Enhancement Of MTBE Biodegradation By Fe₃O₄ Magnetic Particles

Magnetic particles?MPs?have been rapidly applied to bioremediation of environmental pollutions.With the promising performance,magnetic particles are getting attention to enhancing biodegradation activity to treat the volatile organic compounds?VOCs?from contaminated sites.The reusability,reactivity,and biocompatibility properties of the magnetic particles reduce the current environmental issues.Magnetic particles?MPs?can enhance the biodegradation of the methyl tert-butyl ether?MTBE?in the batch scale.The effect of Fe₃O₄ MPs with the different sizes and amounts on the performance of degradation rate and microbial growth was checked.Moreover,the morphological structure of the magnetic particles was characterized by scanning electron microscope?SEM?,telescopic electron microscope?TEM?,X-ray diffraction?XRD?and vibrating sample magnetometer?VSM?.The average size of the synthesized magnetic nanoparticles was found to be in the range from 10nm to 25 nm.The results of TEM and SEM demonstrated that the uncoated magnetic particles have better MTBE-adsorption capacity.The cross-sectional analysis of the transmission electron microscope?TEM?found that the Fe₃O₄nanoparticles were adsorbed on the surfaces of the cells;in the case of the Fe₃O₄microparticles,the cells were adsorbed on the surface of the magnetic particles.The Fe₃O₄ MPs could enhance biodegradation activity and cell reusability.The maximum specific growth rate with different substrate concentrations was calculated by the Monod method.The specific growth rate(?_max)of the cells with and without Fe₃O₄ addition was 0.06641 h^-1 and 0.04883 h^-1,respectively.The magnetic microparticles and synthesized nanoparticles had similar degradation enhancement effect.MTBE with the maximum initial concentration of 850 mg/L was completely degraded by the Methylibium petroleiphilum PM1 within 80 hours in the presence of Fe₃O₄ MPs,while within 140 hours in the absence of MPs.The Fe₃O₄ micro particles performed good reusability and obtained 100%of MTBE removal efficiency even up to 8 cycles within 250 hours.The biodegradation rate was higher in the cells immobilized with MPs,probably due to the relatively higher microbial activity toward MTBE.The experiment results show that the usage of MPs is a good alternative for the enhancement of MTBE degradation.