| The study utilizes the conventional dual-chamber microbial fuel cell (MFC), and modifies the cathode by natural pyrrhotite, then applies it to the treatment of Cr (VI)-containing wastewater. Make pyrrhotite powder taken from a large pyrite ore in Inner Mongolia after a series of processes to obtain a particle size of less than 44um, and polyvinylidene fluoride (binder) mix in a certain mass ratio to form a homogeneous paste, then smear it on the graphite to obtain the pyrrhotite-coated-electrode.Take the modified electrode as the fuel cell’s cathode, the cathode of graphite without modification as contrast group, K3[Fe(CN)6] as electron acceptor, and determine the power density and polarization curves of the cell. The curve of the power density shows the pyrrhotite-coated-cathode produces the maximum power density 150.0W/m3, increasing to 157%compared to the graphite cathode. The polarization curves shows the polarization resistance of the system is only 48.89Ω when use pyrrhotite to modify the electrode, lower than 141.33Ω corresponding to the cathode of graphite sheet obviously. The results demonstrate that the catalytic effect of natural pyrrhotite is obvious. And using natural pyrrhotite can reduce the loss of cathodic polarization as well as the internal resistance. In the aspect of the performance of producing electricity, it is superior to the cathode of graphite sheet. So the natural pyrrhotite can be used as an efficient catalyst of cathode.Apply pyrrhotite to the treatment of Cr(Ⅵ)-containing wastewater after researching its catalytic properties.The results shows that pyrrhotite-coated-cathode produces higher output voltage than the cathode of graphite sheet;the removal efficiency of Cr (Ⅵ) also increases by 23.4%. Afterwards, do research with large reactor (8cm* 8cm* 8cm) to when the initial concentration of Cr(Ⅵ) is 50mg/L, 1OOmg/L (pH= 2.10). When the initial concentration of Cr(Ⅵ) is 50mg/L, the removal efficiency reaches to 99.0% after 128h’s reaction; at this time, the concentration is 0.5mg/L which meets the maximum allowable concentration for emission of Integrated Wastewater Discharge Standard (GB8979-1996)。In order to study how the initial concentration of Cr(Ⅵ) and pH affect the removal efficiency of Cr(Ⅵ) systematically, the experiment adopts small reactor (D=3cm,H=2cm); then it sets up a series of different initial concentrations of Cr (Ⅵ) (10-150mg/L) with different gradients of pH (3.09-7.00) to learn about their effects on the removal efficiency of Cr(Ⅵ). In the condition of low initial concentration of Cr(Ⅵ) (10,30,50mg/L), the removal efficiency of Cr(Ⅵ) reaches to 99.5% after 45h’s reaction. When the initial concentration of Cr(Ⅵ) is increased to 100mg/L, the removal efficiency reduces from 99.54% to 50.24% as the pH increases from 3 to 7. The results shows that in the condition of high initial concentration of Cr (VI), pH has a significant impact on the removal efficiency of Cr (VI); in order to obtain the desired results, we must reduce the pH. The study achieves the double effect of utilizing waste to control pollution by the means of mine tailing resource’s reuse. Thus, it provides a new idea to the treatment of Cr(VI)-containing wastewater. |
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