Study On The Migration And Transformation Process Of Bromine Element In The Process Of Combustion And Pyrolysis Of Brominated Flame Retardants

With the rapid development of science and technology,the rapid elimination of electronic and electrical equipment has made electronic waste the fastest growing solid waste in the world.Due to the complex composition of e-waste,improper disposal in the recycling process will pose a huge threat to the human body and the environment.How to realize its harmless treatment and resource utilization is a huge challenge currently facing.The incineration method is widely used in the treatment of municipal waste,but there are few related researches on the treatment of electronic waste.Bromine flame retardants are common in electronic waste,and a large amount of gaseous bromination will be generated during the combustion process The substance will be released into the environment while corroding the equipment,which is harmful to human health and the surrounding environment as usual.Based on this background,this paper studies the migration and transformation of bromine during pyrolysis and combustion of bromine flame retardants.In this paper,three typical brominated flame retardants,tetrabromobisphenol A,hexabromocyclododecane,and decabromodiphenyl ether,are selected as the research objects.The atmosphere of the thermal decomposition reaction is regulated and tested in a tube furnace.Study on the decomposition mechanism of brominated flame retardants in heat treatment.First,the thermal decomposition products of three brominated flame retardants are analyzed,including residues,condensable products and non-condensable products.The research results show that changing the thermal decomposition atmosphere will significantly increase the bromine content in non-condensable products and reduce The yield of condensables.When oxygen is contained in the thermal decomposition atmosphere,the bromine content in the condensables decreases and the bromine content in the non-condensables increases.Secondly,Fourier infrared spectroscopy and XPS analysis were carried out on the thermal decomposition residues of the three brominated flame retardants.The infrared spectra before and after the thermal decomposition showed that the same existed on the surface of the solid product after pyrolysis and combustion.Functional groups,the same elements are also detected in the XPS spectrum,and according to the peak fitting of C1 s and O1 s,we can see that the properties of brominated flame retardants are roughly the same as the products of pyrolysis and combustion,but in the presence of oxygen The thermal decomposition of brominated flame retardants is more thorough,and the fixing rate of bromine on the residual carbon is lower.Finally,TG-FTIR-MS analysis was performed on the three brominated flame retardants.According to the TG-DTG curve,it was found that the thermal decomposition curves of the three brominated flame retardants during the combustion and pyrolysis process have changed.In the presence of oxygen,the degree of thermal decomposition of brominated flame retardants is higher.In the FTIR curve,we can also observe that in the presence of oxygen,the observed absorption peak of CO2 is obviously stronger than the pyrolysis process,which indicates that the presence of oxygen promotes the thermal decomposition of brominated flame retardants.Secondly,we observed the ion fragments of the bromine-containing substance MS.Although fragments with the same mass ratio were found during combustion and pyrolysis,the content of these fragments released by thermal decomposition under different atmospheres is not the same,indicating that oxygen Existence affects bromine-containing compounds released during thermal decomposition of brominated flame retardants.The thermal decomposition mechanism of three brominated flame retardants is proposed.