Microwave-assisted Cu-bearing Silicon Carbide Catalyzed Degradation Of Phenol By Persulfate Or Hydrogen Peroxide

Phenol is an important chemical and pharmaceutical raw material and is an intermediate in the synthesis of many higher molecular weight aromatic hydrocarbons.Phenolic wastewater can damage people’s nerves,liver and also damage crops.Phenol and its derivatives are highly soluble in water due to the presence of oxygen atoms in the structure,their migration ability is excellent,so phenol is also one of the main environmental pollutants.Many researchers are currently looking for ways to eliminate environmental pollutants by requiring specific chemical processes to convert this carcinogenic compound into commercially available products.Copper-based silicon carbide（Cu/SiC）can catalyze the formation of·OH or·SO₄^-from H₂O₂ or S₂O₈^2-under microwave irradiation.Organic compounds can be degraded by reacting with·OH or·SO₄^-.The degradation mechanism of phenol under different chemical oxidation conditions by microwave irradiation system was studied.For the development and utilization of phenol wastewater,the prevention and remediation of phenol pollution is of great significance.The main conclusions are as follows:（1）SEM-EDX observation showed that copper oxide was well dispersed on the surface of SiC carrier.XPS analysis showed that copper mainly existed in the valence of+2.Cu/SiC catalyst has an effective catalytic activity in high concentration phenol solution.More than90%of phenol was removed within 6 mins in microwave advanced oxidation process.The catalyst after five cycles showed good activity and stability in activating H₂O₂.（2）The interaction between microwave and catalyst can lead to energy directed to the reaction site of the catalyst,which heating or electro-discharge around the catalyst.The reaction temperature is conducive to the generation and diffusion of active radicals,and the probability of molecular collision is greatly increased.As a semiconductor,Cu/SiC can accelerate and induce electron（e^-）separation under microwave radiation,significantly improving the catalytic capacity of catalysts.The combination of the above factors can promote the degradation of phenol.（3）·OH is generated due to the redox cycle between Cu（I）/Cu（II）,and·OH is the active substance that leads to phenol degradation in the H₂O₂ system;the formation of·SO₄^-in a persulfate system is the result of a combination of Cu（II）/Cu（III）transformation and thermal activation.Phenol is oxidized by·SO₄^-,most likely in the ortho position,and because of the intramolecular H-bond between two adjacent OH groups,the thermodynamically more stable catechins are formed.（4）Cu/Fe/SiC 1 was highest activity for the degradation of phenol,catalyst consists of Fe（III）and Cu（II）oxide,but Fe（II）and Cu（I）are the main active substances,persulfate activation by Fe-Cu composite catalyst in persulfate oxidation system to form a redox system,on the one hand,the oxidation reaction of Cu and Fe electronic involved in the formation of radicals,Fe and Cu at the same time through form a galvanic cell system can promote the Cu（II）reduction.The copper redox between Cu（II）and Cu（I）are the main factor affecting the degradation of phenol.Based on this,in the Fe/Cu-based reduction system,the concentration of Cu can maintain a relatively low equilibrium.