China
Africa
Explore chapters and articles related to this topic
Pollution Risk Factors
Published in Daniel T. Rogers, Environmental Compliance and Sustainability, 2019
Atmospheric contaminants vary dramatically and originate from anthropogenic and natural sources. Anthropogenic sources are most prevalent in urban areas, and include stationary emitters such as manufacturing facilities, power generating plants, dry cleaners, and mobile emitters such as automobiles, trucks, buses, and airplanes (USEPA 2018). Natural sources include particles from volcanic eruptions, biological decay, forest fires, and pollen. Volatile organic compounds (VOCs) are also emitted by plants and trees. As an example of atmospheric contaminant variety, consider the VOC isoprene emitted by some tree species (e.g., oaks) (Sharkey et al. 2008). Isoprene is carcinogenic to humans if inhaled as a concentrated vapor within a closed space (USEPA 2002b), but concentrations in the atmosphere do not reach levels of concern.
Biofuel and Biochemical Production by Photosynthetic Organisms
Published in Kazuyuki Shimizu, Metabolic Regulation and Metabolic Engineering for Biofuel and Biochemical Production, 2017
Isoprene (C5H8) is a volatile compound and utilized in the synthesis of rubber, and it is also a repeating unit of many natural products (isoprenoids) such as vitamin A and steroid hormons (Ruzicka 1953). Isoprene is naturally produced by plants (Sharkey and Yeh 2001), and by heterotrophic bacteria such as Bacillus cereus, Pseudomonas aeruginosa, and E. coli (Kuzma et al. 1995, Fischer et al. 2008, Stephanopoulos 2008). Isoprene is easily evaporated from the culture broth, and thus the toxicity to the cell can be relaxed by evaporation, where it can be trapped in the gas phase.
Terpenes and Terpenoids
Published in William J. Rea, Kalpana D. Patel, Reversibility of Chronic Disease and Hypersensitivity, Volume 4, 2017
William J. Rea, Kalpana D. Patel
The majority of isoprene produced commercially is used to make synthetic rubber (cis-polyisoprene), most of which is used to produce vehicle tires. The second and third largest uses are in the production of styrene–isoprene–styrene block polymers and butyl rubber (isobutane–isoprene copolymer).18
Photochemical impacts on the toxicity of PM2.5
Published in Critical Reviews in Environmental Science and Technology, 2022
Jialin Xu, Wenxin Hu, Donghai Liang, Peng Gao
Terpenes are mainly emitted by plants and belong to natural and biogenic VOCs (Holopainen et al., 2017). Globally, isoprene (ISO) and α/β-pinene are the first and second largest non-methane hydrocarbons among all the terpenes and play important roles in the formation of SOAs (Holopainen et al., 2017; Rohr & Annette, 2013). Isoprene has exhibited reproductive toxicity, inhalation toxicity, and carcinogenicity; however, its toxicity is weaker than its homologue, 1,3-butadiene (Anderson, 2001; Melnick et al., 1996). Exposing B6C3F1 mice to isoprene can induce testicular atrophy, lead to an increase in sister chromatid exchanges in bone marrow cells, and cause series of neoplasms; however, isoprene cannot induce chromosomal aberrations in the bone marrow cells of mice (Melnick et al., 1996). For α-pinene, epidemiological experiments and animal experiments show that it has the potential to cause respiratory and skin irritation (Rider, 2016). Also, inhalation of α-pinene or its mixture with other pinenes can cause respiratory discomfort (Filipsson, 1996; Rider, 2016). Currently, there is insufficient research to prove that α-pinene exhibits carcinogenic and genotoxic potential (Rider, 2016). Also, as VOCs are quite unstable in the atmosphere, there are very few studies that directly discuss the health risks of terpenes at normal atmospheric concentrations.
The co-pyrolysis of waste tires and waste engine oil
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2022
Junzhi Wang, Xiaowen Qi, Xinjiang Dong, Siyi Luo, Yu Feng, Mao Feng, Xianjun Guo
GC/MS characterization was used to detect the compounds present in the pyrolysis oil for qualitative and semi-quantitative. The condensable compositions were characterized. Aliphatic compouns, aromatic compounds, and cyclic compounds were observed in the pyrolysis oil. There are more than 200 compounds, which were determined by the comparision with the peaks with the NIST library. Only the compounds present at 1 wt.% and above are presented. The total ion chromatograms are shown in Figure 8. Tables 6 and 7 represent their composition and content. In many cases, the chemical compound grade was displayed instead of individual molecules because the complicated mixture composition grows into unfeasible the resolving of very similar components (Torretta et al. 2015). Table 6 shows the chemical composition of pyrolysis oil from WT, the composed mostly of benzene-substituted compounds (40.23%), most of them were derivate compounds from ethylbenzenes (9.86%) and toluene (7.34%). Saturates were mainly branched alkanes containing eight carbon atoms (7.82%). One extensive range of industrial application compound limonene (3.14%) detected is pyrolysis oil. Compared with the compounds, the chemical composition from tire and WEO co-pyrlysis changes significantly. Aliphatic compounds (21.68%) are the main components. The content of benzene-substituted compounds decreases to 14.85%. The yield of limonene increases from 2.14% to 3.99%. According to other studies, the WEO, containing C11-C40 hydrocarbons, is thermally cracked to oil products comprising mainly of C5-C30 hydrocarbons, and which are dominated by aliphatic hydrocarbons (50–71 wt.%) and significant amounts of aromatics (23–42 wt.%) (Zhang et al. 2016). This indicates cyclization and aromatization reactions may occurred during co-pyrolysis. During pyrolysis, compounds in oil break up randomly to form hydrocarbon radicals. These free radicals react with tire pyrolysis products, such as dehydrogenation, hydrogen capture, polymerization, and cyclization(Yuan, Tahmasebi, and Yu 2015). The increasing of hydrogen in pyrolysis gas is consistent with this conclusion. D-limonene in the product is an important raw material in the field of flavors and fragrances. Studies have shown that it has a good anti-cancer effect and has great recycling value (Mishra and Mohanty 2020). This provides a new idea for the preparation of D-limonene. Isoprene is one of the raw materials of synthetic rubber with a large proportion in the three catalytic cracking products (Mishra and Mohanty 2020). Styrene is one of the most important raw materials in synthetic resin and synthetic tire industry (Alvarez et al. 2019).