| The anthraquinone redox intermediates?anthraquinone-2-sulfonate,AQS?and the electrode interaction process were used as the object of study.During the process,the electron transfer characteristics and influencing factors on the surface of the carbon felt electrode were investigated,and the interaction between iron minerals and electrode was investigated with AQS as electron shuttle.On the basis of optimizing the experimental conditions,the commercially available carbon felt electrode was used as the working electrode,which overcame the shortcomings of the carbon felt electrode.Compared with ordinary glassy carbon electrode,the AQS in the reaction of carbon felt electrode surface sensitivity and reproducibility had been significantly improved.Compared the electron transfer ability of the non-modified carbon felt,modified carbon felt,non-modified carbon rod and modified carbon rod selected the best conditions to establish“electrode-anthraquinone-iron minerals”system.The results showed that the sensitivity of AQS reacts with the electrode had been improved,and the current peak(Imax)and transfer power?Q?were linearly related to AQS content?C?;the higher the AQS concentration,the higher the rate difference of electron transfer with ultrasonic opening conditions,the lower concentration difference current was 1.82 mC/s and the high was 5.44 mC/s;Cyclic Voltammetry?CV?scanning curves showed that AQS had obvious reaction process at the electrode surface under ultrasonic assisted conditions,but without ultrasonic conditions the process was weak;The Electrochemical Impedance Spectroscopy?EIS?showed that activation resistance of carbon felt electrodes were significantly reduced under ultrasonic condition,that promoted electronic transfer on the electrode surface.When the applied electrode is subjected to-0.5 V with ultrasonic,the apparent rate constant of electron transfer was 159 s-1,which was 98.55 s-1 without ultrasound.In the ultrasonic assist condition,regarded carbon felt electrode as the working electrode,compared with ordinary glassy carbon electrode,overcame the disadvantages of carbon felt electrode passivation,that could significantly improved electrode sensitivity and reproducibility with AQS.Under the condition of ultrasonic assisted condition,the capacity of the carbon felt electrode and the carbon rod under different modification conditions had been investigated.The experimental results illustrated that the unmodified carbon felt had the best electrochemical performance as electrode,and the second one was pyrrole?PPy?independent modification,and the last was the AQS and PPy synergistic modification;for the carbon rod electrode was the opposite,with the AQS modified carbon rod electrode was better than without AQS modified.However,in general,carbon felt was much better than carbon rod electrodes.Treated the non-modified carbon felt electrode as the working electrode with ultrasonic condition,design experimental system,AQS was used as electron mediator to reduction of solid iron minerals,the establishment of“electrode-anthraquinone-iron minerals”system,the test results showed that:the different iron minerals had different reaction rate,that the average apparent reaction rate constants of ferrihydrite,hematite,lepidocrocite and goethite in 0.01 mmol/L AQS system were 2.07×10-5 s-1,2.0×10-6 s-1,3.0×10-6 s-1,1.0×10-6 s-1,and at 0.05 mmol/L AQS in the system were 3.18×10-5 s-1,7.3×10-6 s-1,7.9×10-6 s-1,4.1×10-6 s-1;the value was clearly reflected in the difficulty of the reaction of various iron minerals:ferrihydrite>lepidocrocite>hematite>goethite,and the greater the concentration of AQS,the faster reaction could be displayed. |
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