with MOF UiO-66 Adsorbent

Azo dye, such as methyl orange (MO), is characterized by environmental concerns due to persistence, toxicity, and potential carcinogenic effects. Therefore, this study aimed to investigate the integration of immobilized Pseudomonas aeruginosa (PA) and UiO-66, a zirconium-based metal-organic framework (MOF), into sodium alginate/polyvinyl alcohol (SA/PVA) matrix for biodecolorization and biodegradation of MO dye. Material characterization was carried out by using X-ray diffraction (XRD), Fourier-transform infrared (FTIR), and scanning electron microscopy-energy dispersive X-ray (SEM-EDX) which showed the successful formation of UiO-66 and stable incorporation in SA/PVA/PA beads. The results of adsorption experiments showed that the presence of UiO-66 enhanced MO adsorption capacity by 20.47 % compared to SA/PVA/PA matrix without UiO-66. Kinetic analysis followed the pseudo-second-order model, and adsorption isotherm was best described by the Langmuir model, showing monolayer adsorption behavior. Furthermore, biodecolorization results showed that SA/PVA/UiO-66/PA beads achieved a 92.03 % MO removal rate, indicating a 33.99 % higher than free PA cells. Liquid chromatography–mass spectrometry (LC-MS) analysis confirmed the formation of nine biodegradation products, suggesting successful structural breakdown of MO. These results showed that combining UiO-66 with immobilized PA significantly enhanced both adsorption and biodegradation performance toward MO treatment.