Catalytic Degradation Of Organic Pollutants And Activity-enhanced Mechanism By Heterogeneous Metal Phthalocyanines

Water is very important for us in everyday life and in the industrial development,occupying an irreplaceable position.However,we influence natural environment,to a large extent,and the problem of water pollution arises along with the rapid development of industry.Contaminated water contains a large number of organic pollutants,such as antibiotics,dye and chlorinated aromatic compounds.These pollutants have caused serious damage to the water environment.Moreover,once these polluted water enters the river,they will enter the human body through farmland irrigation,crop absorption and so on,which directly threaten the health of human beings and other organisms.It is imminent to study and design a set of clean and efficient water pollution treatment.In many of the advanced oxidation technology,peroxymonosulfate?PMS?attracted more and more attention,because of its strong oxidizing ability and in the condition of high pH still having high activity.Cobalt catalysts have been extensively studied for their high efficiency in activation of PMS.However,homogeneous cobalt catalysts are prone to cause heavy metal pollution,and have other defects such as cobalt removal in cobalt catalyst.Therefore,this paper is based on improving the catalytic activity of non-cobalt catalyst.On the one hand,a good photosensitive metal phthalocyanine catalyst have been explored,making full use of sunlight and improving the utilization efficiency of PMS.On the other hand,the suitable carrier?grapheme?is selected to construct a highly efficient and stable heterogeneous iron catalyst to improve the activity of the catalyst.In our study,it is important to research on basic theoretical problems,such as catalytic performance,stability and cyclicity of catalytic system/PMS in degradation of organic pollutants carbamazepine?CBZ?process.The main research content is divided into the following two parts:Iron hexadecylchlorophthalocyanine(FePcCl₁₆)was prepared by liquid phase method,which was characterized by Fourier Transform infrared spectroscopy?FTIR?,X-ray photoelectron spectroscopy?XPS?and Ultraviolet–visible spectroscopy?UV-Vis?.It was confirmed that the obtained green powder is FePcCl₁₆.The experiment selected CBZ as the main substrate,PMS as oxidant,to study the photocatalytic activity and stability of the catalyst in the sunlight irradiation conditions.FePcCl₁₆/PMS/Sunlight system can degrade CBZ of⁹8%within60 min,and the degradation rate constant?0.082?is 9.7 times higher than that of FePcCl₁₆/H₂O₂/Sunlight system(9.77×10^-4),revealing that FePcCl₁₆/PMS/Sunlight system has more significant potential in wastewater treatment.In addition to the rapid degradation of CBZ,FePcCl₁₆/PMS/Sunlight system can also quickly and efficiently degrade other dyes and antibiotic drug contaminants.Moreover,it was found that FePcCl₁₆ also had excellent stability and reproducibility,and there was no obvious reduction in activity by 20 cycles.Electron paramagnetic resonance?EPR?,gas chromatography-mass spectrometry and photocatalytic activity experiment analysis shows that Fe?IV?=O species,singlet oxygen?¹O₂?,hydroxyl and sulfate radicals?·OH,SO₄·^-?are the main active species in the catalytic oxidation of CBZ.Density functional theory?DFT?calculations exhibits that the electronic cloud for excited state FePcCl₁₆*is transferred from the porphyrazine ring and peripheral substituents to the central Fe atom and its axial position.The main degradation intermediates and possible degradation pathway of CBZ were proposed by ultra-performance liquid chromatography and high-resolution mass spectrometry?UPLC Synapt G2-S HDMS?.This study provides efficient catalytic oxidation support for wastewater treatment.In order to build a more efficient catalytic system,we selected graphene as a carrier because of its strong adsorption and excellent electrical conductivity.FePcCl₁₆ was loaded onto graphene by a simple adsorption method to prepare GR/FePcCl₁₆ catalyst.The structure and constituent elements for samples were characterized by UV-vis,FTIR and BET.The activity of GR/FePcCl₁₆/PMS in the catalytic oxidation of CBZ and the stability of the catalyst were investigated.Electron paramagnetic resonance,gas chromatography-mass spectrometry and capture experiment?MA and TBA as capture agent?were used to detect the possible active species and speculate the possible catalytic mechanism.The results showed that the FePcCl₁₆was successfully loaded on GR,getting the catalyst GR/FePcCl₁₆ by some test method of SEM,FTIR and BET.The system could degrade CBZ effectively by main active species without sunlight product and CBZ removal from solution reached nearly 99.9%within 25 min.It is obvious that the catalytic degradation efficiency of the GR/FePcCl₁₆/PMS catalytic system is higher than that of the FePcCl₁₆/PMS catalytic system.The catalytic effect of GR/FePcCl₁₆/PMS catalyst system is the best under acidic conditions.Besides,the influence of other substances on the catalytic system can be negligible in water treatment.Electron paramagnetic resonance,gas chromatography-mass spectrometry and capture experiment?MA and TBA as capture agent?shows that Fe?IV?=O species,singlet oxygen?¹O₂?,hydroxyl and sulfate radicals?·OH,SO₄·^-?are the main active species in the catalytic oxidation of CBZ.