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Nanobioremediation
Published in Pradipta Ranjan Rauta, Yugal Kishore Mohanta, Debasis Nayak, Nanotechnology in Biology and Medicine, 2019
Manoj Kumar Enamala, P. Divya Sruthi, Silpi Sarkar, Murthy Chavali, Induri Vasavi, Chandrashekar Kuppam
Wastewater treatment is a complex process, taking into consideration various factors like quality standards, cost, and efficiency. In this regard, several researchers have found that iron nanoparticles (nano-sized zero-valency ions, otherwise known as NZVI) and polymer-coated nanoparticles play a significant role in the removal of heavy metals like Cr(VI), As(III), etc. The removal of heavy metals using this NZVI principle has been done using various media, showing that it has an outstanding ability to remove heavy metals from contaminated sources of water. Carbon tetrachloride, pentachlorobenzene, chloro- and dichlorobenzene, chloromethane, acid red, and acid orange are a few types of pollutants being released and also treated with the nano iron technology or NZVI technology.
Air Sampling
Published in Martin B., S.Z., of Industrial Hygiene, 2018
Membrane filters are made from mixed cellulose ester (MCE), polyvinyl chloride (PVC), or polytetrafluoroethylene (PTFE). Since most particle collection takes place at or near the surface, membrane filters are useful for applications where the collected particles will be examined under a microscope. MCE membrane filters dissolve easily with acid. Hence, they are used for collection of asbestos fibers, and also used for collection of metals and metal fumes for atomic absorption analysis. Pore sizes of 0.45 mm and 0.8 mm are the most commonly used. Table 4.9 lists selected compounds that are collected on MCE filters. PVC membrane filters are used for sampling carbon black, respirable silica, total and respirable dusts, and zinc oxide. Table 4.10 lists selected compounds that are collected on PVC filters. PTFE membrane filters come in a variety of pore sizes, 1 mm, 2 mm, and 5 mm, and are used for pesticides, alkaline dusts, and many other compounds. Selected compounds that are collected on PTFE filters include polycyclicaromatic hydrocarbons (e.g., anthracene, benzo(a)pyrene, chrysene, etc.); coal tar pitch volatiles; alkaline dusts; diborane; paraquat; methyl arsonic acid; pentachlorobenzene; o-toluidine; thiram; 1,2,4-trichlorobenzene; and warfarin.
Physical Properties of Individual Groundwater Chemicals
Published in John H. Montgomery, Thomas Roy Crompton, Environmental Chemicals Desk Reference, 2017
John H. Montgomery, Thomas Roy Crompton
Biological. In activated sludge, only 1.5% of the applied hexachlorobenzene mineralized to carbon dioxide after 5 days (Freitag et al., 1985). Reductive monodechlorination occurred in an anaerobic sewage sludge, yielding 1,3,5-trichlorobenzene as a major product. Other compounds identified include pentachlorobenzene, 1,2,3,5-tetrachlorobenzene, and dichlorobenzenes (Fathepure et al., 1988). In a 5-day experiment, [14C]hexachlorobenzene applied to soil–water suspensions under aerobic and anaerobic conditions gave 14CO2 yields of 0.4 and 0.2%, respectively (Scheunert et al., 1987). In an enrichment culture derived from a contaminated site in Bayou d'Inde, Louisiana, hexachlorobenzene underwent reductive dechlorination. The major degradation pathway was hexachlorobenzene → pentachlorobenzene → 1,2,3,5-tetrachlorobenzene → 1,3,5-trichlorobenzene → 1,3-dichlorobenzene. Low concentrations of 1,2,4,5-tetrachlorobenzene, 1,2,4-trichlorobenzene, and 1,4-dichlorobenzene were also detected. The maximum dechlorination rate, based on the recommended Michaelis–Menten model, was 52 nM/day (Pavlostathis and Prytula, 2000).
Emission characterization of PeCB, HCB and their correlation in fly and bottom ashes from various thermal industrial processes in Northern Vietnam
Published in Human and Ecological Risk Assessment: An International Journal, 2021
Nguyen Thi Hue, Thi Phuong Mai Nguyen
Hexachlorobenzene (HCB) and pentachlorobenzene (PeCB) are group of unintentionally produced persistent organic pollutant (U-POP) categorized in the Annex C of the Stockholm Convention. Their characteristics are persistence, bioaccumulation, toxicity, and long range environment transport potential (Meijer and Ockenden 2003; Shen et al. 2004). Some researchers reported that HCB and PeCB have formed and emitted from waste incinerator (Li et al. 2015; Zhang et al. 2011), metallurgical production (Antunes et al. 2012; Li et al. 2014; Nie et al. 2011, 2012a, 2012b), cement production (Y. Q. Li et al. 2016) and coal fired power plants (Liu et al. 2009, 2013). In the mid-1990s, Bailey (2001) calculated global HCB emission as approx. 23,000 kg/yr with a range of 12,000 kg/yr–92,000 kg/yr based on summary of HCB emissions in the U.S. and Canada. The ICCA/WCC (2007) estimated the annual global emission of PeCB of 85,000 kg/yr based on the U.S. Toxics Release Inventory (U.S. EPA 2007). These studies indicated that emissions of PeCB and HCB was higher than that of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), dioxin-like polychlorinated biphenyl (dl-PCB) in flue gas and fly ash, and HCB are the major constituents of fly ash.
Antioxidant response mechanism of freshwater microalgae species to reactive oxygen species production: a mini review
Published in Chemistry and Ecology, 2020
Adamu Yunusa Ugya, Tijjani Sabiu Imam, Anfeng Li, Jincai Ma, Xiuyi Hua
The incessant discharge of organic pollutants into the aquatic environment is worrisome due to the persistent nature of this pollutants and the effect they have on the aquatic biotic community [57,58]. The ROS released into freshwater environment by freshwater microalgae oxidised organic pollutants leading to the degradation of these organic pollutants and formation of inorganic carbon and water which is utilised by the freshwater microalgae [59]. The ROS produced by freshwater microalgae tend to facilitate the decomposition of organic compound because it readily breakdown organic compounds into CO2, CO32- and H2O as shown in equation (3).ROS have generally been shown by Hayyan et al. [9] to degrade persistence alkyl halide such as trichlorobenzene, tetrachlorobenzene, hexachlorobenzene, pentachlorobenzene, decachlorobenzene and heavy polychlorobenzenated biphenyl (PCBs) signifying the potentiality of the ROS produced by freshwater microalgae to be able to degrade this persistence organic halides. The ROS produced by freshwater microalgae could also be useful in the degradation of pollutants containing sulfur due to the ability of ROS to desulfurise thiocarbonyl compounds such as thioamides, thioureas, and thiouracils to carbonyl compounds [60].