Research On The Detection And Emission Reduction Of Brominated Dioxins In The Process Of E-waste Treatment

With the development of technology,electronic products have been continuously updated,and the output of electronic waste has risen sharply.The improper treatment and disposal of e-waste has led to the discharge of a large number of toxic pollutants into the environment,among which the problem of brominated dioxins is particularly prominent.Therefore,it is of great significance to research on the formation of PBDD/Fs in the process of electronic waste treatment and disposal.In this paper,the following three aspects of work have been completed on the PBDD/Fs pollution caused by e-waste treatment and disposal.Firstly,this paper established the analysis and detection method of PBDD/Fs in electronic waste by referring to the standard analysis method of PCDD/Fs and the method reported in the literature.The results showed that the detection limit of the instrument was0.012pg~0.064pg,the average recovery of internal standard was 56%~83%,and RSD was4.26%~10.38%,which indicates that the recovery and accuracy of the method were good,and it was suitable for the analysis of PBDD/Fs in electronic waste.Secondly,brominated flame retardants are the main source of PBDD/Fs because of their wide application in electronic and electrical products.In this paper,the plastic casing of TV set,washing machine plastic casing,and the waste circuit boards were selected respectively,and their original PBDD/Fs were tested and analyzed by the established analysis and detection method of PBDD/Fs in the e-waste.The content of PBDD/Fs in the TV plastic set,washing machine plastic case,and the circuit board samples were 4.58 pg TEQ/g,4.33 pg TEQ/g,4.46 pg TEQ/g,respectively.At the same time,we collected and analyzed the air and exhaust samples of Changzhou Xiangyu Resources Recycling Co.,Ltd.The toxic equivalent of K1,K2 and K3 in ambient air samples were 0.015,0.012 and 0.010 pg TEQ/m~3,respectively.The toxic equivalent of F1,F2,F3 and F4 in exhaust samples were 0.38,0.23,0.37,0.43 pg TEQ/m~3 respectively.The concentration levels of PBDD/Fs in the air samples and exhaust samples collected by the experiment are much lower than those reported in the literature,which indicates that the standardized e-waste disassembly has little impact on the surrounding environment.Finally,the tube furnace was used as the electronic waste incineration device to carry out the incineration experiment of electronic waste in this paper.By controlling the temperature and oxygen content in the incineration process,explores its influence on the formation of PBDD/Fs generation.The results show that the PBDD/Fs produced by incineration between500°C and 900°C decreases with the increase of temperature,reaching the highest value of2255.78 pg TEQ/g at 500°C and the lowest value of 597.91 pg TEQ/g at 900°C.It is due to the decomposition of PBDD/Fs with the increase of temperature,the production of PBDD/Fs is continuously reduced.The PBDD/Fs produced by incineration increased first and then decreased with the increase of oxygen concentration between 10%and 50%.When the oxygen concentration was below 30%,the PBDD/Fs production was positively correlated with the oxygen concentration.The PBDD/Fs production reached the maximum value of1300.39 pg TEQ/g when the oxygen concentration was 30%.With the increase of oxygen concentration,the production of PBDD/Fs decreases gradually.At this time,oxygen mainly plays the role of improving combustion efficiency and oxidizing the generated PBDD/Fs.Therefore,in order to reduce the generation of PBDD/Fs,incineration of electronic waste should be carried out under high temperature and low oxygen conditions.