Waste treatment anilines

Releases of aniline in industrialized countries is considerable. According to the US Toxic Release Inventory, during 1998, eighty-two factories in the US released 1,449,754 lbs. of aniline, 217,223 to the atmosphere, 19,549 to surface waters, 1,161,911 by underground injection, 252 to land and 50,819 to disposal sites. While aniline waste is nowadays subjected to recovery, management, energy recovery and waste treatment, this was not so in the past, when anilines caused environmental injuries. The toxic impact of many dyes, e.g. in waste streams and releases to surface waters, arises from the fact that they are degraded, cleaved or reduced to aromatic amines. 

Distribution of aniline and aromatic amines depends on the level of waste treatment, which in turn determines the amount released to the environment. Aniline, unlike secondary and tertiary amines, is moderately soluble, and is released to the environment primarily in wastewater from its manufacture, and at sites where polyurethanes, rubber,... 

After leaving the reactor, the reaction mixture consisting of aniline, water, and excess hydrogen is cooled and condensed prior to the purification steps. First, the excess hydrogen is removed and recycled back to the reactor. The rest of the mixture is sent to the decanter where the water and aniline are separated. The cmde aniline, which contains less than 0.5% of unreacted nitrobenzene and about 5% water, is distilled in the cmde aniline column. The aniline is further dehydrated in the finishing column to yield the purified aniline. Meanwhile, the aqueous layer from the decanter, which contains about 3.5% aniline, is extracted to recover the aniline and clean up the water before it is sent to the waste-water treatment plant. 

Brillas E, Casado J (2002) Aniline degradation by electro-Fenton and peroxi-coagulation processes using a flow reactor for waste water treatment. Chemosphere 47(3) 241-248... 

The peroxidase reaction of heme peroxidases has found technical uses mainly for the polymerization of phenols and anilines (Scheme 2.13) [206-216] and for waste water treatment [217-220], whereas phenol coupling reactions in the biosynthesis of e.g. vancomycin are carried out by P450-type cytochromes [221],... 

Kirk DW, Sharifian H, Foulkes FR. Anodic oxidation of aniline for waste water treatment. J Appl Electrochem 1985 15 285-292. 

Aniline is the parent compound of the aromatic amines, which are used in the synthesis of agrochemicals, dyes, and pharmaceuticals. There is a concern that aromatic amines may be released into the environment during production processes or incomplete treatment of industrial waste streams. Additiondly, aromatic amines can enter the environment from the reduction of azo dyes, polynitroaromatic munitions (e.g. TNT), and dinitro herbicides, and from hydrolytic degradation of several classes of pesticides, including the phenylurea, phenylcarbamate, and acylanilide herbicides. 

Aiuline and a range of substituted anilines and other aromatic anilines eg diethylaniline, ethylbenzylaniline, ethyltolylaniline and antinonaphthalene were detected only in the extract from the industrial sludge. These compounds are commonly used intermediates in industrial synthesis and their presence reflects the catchment to this particular treatment works. In contrast, indole and a series of indoles (methylindole, methoxyindole) were detected only in the domestic sludge. Some of these compounds are constituents of human faeces and their presence is presumably due to the high proportion of domestic waste received by this treatment works. 

In addition to the investigation of numerous model compounds, real wastes from chemical, pharmaceutical and food industry, from municipal sewage treatment plants, and from military and nuclear power facilities were tested in bench and pilot scale plants [110]. For a better understanding of supercritical water oxidation, single components like 2,4-dinitrotoluene, acetic acid, ammonia, aniline, cyanide, dichloromethane, ethanol, formic add, hexachlorocydohexane, hydrogen, phenol, PVC, DDT, pyridine, thiophene, toluene, trichloroethylene, and 1,1,1-trichloroethane were studied. From these experiments, kinetic data were obtained. The destruction efficiency, which is the ratio between the residual total organic carbon content (TOC) and the initial TOC achieved for these compounds is up to 99.999 % [83]. Also flames in supercritical water, e.g. by oxidation of methane with oxygen, have been studied [111, 112]. 

Wastewaters from paper factories containing dyes particularly aniline and sulfur ones are generated from the paper treatment process consisting in the addition of fillers and dyes to the bleached cellulose material. As a result of multi-stage purification of wastewaters from the cellulose plants, there is obtained a low value of BOD (biochemical oxygen demand) - 4 mg/L but COD (chemical oxygen demand) is maintained on the level 75 mg/L. These waste-waters contain a small amormt of suspended matter - 5 mg/L, but they are characterized by intensive colour - 40 mg Pt/L [21]. 

The process of direct nitration of alkylated phenols was developed and implemented in the manufacturing plant. Later, the process was extended to nitration of phenol and several other alkylated phenols, substituted aniline compounds, and so on, by McDaniel and Gross. The process was implemented successfully to meet customer demand because of considerable reduction of in-process pollution streams, which could be treated in the plant treatment facihty with minimal plant modifications and ease of operation. The problems of treating and disposing of process wastes off-site were eliminated, making the process feasible compared to the DNBP process. 

EMBRs present an attractive option for the treatment of harsh industrial wastewater. As summarized in Table 20.8, successful treatment of various hydrophobic and volatile organic pollutants including phenol, benzene, toluene, xylene, aniline and several other chlorinated aniline derivatives, dichloroethane has been demonstrated in a few laboratory studies (Almeida et al, 1999 Brookes and Livingston, 1994 Livingston et al., 1998 Mehdizadeh et al., 2011). EMBRs are highly suited for the treatment of hazardous wastewater and toxic waste clean-up (Almeida et al, 1999 Brookes and Livingston, 1994 Livingston et al, 1998 Mehdizadeh et fl/.,2011). 

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