Research On The Mechanism And Technology Of Sonoelectrochemistry Treatment Refractory Organics

It is expensive and inefficient with the general method in refractory organics because of their particularity. A new method that sonoelectrochemical on the degradation of refractory organics by Pd modified Ti electrode was selected. Meanwhile, the degradation ability and effect factors of organics on the sonochemical, electrochemical or sonoelectrochemical were compared, and the degradation process and mechanism of refractory organic on the sonoelectrochemical was researched. Our experiments have proved that it is an effective method in the degradation of organics.The first part of dissertation, we prepared the Pd modified Ti electrodes (Pd/Ti electrode) and studied it catalytic performance by cyclic voltammetry. The results showed that the Pd/Ti electrodes had better catalytic ability for chlorobenzene and nitrobenzene than pure Ti electrodes. Their cyclic voltammetries of Pd/Ti electrode all showed new reduction peak or oxidation peak, and the reduction and oxidation currents of reaction were significantly higher than pure Ti electrode.The second part of dissertation, the effects of ultrasonic intensity, cell voltage, pH value, reaction time and the dosage of electrolyte etc on the sonoelectrochemical were studied. The cell voltage, reaction time and the dosage of electrolyte are the main effect parameters of sonoelectrochemical. The apparent reaction rate of chlorobezene and nitrobenzene increased with cell voltage, reaction time and the dosage of electrolyte, but it began to keep invariant after an especially numerical value. The degradation ability of sonoelectrochemical for chlorobenzene or nitrobenzene was better in acidic or alkaline than others pH value. The result of experiments showed that the best remove condition was cell voltage 15 V, pH value 12, reaction time 60 minute and electrolyte concentration 0.1 mol/L.The CODCr removal rates of chlorobenzene and nitrobenzene wastewater on the sonochemical, electrochemical and sonoelectrochemical were compared. Although ultrasound could not produce signigicant chemical degradation for chlorobenzene and nitrobenzene, it greatly improved the electrochemical reaction rate. Comparing to electrochemical, the CODCr removal rates of chlorobenzene and nitrobenzene waste water are 1.2 times and 2.2 times when cell voltage is 15 V, and 1.7 times and 2 times when pH value is 12 on the sonoelectrochemical. Meanwhile, the CODCr removal rate got to 75.02% or 78.7% when reaction time is 60 minutes for sonoelectrochemical degradation process, but it could't reach to this rate until to 180 minutes on the electrochemical degradation process.The third part of dissertation, take congored as an example, we discussed the elementary degradation mechanism of refractory organics by sonoelectrochemical method. From experimental results, the degradation ability of sonoelectrochemical for Congo Red was very well. The decoloration rate reached 99.03% and the CODCr removal rate reached 97.51%. Through ultraviolet spectrum analysis, the Congo Red had been degraded to CO2 and water by sonoelectrochemical. Meanwhile, through analysis and research the experimental results, they showed that the elementary degradation mechanism of organics by sonoelectrochemical treatment is the synergistic effect of sonochemical and electrochemical, and they are mutual influence and improve.In this dissertation, we studied an novel water treatment method: sonoelectro- chemical wastewater treatment. The results showd that sonoelectrochemical can degrade and remove organic very well, especially refractory organics and persistent organic pollutants. In the field of wastewater advanced treatment, the sonoelectro- chemical has an well application prospect.