Preparation Of Co, Cu Modified Kaolin Catalyst And The Study Of Its Application In Electrochemical Degradation Of Wastewater

The environmental pollution problem caused by industrial development is becoming one of a serious problem in this century. At the background of saving natural resources and sustainable development, it demands the cleaner and more environmental methods to deal with the wastes that the industrial plants produced. Our country is rich for its mineral resources like kaolin, therefore, the use of kaolin and its modification by transition metals Co, Cu was studied and successfully applied in our multi-phase electrochemical degradation process. The system was designed using double anodes and was used to treat various pollutions like anionic surfactants (DBS), aniline simulated wastewater and real paper-making wastewater. Paper emphasized the application of advanced chemical oxidation techniques to solve the environmental pollutions, its high efficiency and low cost may have a certain application aspect in the future environmental field.The first part of this article is to use kaolin as carrier, synthesize the CoO-Cu₂O-PO₄^3- modified catalyst. Study indicated there's a total difference in its micro-sized morphology, structure and BET surface before and after the modification and activation. The results showed that the previous structure of kaolinite had almost disappeared, the stable Al-O ocatahedron structure in neat kaolin had broken, and the losses in crystallinity and the structural deformation. Its existed large amount of micro-sized particles and its BET surface had been enlarged to 38m²/g.The treatment results were compared using three different systems (multi-phase electrochemical system, traditional two-electrode electrochemical system and only catalyst existed system) to eliminate the pollutants with DBS, aniline simulated wastewater and real paper-making wastewater in the second part of this article. The amount of electro-produced H₂O₂ and their energy consumption were also studied in this part. The study indicated that the COD degradation rate with three different pollutants under multi-phase electrochemical system was higher than two others by 10% and 40%.The article also discussed the influence of parameters like cell voltage, initial pH, current density and catalyst dose on COD removal rate and the pH variation of the treated solutions with time. The study results showed that when the initial pH was 3, current density was 30mA cm^-2, the COD removal rate with three different pollutants was 90.2%, 80.6%, and 96.8% respectively. The catalyst dose was then studied towards the real paper-making wastewater, the results showed when the catalyst dose increased to 30g/L, there's no substantial change on COD removal rate, while the catalyst dose increased from 1g cm^-3 to 30g cm^-3 the energy consumption decreased from 20.10 to 10.54 KWh/ (Kg COD Removal). Further discussion about the sustainable use of the treated wastewater was made when using it to irrigate the ornamental clover. The soil TOC, TIC and chlorophyll concentration of clover were selected as parameters to evaluate the using feasibility of the treated water. It had been found that the chlorophyll was hardly been affected, and the variation of TOC and TIC were both in a normal range.Finally, the article discussed the possible mechanism of multi-phase electrochemical degradation of wastewater through the XPS spectrum of the used catalyst's surface: In the acid solutions, the electro-generated O₂ may get electrons on the porous graphite cathode and then form H₂O₂, H₂O₂ may diffused to the surface of catalyst and reacted with its active part to produce OH, which in turn can destruct organics. The catalyst functioned as both the catalyst to decompose H₂O₂ and the flocculants to sedimentate the degraded waste. The influence of C1^- was finally studied when treating the real paper-making wastewater.