The Impact of Solvents on Environment and Their Alternatives

Numerous of the chemical are affection our environment badly where Their pathways enter the air, water, and soil when they are delivered, utilized or arranged. There are products with containing hazardous environment on long-term exposure leading to many problems to the humans, animals, and environment. Where there is a latter of three consumer application of all solvents that can release to the atmosphere, in industrial application solution solvents can be installed to be recover and reuse, safe disposal or energy recovery^[1]. Solvents are used widely in industries and it exists in consumer products that human exposes daily. It also can present to the environment when it releases from industries into drinking-water where animals can be effected on their livers, kidneys, and there is a carcinogen solvent for human and animals. Meanwhile, researchers hesitate to used green solvents instead of conventional solvents, despite their toxicity industries and laboratories are still uses hazard solvents that can whether the result in high yield or not. However, Green chemistry develops methods, the synthesis that reduces pollution and avoids derivatives for reaction. Also, green chemistry tries to use environmentally solvents that result in good solutions. Removal of volatile organic compound (VOC) is essential due to the emissions that damage environments. Here, three type of solvents effects environments in long-term use from whether industries or natural reactions.

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Figure 1: three type of solvents causes damage to environments, theses solvents effect on environment will be illustrated below.

Tetrachloroethylene is also known as (“PERC”) is non-flammable liquid use as a dry cleaning agent, and metal degreasing solvent also can be found in consumer products. However, Tetrachloroethylene can affect air, water, and soil, and it releases to air by dry cleaner industries or consumer products. Tetrachloroethylene broke down to the air and transported to a human body by inhalation which is considered to the carcinogen to humans or animals. Tetrachloroethylene has two pathways reaching to water by rain or snow which will be evaporated and contaminated in the air, or waste industrial facilities. Having Tetrachloroethene in water is the carcinogen to human, and the growth of soil will contain where there are claims that Tetrachloroethene is causing Birth defect for the human. These applications have been rejected by a study of Prenatal Exposure to Tetrachloroethylene in drinking water, where result in no effect on a birth defect^[2].

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Figure 2: the following compound is non-truadional material that promise to be replacement solvent.

D-limonene is naturally occurring monocyclic terpene that found in peel oils, evergreens, and human milk. It has low toxicity, and it recognizes as safe by the U.S Food and Drug Administration. It is efficient as a solvent in cleaning and degreasing application, which work on replacing toxic and anti-environment solvents to avoid waste and derivatives. Meanwhile, d-Limonene a negligible effect on human where the experiment has been doing by Hirotsune Igimi and his colleagues in 1974^[3]. Where d-limonene advantages are many in industries, adhesive removal, aerosol ingredient, marine vessel cleansing, etc. d-limonene soluble in water, and it is somewhat resistant to aerobic and anaerobic biodegradation in water and soil. The long-term effect is unknown on human also d-limonene is classified as non-carcinogen and nonmutagenic. However, it contains short-term effect on human skin and eyes. In the environment, d-limonene is readily biodegradable, not consider Sara title III compound, and not regulated by the Clean Air Act. This is why the replacement of Tetrachloroethylene (“PERC”) in industries uses.

Today, the emissions of the chemicals have been banned globally while scientists estimate that 39,000 metric/tons were released into the atmosphere every year. Carbon tetrachloride accounts for about 11precent of chloride that destroys stratospheric ozone^[4]. Carbon tetrachloride is one of the most popular solvents in the past, but due to the health damage that caused by carbon tetrachloride, the uses have been eliminated. Many studies have replaced carbon tetrachloride with tetrachloroethylene, even though tetrachloroethylene is a hazard to the environment. The replacement of the is due to carbon tetrachloride does not contain “H” and without C-H bonding is hard to undergo free-radical reactions. When carbon tetrachloride release to land is expected to be evaporated from soil to the groundwater, Volatilization from the ground to air is supposed to be a critical process. It is because of the existence of vapor pressure in the dry soil surface. Carbon tetrachloride has nearly estimated resident time in the atmosphere from 30 to 50 years^[5].

