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Hyper-crosslinked Polymers
Published in Inamuddin, Mohd Imran Ahamed, Rajender Boddula, Porous Polymer Science and Applications, 2022
Belén Arcentales-Vera, Lisandra Bastidas, Moises Bustamante-Torres, Paul Maldonado Pinos, Emilio Bucio
Aromatic heterocyclic monomers can also be used as building blocks to form HCPs by the knitting strategy, as demonstrated by Luo et al. (2012). They synthesized microporous heterocyclic polymers from thiophene, pyrrole, and furan under the typical reaction conditions (FDA, FeCl3, in DCE). Despite having relatively low surface areas, these polymers showed superior adsorption selectivity and capacity due to heteroatoms’ presence in the networks. Moreover, the knitting strategy has also been successfully applied to fused-heterocyclic rings (e.g., carbazole, triazine (Zhu et al. 2014), indole, benzothiophene, dibenzothiophene, benzofuran, dibenzofuran (Saleh et al. 2014), and tricarbazolyltriptycene (Zhai et al. 2016)), and to inorganic group polyhedral oligomeric silsesquioxane (POSS) (S. Wang et al. 2015) to yield hyper-crosslinked networks with predominantly microporous structures.
Environmental Impacts of Biofuel-Fired Small Boilers and Gasifiers
Published in Mateusz Szubel, Mariusz Filipowicz, Biomass in Small-Scale Energy Applications: Theory and Practice, 2019
Jozef Viglasky, Juraj Klukan, Nadezda Langova
Other toxic compounds: It is well established that extremely toxic dioxins and furans (polychlorinated dibenzodioxins [PCDDs], or simply dioxins, are a group of polyhalogenated organic compounds that are significant environmental pollutants; and polychlorinated dibenzofurans [PCDFs] are a family of organic compounds with one or several of the hydrogens in the dibenzofuran structure replaced by chlorines) are formed during most combustion and gasification processes when some chlorine (Cl) is present. Under normal operating conditions the concentrations of these compounds in wood-fired units are extremely small, although pesticide-treated wood and waste materials can provide the source of Cl necessary for their formation. A close-coupled IGCC (integrated gasification combined cycle) system normally provides satisfactory operating conditions for thermal destruction of these compounds and it is generally believed that they do not present any problem, though very few data exist to support this.
Myths About Toxicology and the Environment
Published in Kletz Trevor, Dispelling Chemical Engineering Myths, 2017
The dioxins are a group of 210 compounds made by replacing one or more of the hydrogen atoms in dibenzodioxin or dibenzofuran by chlorine atoms. The most toxic of all is 2,3,7,8-tetrachloro-dibenzodioxin (2,3,7,8-TCDD). Seventeen of the others are also toxic, most to a much smaller extent, and the remaining 192 are nontoxic. Some of the literature on dioxins does not make it clear whether it is referring to 2,3,7,8-TCDD or to the group as a whole, and at one time it was not possible for analysts to distinguish between them. Today it is possible to make this distinction and to detect as little as one part per trillion, that is, 1 gram in a million tons. This is one reason for public concern about dioxins (and other toxins). When we are told that none has been detected, we relax. When analysts improve their methods and now detect even trace amounts, we start to worry, even though the amount is equivalent to only a few drops in a swimming pool.
Formation of Polycyclic Aromatic Hydrocarbons (PAHs) and Oxygenated PAHs in the Oxidation of Ethylene Using a Flow Reactor
Published in Combustion Science and Technology, 2022
Shunsuke Suzuki, Shota Kiuchi, Koichi Kinoshita, Yoshinaka Takeda, Kotaro Tanaka, Mitsuharu Oguma
The previous sections have considered the behavior of MAHs, PAHs, and OPAHs formed in a flow reactor system when several experimental parameters were varied. As we are also interested in the formation of OPAHs, their probable formation pathways are discussed herein. Some clues were provided by the experimental results in this study. For example, the fact that OPAHs achieved maximum concentrations as a function of gas temperature suggests that OPAHs were formed during the oxidation reactions of parent PAHs. This is because the oxidation/degradation reactions of the parent PAHs may be quite rapid at high temperatures, but too slow to form OPAHs at low temperatures. The experimental results enabled measurement of one type of alcohol with a single aromatic ring and two types of furans and ketones with multiple rings. Because phenol formation channels have already been stated, their discussions are omitted here. Hence, the candidate growth pathways for two furans, benzofuran and dibenzofuran, and two ketones, 9-fluorenone, and benzanthrone are discussed.
