Electrochemical Degradation Of Amine Organic Compounds

In this paper,N,N-dimethylformamide（DMF）,a typical organic amine pollutant,was selected as the target.And the effects of these conditions on the removal rate of DMF were investigated in terms of current density,initial p H,and chlorine salt ratio.These three conditions were optimized by response surface curve method to obtain the optimal working conditions,and kinetic fitting was performed for the electrochemical oxidation experiments under the optimal conditions.The electrochemical degradation mechanism of DMF was analyzed in depth using differential electrochemical mass spectrometry（DEMS）.The products with and without the involvement of chloride ions in the electrochemical process were investigated by gas chromatography-mass spectrometry（GC-MS）,respectively,and the degradation pathways of DMF were analyzed and inferred.The following results were obtained:（1）X-ray diffraction analysis and scanning electron microscope analysis were carried out on the four electrodes,and electrochemical oxidation experiments were carried out on simulated DMF wastewater with each of the four electrodes to compare their DMF removal rates and TOC removal rates.The DMF and TOC degradation performance was in the same order as Ti/RuO₂-IrO₂>Ti/RuO₂-IrO₂-SnO₂>Ti/Ta₂O₅-IrO₂>Ti/IrO₂-Ta₂O₅-SnO₂.The Ti/RuO₂-IrO₂electrode was selected as the best working electrode.（2）A preliminary speculation on the mechanism of DMF degradation by Ti/RuO₂-IrO₂electrode was carried out.The form of oxidation was determined to be indirect by cyclic voltammetry（CV）;the reactive group with the greatest influence on DMF degradation was concluded to be the SO₄·^-by molecular probe experiments.（3）Based on the results of the single-factor experiments,the optimal conditions for the degradation of DMF were current density:40 m A/cm²,initial p H:6 and Na Cl proportion:20%.These conditions were optimized using the response surface curve method,and the significance level of the effect of each factor on the DMF removal rate was analyzed.Current Density>Na Cl Proportion>Initial p H.When the current density was 47 m A/cm²,the initial p H was 5.5 and the Na Cl proportion was 15%,the DMF removal rate had a maximum calculated value of 97.2%.（4）The actual removal rate obtained from the electrochemical experiment under the calculated optimum conditions was 97.3%,which was greater than the calculated value of 97.2%.Therefore,the above calculated conditions were found to be the best experimental conditions.The kinetic model for the degradation of DMF was fitted under these conditions and the kinetic model for the degradation of DMF was found to be consistent with pseudo first order kinetics.（5）An in situ study of the entire DMF degradation process using DEMS verified that the degradation of DMF is an indirect oxidation process and that in the presence of Na Cl,the degradation of DMF was affected by a combination of SO₄·^-as well as active chlorine species.（6）The electrochemical products of DMF with and without the presence of Na Cl were analyzed separately by GC-MS and it was found that the degradation of DMF was not thorough when no Na Cl were present and that methyl formamide was still present in the final product,while the degradation was more thorough in the presence of Na Cl.（7）The degradation pathways of DMF in the two groups with and without the presence of Na Cl were deduced separately from the GC-MS results as well as from the chemistry studied.