Dynamic Material Flow Analysis Of Polyvinyl Chloride And Its Typical Additives In China

As one of the five universal resins,polyvinyl chloride(PVC)has been used in construction,packaging,agriculture,industry and other fields with excellent performance.However,it also hides huge environmental risks and may produce environmental pollutants in various life cycle activities.Additives used in PVC,such as phthalic acid esters(PAEs)and lead salt heat stabilizers,also have strong biological toxicity.In this study,the dynamic material flow analysis and scenario analysis model of China’s PVC and its PAEs and lead salt heat stabilizers were constructed,the flows and stocks of PAEs and lead salt heat stabilizers in China’s PVC and its products from 1958 to 2019 were tracked and quantified.In addition,the future development trend of PVC and its typical additives in China’s social and economic system from 2020 to 2050 was reasonably predicted,and corresponding suggestions on resource management and pollution prevention and control were put forward.The research results have important practical guiding significance for the sustainable production and consumption of PVC and its additives.The material flow analysis found that from 1958 to 2019,the consumption,scrap and in-use stocks of PAEs and lead salt heat stabilizers in PVC and its products experienced a period of rapid development.The PVC consumption increased from 2 kt to 15572 kt at an average annual growth rate of 16.1%,and the proportion of the construction sector in the consumption structure increased from 24.8%in 1990 to 60.2%in 2019.PVC products cumulatively consumed 29235 kt of PAEs and 2373 kt of lead salt heat stabilizers(calculated by lead)respectively,and cumulatively generated 138866 kt,20658 kt and 1553 kt of PVC,PAEs and lead salt heat stabilizers(calculated by lead)post-consumer wastes respectively.By 2019,the in-use stocks of PVC,PAEs and lead salt heat stabilizers(calculated by lead)were 88905 kt,5043 kt and 818 kt respectively.The cumulative emissions of PAEs were 4456 kt,and the use stage was the largest PAE emission source,of which 78.7%came from the outdoor use of PVC roofing materials,agricultural film,wires and cables and other products,and soil was the main destination of emissions.113 kt of lead was discharged in the whole life cycle of lead salt heat stabilizer,and the processes of PVC product manufacturing,use,waste incineration and open-air incineration contributed 90 kt,1 kt,1 kt and 21 kt respectively.The results of scenario analysis show that the demand for PVC,PAEs and lead salt heat stabilizers will continue to grow as a whole,but the growth rate will slow down significantly.By 2050,the demand for the three will reach 23341～35825 kt,1749～2943 kt and 142～207 kt(calculated by lead)respectively,and the demand for building materials in downstream products is the largest.Corresponding to the growth of consumption,the scrap amount of PAEs and lead salt heat stabilizers in PVC and its products will also increase year by year in the future.From 2020 to 2050,the cumulative scrapping amount of PVC,PAEs and lead salt heat stabilizers will be 590152～691097 kt,56108～66068 kt and 4197～4773 kt(calculated by lead)respectively.PVC building materials,automobiles and other products with long service life will usher in the climax of scrapping,and their proportion in scrapped products will gradually increase.As the main contributor to the in-use stocks of PVC,PAEs and lead salt heat stabilizers,the construction sector will be the main source of relevant waste streams in the future.On the one hand,improving the recovery rate of PVC waste can reduce the production of raw PVC and its additives such as PAEs and lead salt heat stabilizer,and at the same time reduce the corresponding resource consumption and pollution emissions in the production process;On the other hand,it can reduce the emission of PAEs and lead in PVC products,with remarkable economic and environmental benefits.