Evaluation of pilot scale in-vitro and ex-situ hydrocarbon bioremediation potential of two novel indigenous strains of Bacillus vallismortis
Published in Bioremediation Journal, 2020
Manisha Basumatary, Suman Das, Madhurjya Gogoi, Indukalpa Das, Dipika Charingia, Debajit Borah
Vehicular growth has been increased in recent times drastically with the advent of urbanization (Vijayalakshmi and Krishna 2019). Motor oil which is popularly known as engine oil is a major component used in automobile engines to run them smoothly. Frequent release of used engine oil during servicing of automobile engines or due to illegal dumping poses a great threat to the local environment as it is less volatile as compared to other form of petroleum fuels and remains in the soil for longer duration of time (USEPA 2015). The severity of petroleum contamination may be well understood by considering the fact that more than 700 tonnes of oil spillage by oil tankers had taken place since the year 1970–2019 in oceans across the globe (Oil Tanker Spill Statistics 2019). Whereas, the biggest oil spill in history took place in the land of Lakeview Gusher, California during 1910–1911 which released 9 million barrels of crude oil and lasted for 18 months (Roser 2013). India witnessed one of the major oil spillages on the coast of Chennai in the year 2017 which caused the release of 251 MT of petroleum oil in the Bay of Bengal (Report pegs Ennore oil spills at 251 tonnes 2017). Very recently, on 27 May of this year a sudden and uncontrolled release of gas occurred from an oil well near Dibru Saikhowa National Park in Assam causing oil spillage in the nearby area (Guha 2020). The major components of such oil are basically cyclic alkanes, polyaromatic hydrocarbons (PAHs), normal and cyclic paraffin, naphthalene, fluorine, benzene, dibenzofuran, dinaphthenebenzene, dibenzanthracene, etc. (Koma et al. 2001). Such components may lead to soil toxicity followed by inhibition of plant growth (Tang et al. 2011). Moreover, cyclic alkanes and polyaromatic hydrocarbons are also responsible for eye and skin irritation, inflammation, cardiovascular diseases, lung diseases and may also lead to skin, lung, bladder, and gastrointestinal cancer (Lawal 2017).
Comprehensive target analysis of micropollutants in soil at debris storage sites of the Kumamoto earthquake
Published in Soil and Sediment Contamination: An International Journal, 2020
Yuki Matsuo, Haruhiko Nakata, Tetsuro Agusa, Takashi Miyawaki, Kiwao Kadokami, Katsuhisa Sato, Misato Matsumoto, Taiki Higuchi, Kou Nishimuta, Noriko Ryuda, Hideki Miyamoto, Tomokazu Haraguchi, Daisuke Ueno
The initial CTA-AIQS survey suggested that pesticides and PAHs from waste wood, and plasticizers from waste electric equipment were the characteristic organic micropollutants in soils below stored debris (Figure 2a). It was obvious that plasticizers detected at A2 and C3 (Table 1) were derived from plastics used in waste electric equipment. Source of PAHs and related chemicals (biphenyl, carbazole, dibenzofuran, dibenzothiophene, etc.) detected in soil under waste wood in A1, B1, and C2 could be pyrogenic and petrogenic (including coal-tar paint) origins. In contrast, it was unclear why the group of pesticides (insecticides, fungicides, and herbicides) was detected in those samples of soil under waste wood. To try to identify the source of those chemicals, we summarized in Figure 3 the profiles of the pesticides that were detected (Table S3 summarizes the individual concentrations and uses of those pesticides). The major categories of agricultural chemicals were insecticides (chlordane, chlorpyrifos, and fipronil) and fungicides (iprobenfos, isoprothiolane, and propiconazole). The herbicides thiobencarb, bromobutide, and mefenacet were also detected in the soil under waste wood. Among the pesticides, several insecticides and fungicides have been used as wood preservatives and termiticides in Japan (JWPA 2006). Table S4 summarizes the chemicals used as wood preservatives and termiticides in Japan. It was reported that pentachlorophenol (PCP), chlordanes, and polychloronaphthalenes (PCNs) which used as wood preservatives were detected in waste timber (woods) collected in Japan (Koyano et al. 2019). Soil contamination by dieldrin and pentachlorophenol (PCP), which leach from timbers treated with wood preservative, has also been reported (McNeili 1990). Those results suggested that the waste wood debris included timbers used as building materials that had been treated with wood preservatives and termiticides; those chemicals then leached from the wood after it was piled together at debris storage sites, and they contaminated the soil at those locations.