[Property analysis of nanosized iron sulfide produced by sulfate reducing bacteria and its application in the treatment of wastewater containing high concentration of Cr (VI)].

The properties of novel nanosized iron sulphide produced by sulfate reducing bacteria (SRB) and its application to the removal of Cr (VI) from wastewater were studied. The structural properties were examined by transmission electron microscope (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The influences of pH, temperature and dosage on removal of Cr (VI) from wastewater by nanosized iron sulphide were investigated, and the effect comparison of nanosized iron sulphide and other traditional wastewater treatment was also evaluated. TEM result shows that the length of the nanosized iron sulphide is approximately 45-80 nm, and the ratio of length to width is 10-15. XPS and XRD results indicate that the Fe/S is 1.07-1.11, and the main composition of nanosized iron sulphide is amorphous FeS and mackinawite. While in treating wastewater containing Cr (V), pH, temperature and dosage of nanosized iron sulphide are the main factors to control the reaction. The Cr (VI) reduction rate increases with decrease of pH and increase of dosage and temperature. Among these factors, pH is the most significant influence factor. At 25 degrees C, pH 3, when the mole ratio of nanosized iron sulphide to chromium (VI) reaches 1.17/1, wastewater containing Cr (VI) 0.03 mol/L can be treated to meet the discharge standard within 10 min. Moreover, in treating wastewater containing Cr (VI), compared with commercial iron sulfide (AR.), nanosized iron sulphide has advantages of low dosage and short treatment time, and compared to conventional biological treatment by SRB, nanosized iron sulphide has advantages of low effluent COD and small amount of sludge.