The degradation rates of the azo-bonds of a series of substituted azobenzenes caused by anaerobic sludge digestion were determined by measuring the biggest change of the absorption peak area of the UV-Vis spectra of t...The degradation rates of the azo-bonds of a series of substituted azobenzenes caused by anaerobic sludge digestion were determined by measuring the biggest change of the absorption peak area of the UV-Vis spectra of the anaerobic sludge system before and after degradation. The electronic structure of the molecules was calculated by using the quantum chemistry semiempirical method AM1. The research on the correlation between the biodegradability of the azo-bond and the molecular structure descriptors has led to the following results. (1) There is an obvious relationship between the degradation rate D and the difference Δq_π in π-charge density of the azo-bond. (2) The different substituents in the molecules result in a wave pattern of π-charge distribution and the increasing of the flowability of π-electron. A good flowability of the π-charge favors the reduction between electron contributing azo groups. (3) The effect of the substituents on the π-electron system depends on the electromerization of the substituents in combination with the conjugated systems.展开更多
The heterostructure Ag@WO3-x（x=0.1 or 1） composites with high selectivity for breaking azo-bond were obtained by in situ reduction of Ag2WO4. The crystal structure and morphology of Ag@WO3-x were characterized by X-...The heterostructure Ag@WO3-x（x=0.1 or 1） composites with high selectivity for breaking azo-bond were obtained by in situ reduction of Ag2WO4. The crystal structure and morphology of Ag@WO3-x were characterized by X-ray powder diffraction（XRD）, scanning electron microscope（SEM） and transmission electron microscope（TEM）. The residue solution of methyl orange（MO） after degradation was tested by gas chromatograph mass spectrometer （GCMS） to analyze the exact components. The results indicate that the products after degradation are N,N-dimethylaniline, N,N-dimethyl-p-phenylenediamine and sulfanilic acid. This is caused by specific breaking of azo-bond in MO. The azo-bond breaking of MO by Ag@WO3-x could occur in dark without any light illumination. Therefore, we proposed a possible mechanism for this azo-bond breaking reaction based on the reaction condition and results.展开更多
文摘The degradation rates of the azo-bonds of a series of substituted azobenzenes caused by anaerobic sludge digestion were determined by measuring the biggest change of the absorption peak area of the UV-Vis spectra of the anaerobic sludge system before and after degradation. The electronic structure of the molecules was calculated by using the quantum chemistry semiempirical method AM1. The research on the correlation between the biodegradability of the azo-bond and the molecular structure descriptors has led to the following results. (1) There is an obvious relationship between the degradation rate D and the difference Δq_π in π-charge density of the azo-bond. (2) The different substituents in the molecules result in a wave pattern of π-charge distribution and the increasing of the flowability of π-electron. A good flowability of the π-charge favors the reduction between electron contributing azo groups. (3) The effect of the substituents on the π-electron system depends on the electromerization of the substituents in combination with the conjugated systems.
基金Supported by the National Natural Science Foundation of China（No.21371066）.
文摘The heterostructure Ag@WO3-x（x=0.1 or 1） composites with high selectivity for breaking azo-bond were obtained by in situ reduction of Ag2WO4. The crystal structure and morphology of Ag@WO3-x were characterized by X-ray powder diffraction（XRD）, scanning electron microscope（SEM） and transmission electron microscope（TEM）. The residue solution of methyl orange（MO） after degradation was tested by gas chromatograph mass spectrometer （GCMS） to analyze the exact components. The results indicate that the products after degradation are N,N-dimethylaniline, N,N-dimethyl-p-phenylenediamine and sulfanilic acid. This is caused by specific breaking of azo-bond in MO. The azo-bond breaking of MO by Ag@WO3-x could occur in dark without any light illumination. Therefore, we proposed a possible mechanism for this azo-bond breaking reaction based on the reaction condition and results.
