Novel biocomposite of Pseudomonas aeruginosa supported by metal-organic framework UiO-66 in sodium alginate-polyvinyl alcohol matrices for methylene blue decolorization: Effect of crosslinking agents and optimization using response surface methodology.

The excessive use of synthetic dyes in textile industry is significantly causing water pollution due to their toxicity and resistance to degradation. Therefore, this study aimed to investigate the immobilization of the dye-degrading bacterium Pseudomonas aeruginosa supported by the metal-organic framework (MOF) UiO-66 in sodium alginate-polyvinyl alcohol (SA-PVA) matrices to enhance methylene blue (MB) decolorization. Different crosslinkers, such as CaCl, CaCl/boric acid (CaCl/BA), CaCl/glutaraldehyde (CaCl/GA), and CaCl/boric acid/glutaraldehyde (CaCl/BA/GA) were used to fabricate the SA/PVA@UiO-66/P. aeruginosa beads. XRD, FTIR, SEM-EDS, and zeta potential analyzer were also used to examine chemical structure, composition, and morphology of beads. This was followed by beads screening through MB decolorization assay and reusability tests that were carried out to determine the most optimal variant. The results showed that beads crosslinked by CaCl/BA had the highest decolorization efficiency (92.28%) within 24 h and remained reusable for 7 cycles with efficiency >40% compared to beads crosslinked by CaCl (85.91%), CaCl/BA/GA (84.02%), and CaCl/GA (70.46%). Further optimization using Response Surface Methodology (RSM) showed the ideal MB decolorization conditions by SA/PVA@UiO-66/P. aeruginosa beads at pH 7.40, 36.16°C, 54.82 h. Decolorization efficiency of 96.54% was obtained by experimental verification under these conditions, which was consistent with RSM prediction of 96.45%. These results suggested a substantial potential application of the composite material for MB removal in textile wastewater treatment.

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