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Benzotrifluoride (C₆H₅CF₃) is less toxic than and more environmentally friendly alternative solvent to carbon tetrachloride, Chlorinated solvents, Chlorobenzene, ..etc. Where the replacement of Benzotrifluoride is due to the properties of Benzotrifluoride like Stable in strongly necessary conditions and Non-ozone depleter. However, Benzotrifluoride might have some cons in industries such prepared industrially from toluene, and Solvent removal requires more energy but is more beneficial to the environment. An example is taken from EPA (U.S Environmental Protection Agency) were stated that Benzotrifluoride is acceptable for usage but under the condition of a subject to a 100 ppm acceptable exposure limit (1999). No doubts that Benzotrifluoride is affecting humans, but about it beneficial in the environment it replaces. Based on an experiment of Benzotrifluoride in soil indicated that Benzotrifluoride would have low mobility in soil, volatilization of Benzotrifluoride maybe distinguished from the moist soil surface, and biodegrading for Benzotrifluoride will be vital fate process in soil according to biodegradation test^[6]. Where in atmospheric fate there is study show that Benzotrifluoride will exist in the ambient atmosphere, vapor-phase Benzotrifluoride is degreed in the atmosphere by reaction in photochemical radical that produce hydroxyl. The lifetime for this reaction is estimated to be 35 days; it is environmentally processing that doesn’t have a direct effect on the environment^[7].

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1,4-Dioxane is a colorless flammable solvent that used to formulate inks, coating, and adhesive where it is also used in petroleum industries and widely use with chlorinated solvents mainly 1,1,1 tricolor ethane (TCA). 1,4-Dioxane is used as a solvent stabilizer and is regulated as hazardous waste. 1,4-Dioxane is listed with pollutants solvents in air and water by National Pollutant Discharge Elimination System (NPDES), 1,4-Dioxane miscible with water, also mix with water quickly and can be found in ground-water plums far away than any other solvents, 1,4-Dioxane probably is the carcinogen to human based on the animal study. EPA claims that 1,4-Dioxane half-life time is 1-3 days in the atmosphere. 1,4-Dioxane short-term effects are vertigo, anorexia, headache, drowsiness, irritation to nose, eyes, and lungs. While the long-term impact is in drinking-water, In three epidemiological studies on workers expose to 1,4-Dioxane resulting in numbers of cancer cases, and EPA has classified 1,4-Dioxane as B2 probably carcinogen. Note that this information is taken from EPA^[8], Integrated Risk Information System (IRIS) which contain information about 1,4-Dioxane carcinogen and secondary source is Hazardous Substance Bank Data. In air, ambient levels of 1,4-dioxane is unavailable where the higher concentration of 1,4-Dioxane is found in water, based reports on 1988 to 1991 in Japan, that is the maximum concentration of 1,4-Dioxane exacerbated ranged from 1.1 to 109 μg/L in hazardous waste disposal sites, wherein 2000 to 2001, the focus of 1,4-Dioxane is from 0.16 to 0.15 μg/L. (Yasuhara et al. 1997)^[9]. So the concentration is eliminated due to the possible carcinogen in liver and kidney that can impact human and animals.

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The alternative solvents for 1,4-Dioxane are 2-Methyltetrahydrofuran (2-MeTHF) due to green properties that have and can fulfill the requirements to replace 1,4-Dioxane. 2-Methyltetrahydrofuran (2-MeTHF) is completely miscible with water and produce clean water phase spill without emulsion. Advantages of using 2-Methyltetrahydrofuran (2-MeTHF) as alternative solvents are more readily dried, very stable in the acidic environment, etc. Significant benefits of the replacement are that 2-Methyltetrahydrofuran (2-MeTHF) is following green principle in reducing risk and minimize environmental footprint. 2-MeTHF is mostly found in very useful solvents biphasic reactions, especially with aqueous NaOH. It is the suitable replacement for 1,4-Dioxane because it can take action in industries as the solvent with multi-application capability. Also, MeTHF drives from renewable raw sources which no environmental impact^[10]. A study by C. Stewart Slater and his colleagues consider 2-Methyltetrahydrofuran (2-MeTHF) green solvents since it manufactured from renewable raw materials, and work on the measure of greeness of 2-MeTHF by analysis. The analysis is preferred to be in 2-MeTHF production and industrial use. 2-MeTHF often is a substituted for chlorinated solvents in organometallic and biphasic reactions. The starting materials are 2-furfuraldehyde (furfural) is produced from corn cob waste by converting pentoses to acid hydrolysis. The evaluation of each step is to determine the overall life cycle and CO2 emission for each starting materials and immediate production. The division of total carbon is fired solvent made from renewable raws, profoundly reduce the overall footprint of carbon. This evaluation results in the reduction of carbon emissions by 97% when they were using 2-Methyltetrahydrofuran (2-MeTHF) as the solvent^[11].

