The Removal Of Heavy Metal Ions And Escherichia Coli From Wastewater By Ferrite

Heavy metal ions and bacteria are common pollutants in water bodies, and harmful tohuman body. It is necessary to remove them in a timely manner. The MnFe₂O₄andAg_0.003Mn_0.827Fe2O_3.8285were both synthesized by sol–gel method. respectively for adsorbentto remove heavy metals in water ions and fungicide to kill the E. coli in water.Then the surface properties of the them were explored by SEM, EDS, XRD, FTIR andXPS. The results showed that the two samples both had widely distributed porous structure.The exist of Ag was found in EDS, XRD and XPS of Ag_0.003Mn_0.827Fe2O_3.8285.The adsorptionof Cr（Ⅵ）﹑Ni（Ⅱ）、Pb（Ⅱ） and Cu（Ⅱ） from aqueous solution on magnetic porous spinelMnFe₂O₄was investigated. Single batch technique was employed to test pH effect, sorptionkinetics and isotherm. The results showed that the optimum pH value of Cr（Ⅵ） and Ni（Ⅱ） was2.0and7.0, the equilibrium time was4.0h and2.0h, respectively. The Pb（Ⅱ） and Cu（Ⅱ）removal was also strongly pH–dependent with an optimum pH value of6.0, and theequilibrium time was3.0h. The adsorption process could be described by apseudo–second–order model. The equilibrium data were corresponded well with Langmuirisotherm. The maximum adsorption capacities for Cr（Ⅵ）, Ni（Ⅱ）, Pb（Ⅱ） and Cu（Ⅱ） were38.00mg/g,171.71mg/g,73.47mg/g and63.94mg/g, respectively. The interaction mechanismand the regeneration were also explored. The adsorbed Pb（Ⅱ） and Cu（Ⅱ） were in the form ofthe complex with oxygen in carboxyl groups and hydroxyl groups banding on MnFe₂O₄surface. The sorbent could be reused for five times with high removal efficiency.The inactivation of Escherichia coli （E.coli） from aqueous solution onAg_0.003Mn_0.827Fe2O_3.8285was investigated. Batch experiments were conducted to investigatethe effect of silver content, does of Ag_0.003Mn_0.827Fe2O_3.8285, light, reaction time, concentrationof E.coli, temperature, pH value, ons dissolve and hydroxy inhibitor. TheAg_0.003Mn_0.827Fe2O_3.8285was found to be highly effective at killing E. coli without light andcould completely inactivate2×10⁷cfu/mL E. coli within2h. The optimal removal effect wasobtained when pH was7.0. Meanwhile, more inactivation of E. coli was observed at alkalinepH than at acid pH in Ag_0.003Mn_0.827Fe2O_3.8285suspension. Higher temperature was beneficialto increased the bactericidal efficiency. Moreover, the mechanism of bactericidal action for the Ag_0.003Mn_0.827Fe2O_3.8285wasinvestigated by scanning SEM and AFM. The results showed that lots of E. coli adhered to thesurfaces of Ag_0.003Mn_0.827Fe2O_3.8285closely and the cell membrane of the bacterium has beendisrupted after reaction. The enzymatic activity of E. coli was also reduced after mixed withAg_0.003Mn_0.827Fe2O_3.8285for a period interaction as measured. The Ag_0.003Mn_0.827Fe2O_3.8285could be reused for five times with high removal efficiency. This work provides a potentialeffective material to be used in the antimicrobial applications.