Effect of Sodium Chloride and Thiourea on Pollutant Formation during Combustion of Plastics

Thermogravimetric analysis of the co-combustion of coal and polyvinyl chloride

Coal gangue has the shortcomings of low calorific value and refractory burnout, while polyvinyl chloride has the advantages of a long combustion process and high calorific value. In order to make up for these shortcomings of coal gangue, the possibility of a treatment method based on co-combustion of coal gangue with polyvinyl chloride, which can be centrally recovered from municipal solid waste, is proposed. In order to analyze the combustion effect of a mixture of these two substances, experimental samples were prepared by mixing these two substances in three different ratios, and they were tested by thermogravimetric analysis. The experimental results were compared, analyzed and evaluated. The effects of the proportion of polyvinyl chloride in the mixture on the temperature parameters, activation energy, and interaction during co-combustion were analyzed. In order to analyze the interaction during co-combustion of the two, a coupling analysis method for mixed combustion is presented, and the effectiveness of this method is verified by comparing with the correlation analysis results of co-combustion. The results show that co-combustion can mitigate the ignition difficulty and burnout of coal gangue. When the proportion of polyvinyl chloride in the mixture was increased from 20% to 80%, the maximum weightlessness rate of the first stage rapidly increased from 4.5%/min to 15.6%/min; however, that of the second stage slowly increased from 3.7%/min to 4.2%/min. A 20% proportion of polyvinyl chloride showed the most significant promotion of co-combustion, with a maximum coupling coefficient of 0.00318, which was 1.11 and 1.35 times greater than that of 50% and 80% proportions, respectively. Co-combustion can reduce the activation energy of coal gangue during the initial and end stages. Therefore, co-combustion is helpful to improve the problems of low calorific value and refractory burnout of coal gangue.

Seasonal profiles of atmospheric PAHs in an e-waste dismantling area and their associated health risk considering bioaccessible PAHs in the human lung

Due to the development of the economy, electronic waste (e-waste) has become a new global problem and e-waste dismantling processes are an important source of air pollution. Among the pollutants emitted, polycyclic aromatic hydrocarbons (PAHs) are a severe concern because of their carcinogenic and mutagenic properties. However, few studies have investigated the atmospheric PAHs generated by e-waste dismantling in a specific region, especially the PAH levels throughout the year. Thus, we assessed the effects of PAHs on the local air quality by sampling the total suspended particulates (TSP), PM₁₀, PM_2.5, and gaseous phase from an e-waste dismantling area and a control site during four seasons. The TSP, PM₁₀, and PM_2.5 concentrations were measured as 84.8-414, 70.7-302, and 57.1-204 μg m^-3, respectively, in this area, and those of three types of particulate bound-PAHs and gaseous phase PAHs were 2.6-16.1, 2.2-15.1, 1.9-14.6, and 20.1-72.8 ng m^-3, respectively. The pollutant levels were higher in the spring and winter than those in the summer and autumn. The PAH sources were identified by diagnostic ratio approaches and principal component analysis. E-waste dismantling was identified as the major source of PAH pollution within this area, where approximately 82.4% of the PAHs was attributed to e-waste dismantling at an industrial park (EP site). Among the sites sampled, the pollutant levels and cancer risk were highest at the EP site, and they could pose a cancer risk for humans, although only the bioaccessible PAHs in human lungs were considered. In particular, infants had a higher health risk than adults, thereby suggesting that air pollution with PAHs is a concern in this area. This study provides clear evidence of the requirement for control measurements of e-waste dismantling processes.