To abbreviate, the concepts of alternative green solvent that can replace the hazardous solvents that cause diseases in many years whether to humans or animals, the replacement of Tetrachloroethylene is being studied for many years where all chlorinated solvents are lethal for environments based on OSHA publications. In a laboratory, the green solvents properties can be as efficient as the well-known solvents with regard that most of them can be reused. The reason for choosing two chlorinated solvents is because of its highly efficient for environments especially Carbon tetrachloride. Carbon tetrachloride is lethal to the environment and must be replaced by less hazardous solvents like benzotrifluoride. Dozens of studies admit that 1,4-Dioxane is the carcinogen in long-term exposure. Also, EPA has classified 1,4-Dioxane is the carcinogen. The alternative solvent for 1,4-Dioxane is 2-Methyltetrahydrofuran (2-MeTHF) due to the high specification and properties that can be alternative to 1,4-Dioxane. Also, the significant advantage of 2-ME THF is the follow of green principles. The consumer products that contain the Tetrachloroethylene are Furniture polish and cleaners, Aerosol paint concentrates, Paint and varnish removers, and Waterproofing compounds^[12]. Where the products included Carbon tetrachloride are Miscellaneous paint-related products, Other specialty cleaning and sanitation products, and Paint and varnish removers^[13]. 1,4-Dioxane can exist on hair relaxers, hormonal creams, anti-aging products, and baby soap^[14].

^[1] Lancaster, M. Green Chemistry An Introductory Text. 2002

^[2] Hayes, JR, LW Jr Condie, and JF Borzelleca. "The SubchronicToxicity of Tetrachloroethylene (perchloroethylene) Administered inthe Drinking Water of Rats." Pubmed 25 1.119 (1986). Print

^[3] Igimi, Hirotsune, et al. “The use ofd-Limonene preparation as adissolving agent of gallstones.” The American Journal of DigestiveDiseases, vol. 21, no. 11, 1976, pp. 926–939., doi:10.1007/bf01071903.

^[4] Beutel, Allard. NASA , 20 Aug. 2014. https://www.nasa.gov/press/2014/august/ozone-depleting-compound-persists-nasa-research-shows/

^[5] Philip H. Howard,. Handbook of Environmental Fate and ExposureData For Organic Chemicals. Vol. 2. New York: N.p., 1990. Print.

^[6] James J. Maul, Philip J. Ostrowski, Gregg A. Ublacker, BrunoLinclau, and Dennis P. Curran. "Benzotrifluoride and Derivatives: Useful Solvents for Organic Synthesis and Fluorous Synthesis." (1999). Print.

^[7] "Technical Fact Sheet – 1,4-Dioxane." EPA. United StateEnvironmental Protection Agency, Jan. 2014. Web. 5 Nov. 2017. <https://www.epa.gov/sites/production/files/2014-03/documents/ffrro_factsheet_contaminant_14-dioxane_january2014_final.pdf>

^[8] "Technical Fact Sheet – 1,4-Dioxane." EPA. United StateEnvironmental Protection Agency, Jan. 2014. Web. 5 Nov. 2017. <https://www.epa.gov/sites/production/files/2014-03/documents/ffrro_factsheet_contaminant_14-dioxane_january2014_final.pdf>

^[9] Yasuhara, A, Y Tanaka, A Tanabe, K Kawata, and T Katami. "Elution of 1,4-dioxane from Waste Landfill Sites." Elution of 1,4-dioxane from Waste Landfill Sites 71.3 (2003): 641-47. Print

^[10] ace, Vittorio, et al. “ChemInform Abstract: 2-Methyltetrahydrofuran (2-MeTHF): A Biomass-Derived Solvent withBroad Application in Organic Chemistry.” ChemInform, vol. 44, no. 5, 2013, doi:10.1002/chin.201305185.

^[11] Slater, C. Stewart, et al. “Environmental analysis of the life cycleemissions of 2-Methyl tetrahydrofuran solvent manufactured fromrenewable resources.” Journal of Environmental Science andHealth, Part A, vol. 51, no. 6, 2016, pp. 487–494., doi:10.1080/10934529.2015.1128719

^[12] n.d.Consumer products. TETRACHLOROETHYLENE -- Consumer Products. Retrieved November 5, 2017, fromhttp://scorecard.goodguide.com/chemical-profiles/consumer-products.tcl?edf_substance_id=127%2D18%2D4

^[13] n.d.Consumer products. CARBON TETRACHLORIDE -- Consumer Products. Retrieved November 5, 2017, fromhttp://scorecard.goodguide.com/chemical-profiles/consumer-products.tcl?edf_substance_id=56%2D23%2D5

^[14] n.d.Natural Consumer Products Found Contaminated withCancer-Causing 1,4-Dioxane in Groundbreaking Analysis Releasedby OCA. Natural Consumer Products Found Contaminated withCancer-Causing 1,4-Dioxane in Groundbreaking Analysis Releasedby OCA. Retrieved November 5, 2017, fromhttps://www.organicconsumers.org/news/natural-consumer-products-found-contaminated-cancer-causing-14-dioxane-groundbreaking-analysis