Study On The Electrocatalytic Degradation Of Organic Contaminants Using Carbon Fiber Coupled With Metalphthalocyanine Electrode

With the rapid development of industrialization and urbanization, water pollution is becoming more and more prominent. Wastewater originates from non-biodegradable and toxic industrial or agricultural organic contaminants, such as dyes, phenols, antibiotics and pesticides, which cause serious and long-term harm to environment and human beings. These pollutants have the characteristics of complicated composition, high colority, and high chemical oxygen demand, the traditional physical and biological methods are especially difficult to degrade them. Advanced oxidation processes （AOPs） can produce strong oxidation reactive species, which could quickly degrade organic pollutants into biochemical and small molecules or completely mineralized, but they need to add additional reagents. In recent years, electrochemical advanced oxidation processes （EAOPs） are gradually developed, in situ production of H₂O₂ by reducing O₂ at the cathode. The processes are commonly performed at room temperature and atmospheric pressure, which can be easily controlled. Since electrons are the direct participants of reaction, EAOPs are green and clean technologies.A variety of electrodes of different materials have been reported, however, some inevitable drawbacks still exist. For example, low oxygen evolution potential, short service lifetime. Therefore, there is an urgent need to develop new electrocatalytic systems based on efficient and stable electrodes. Metal phthalocyanine complexes （MPcs） have received increasing scientific interest, since their activities are similar to enzymes, excellent chemical stability and electrical conductivity, and they are used extensively as catalysts for the degradation of organic contaminants. But small molecules are difficult to recycle, which can cause secondary pollution. This problem can be solved by supporting MPcs on carriers. Carbon fiber （CF） has unusual chemical stability and conductivity, and could be used for the immobilization of enzymes and catalysts. The introduction of CF could facilitate contaminants mass transfer from bulk solution to the electrode surface. Therefore, we consider using CF as the carrier of MPcs to prepare electrode.CoTAPc and FePc（NO₂）₃NH₂ are anchored covalently on CF using an easy and moderate one-step deamination method to prepare catalytic electrodes. The catalytic electrodes have improved stability and higher electrocatalytic activity to organic contaminants. The effects of potential, pH, electrolyte concentrations on electrocatalytic efficiencies were investigated, respectively. It indicated that the removal rate of organic contaminants could be slightly increase with the increase of potential. When the potential was too high, iron phthalocyanine could be oxidized and the degradation efficiency would be affected. Therefore,2.5 V was selected as the optimum potential. The two electrodes exhibited relatively high electrochemical activity over a wide pH range. The removal rate of pollutants increased gradually with an increase in electrolyte concentration, but there had no significant effects on removal efficiency in a certain concentration range. Therefore, the optimum value of the electrolyte concentration is 0.1 mol/L. Repetitive tests showed that two electrodes could maintain high electrocatalytic activity over several cycles. The two electrocatalytic systems could be used to eliminate many kinds of contaminants with different structures. The electrocatalytic activities of two electrodes were nearly independent of high isopropanol concentration. EPR tests showed that the two systems provided a non-hydroxyl radical reaction mechanism. We speculate that the electrocatalytic elimination of pollutants in two systems may be attributed to the high-valent metal-oxo intermediate. The intermediate and final products of carbamazepine oxidazed by FePc（NO2）3-CF electrode were tested by UPLC-HDMS technology. The possible electrocatalytic degradation pathway of CBZ was proposed.