Enhanced Methyl Orange Removal Using a Newly Isolated Bacterial Strain and Potassium-Iodide-Doped Hydroxyapatite Nanoparticles

摘要

Due to the toxicity and mutagenicity of methyl orange (MO), it is necessary to eliminate MO from wastewater. A bacterial strain is isolated and identified that possesses a high MO decolorization ability. Furthermore, the cultural requirements and the decolorization behavior of the bacterial isolate are investigated. Potassiumiodidedoped hydroxyapatite (KIdoped HAp) nanoparticles are synthesized and characterized. The enhancement of the decolorization rate using KIdoped HAp nanoparticles is experimentally confirmed. The microbial toxicity assessment is evaluated against Bacillus subtilis, and the bacterial isolate is identified as the Enterococcus faecalis strain Kilany MO under accession number KY780590. This strain shows maximum decolorization of MO (86.4%) at 400mgL1, pH 6, and 30°C for 48h under static conditions. In addition, being extremely tolerant of concentrations of MO of up to 1000mgL1 or more, E. faecalis exhibited decolorizing activity through biosorption rather than adsorption. Scanning electron microscopy and energy dispersive Xray spectra revealed that KIdoped HAp nanoparticles are nanorods that are 50100nm in size with a Ca/P molar ratio of 1.833. KIdoped HAp nanoparticles enhanced decolorization, yielding a maximum removal of 95% within 48h. A microbial toxicity study revealed that the bacterial metabolites are less toxic than MO. Hence, the potential of E. faecalis to withstand high concentrations of MO, especially in the presence of nanoparticles, may start a new trend in wastewater bioremediation strategy.