Adsorption and biodegradation of dye in wastewater with Fe3O4@MIL-100 (Fe) core–shell bio-nanocomposites

Adsorption and improved biodegradation of dyes in wastewater was achieved with Fe3O4@MIL-100 core-shell bio-nanocomposites, which were prepared by a step-by-step strategy and attached to the surface of bacteria via zero-length carbodiimide chemistry. The Fe3O4@MIL-100 (Fe) nano-composite showed excellent dye adsorption properties and the overall dye removal process followed second-order kinetics. The dye AO10 was completely eliminated from solution by the combined effects of adsorption and biodegradation within 15 and 25 h from initial dye concentrations of 25 and 50 mg/L, respectively. The time to degrade the dye decreased from 11 h for the free microorganisms to 5 h for the bio-nanocomposite. The procedure was non-toxic, allowed for magnetic separation of the bio-nanocomposite from solution, and showed good cycling performance for the removal of dye. Hence, the strategy of surface-engineering bacteria shows great potential for the treatment of dyes from industrial effluents.