Development of stable agar/carrageenan-Fe3O4-Klebsiella pneumoniae composite beads for efficient phenol degradation

Abstract

It's of practical importance but highly challenging for cell immobilization supports to maintain mechanical strength and reduce microbial leakage in environmental and industrial applications. Herein, we developed an agar/κ-carrageenan composite hydrogel to entrap Klebsiella pneumoniae with the combination of nano-Fe3O4 for processing phenol wastes. The agar/carrageenan-K. pneumoniae composite bead showed good pelletizing properties, superior material strength and high cell loading. Introduction of nano-Fe3O4 to the composite gel further enhanced phenol degradation rate by >10% owing to strengthened phenol oxidation by Fe3O4-induced hydroxyl radicals (·OH) and improved mass and electron transfers. 50 successive cycles of degradation and recycling using the agar/carrageenan-K. pneumoniae composite bead showed that 1500 mg/L phenol was fully degraded for all cycles with the highest rate of 55.12 mg L−1·h−1 obtained at the 15th cycles. The improved stability and recyclability render the as-prepared immobilized phenol-degrading bacteria with great potential for industrial applications.