Preparation Of Cathodes Based On Carbon Aerogels Composites Derived From Cellulose Fiber And Study On Degardation Of Gemfibrozil With Electro-fenton Process

At present,the electrochemical advanced oxidation process（EAOPs）has attracted more and more attention due to its application potential of completely removing refractory organic pollutants in water.Homogeneous/heterogeneous Electro-Fenton process（EF/HEF）is EAOPs based on Fenton reaction,which is environmentally friendly,stable and efficient.Therefore,it is one of the most widely used EAOPs in the treatment of new pollutants in water.At present,there are some problems in EF technology,such as low oxygen utilization rate,low current efficiency and high cost.The cathode material is the key to solve the above problems.Therefore,the development and design of an economic and efficient cathode material with good comprehensive performance is the research focus of electro Fenton water treatment technology.Cellulose derived carbon aerogels（CCA）have been selected as substrates for the study of Fenton cathode materials because of their rich material sources,rich pore structure,controllable surface chemistry and good electrical conductivity.And then,Fe^II/Fe^III LDH-CCA cathode materials were prepared.In this paper,Rhodamine B（Rh B）was used as a model compound,and response surface methodology was used to optimize the preparation process.Combined with electrochemical performance test and material characterization,the effects of preparation process parameters on the electrocatalytic oxidation performance of the material were systematically investigated;Fe^Ⅱ/Fe^ⅢLDH-CCA was studied with Gemfibrozil（GEM）as the target pollutant The removal efficiency and degradation mechanism of the cathode material LDH-CCA for GEM were studied,and the actual operation efficiency of the electro Fenton system was evaluated.In this paper,CCA was prepared from cheap and easily available natural cellulose by multi-step method.Fe^Ⅱ/Fe^ⅢLDH-CCA was prepared by hydrothermal growth of Fe^Ⅱ/Fe^ⅢLDH)on CCA substrate.Rh B was used as a model pollutant to investigate the relationship between the preparation process variables(cellulose content C_cel,carbonization temperature T_c and catalyst growth concentration C_cata)and the electrocatalytic oxidation performance of Fe^Ⅱ/Fe^ⅢLDH-CCA.According to the statistical model,the optimal preparation conditions were cellulose content C_cel=5 wt%and carbonization temperature Tc=850℃.Under this condition,the removal rate of Rh B in 180 min was more than 85%,and the electrocatalytic oxidation performance of the material reached the optimal level,which was recorded as 5-B-Ⅲ.Field emission scanning electron microscopy（SEM）,X-ray diffraction（XRD）,X-ray photoelectron spectroscopy（XPS）,nitrogen adsorption desorption curve,Fourier transform infrared spectroscopy（FT-IR）and Raman spectroscopy（Raman）were used to study the effect of alkali urea on Fe^Ⅱ/Fe^ⅢThe LDH-CCA material introduces 1%self doped N elements and abundant oxygen functional groups,and the degree of graphitization of the carbon aerogels was high,which improved the ability of the carbon aerogels to utilize oxygen in the solution and promotes the rate of 2e^-oxygen reduction reaction.The main components of the surface catalyst were Fe OOH and Fe₂O₃.The growth of the catalyst layer had a limited effect on the structural characteristics of the material,but had a significant effect on the electrocatalytic performance of the material.The optimized 5-B-ⅢFe^Ⅱ/Fe^ⅢLDH-CCA material was used as the electro-Fenton cathode to remove the target pollutant GEM.The results showed that the GEM removal curve of Fe^Ⅱ/Fe^ⅢLDH-CCA in 60 min conformed to pseudo first order kinetics,and the initial p H₀,current density i and oxygen flux Q had significant effects on the GEM removal efficiency.The optimal experimental conditions were p H₀=3.78,Q=200 m L/min,i=60 m A,T=35℃.It was proved that the material has good stability and reusability.After 8 cycles,the removal rate of GEM still reached96.9%,and the leaching content of Fe²⁺was less than 130.1μg/L.Under the optimal experimental conditions,GEM was completely mineralized after 8h electrolysis,and the mineralization current consumption decreased with the decrease of current density.The mechanism of Electro-Fenton degradation of GEM showed that the contribution of anodic oxidation and adsorption to the removal of GEM can reach 49.7%,and the active group is hydroxyl radical·OH,which is mainly produced by heterogeneous electro-Fenton on the cathode surface.The degradation path of GEM was analyzed.It was found that the aromatic intermediates were basically adsorbed on the cathode plate and gradually cracked.The aromatic ring opening products and broken side chain intermediates diffused into the solution and were completely mineralized into the final products CO₂ and H₂O.These results showed that Fe^Ⅱ/Fe^ⅢLDH-CCA has obvious effect on the removal of toxicity of GEM wastewater.