Treatment decolorization

Adsorption at the solution-carbon interface is already widely used on a large scale for water treatment, decolorizing, gold recovery, etc. (Derbyshire et al., 1995). In addition to these well-established applications, considerable interest is now being shown in the potential use of activated carbons for the removal of a wide range of pollutants such as aromatic hydrocarbons, humic acids and heavy metal ions (Costa et al., 1988 Youssef et al., 1996) and for the treatment of radioactive waste (Qadeer and Saleem, 1997). The aims of the applied research are generally to optimize the performance of the available commercial grades of activated carbon, to develop new products and to elucidate the mechanisms of adsorption (Blasinski et al., 1990). 

Sakoda, A., Nomura T. and Suzuki M. (1996), Application of Activated Carbon Membrane to Water Treatments Decolorization of Coke Furnace Wastewater, Adsorption, 3(1), 93-98. 

If lighter colors than these are desired it is necessary to decolorize all the melanin in the hair in a preliminary step, and then add color back to the desired depth in a second treatment. This is known as a double-process treatment. The decolorization step consists of treating the hair with an alkaline mixture of persulfate salts and peroxide. The persulfate is added to the peroxide as a dry powder immediately before applying to the hair. Although the persulfate salts alone do not have any bleaching effect, the persulfate—peroxide mixture can remove all the melanin in the hair. Dark brown or darker hair can be lightened to a light blonde shade in about an hour. 

Adsorbents. Acid activated clays have been widely used to treat mineral, vegetable, and animal oils. The primary objective of such treatment is decolorization and, at least in the case of edible oil, to remove components that contribute to off-tastes. Typically the oil is filtered through a granular clay product or treated with finely ground clay and subsequendy filtered. 

Diatomaceous earths may resemble the forms of the charcoals. The earths are primarily filter aids, precoats or adsorbents, the hmction of the filter medium being secondary. Fuller s earth and clays are used for decoloring applications diatomaceous earths are used for clarification. The adsorbtivity of diatomaceous earth works in the same fashion as activated carbon, but isotherms (affinity) for many chemical species like the hydrocarbons is weaker. For this reason, activated charcoal or carbon is much preferred in wastewater treatment applications expecially when taste and odor issues are priorities. 

The 2,3-dichlorophenoxyacetic acid and n-butyryl chloride are placed in the reaction vessel and stirred while the aluminum chloride is added portionwise over a 45-minute period. The mixture then is heated on the steam bath for 3 hours and allowed to cool to room temperature. The gummy product obtained is added to a mixture of 300 ml of crushed ice and 30 ml concentrated hydrochloric acid. The resulting mixture is extracted with ether and the extract evaporated at reduced pressure. The residue Is suspended in boiling water and dissolved by addition of a minimum quantity of 40% sodium hydroxide. After treatment with decolorizing charcoal and filtering, the hot filtrate is made acid to Congo red paper and chilled in ice. 

After 2 hours the mixture is cooled to about 0°C and the crude product Is collected by filtration, washed with diethyl ether and dried in a vacuum oven. After treatment with decolorizing charcoal and recrystallization from an equivolume mixture of isopropanol and methanol, the product, 2,5-bis(2,2,2-trifluoroethoxy)-N-(2-piperidylmethyl)benzamide hydrochloride has a MP of 228°C to 229°C. 

The fructose solution was decolorized by treatment with activated charcoal and concentrated under vacuum to a thick syrup. Two volumes of hot 95% ethyl alcohol were added, and the solution was heated to a boil and filtered to remove a small amount of insoluble material. After cooling, three volumes of ethyl ether were added, and the solution was allowed to stand overnight in the refrigerator. Fructose separated from the solution as a thick syrup and was... 

The mixture is then cooled and sodium bisulfite added to decolorize. Recrystallization of the product from methanol gives about 8 g, MP 147° to 150°C. The /3-(3-amino-2,4,6-triiodophenyl)-0 -ethylpropionic acid may be purified further by precipitation of the morpholine salt from ether solution and regeneration of the free amino acid by treatment of a methanol solution of the morpholine salt with sulfur dioxide. The pure amino acid has the MP 155° to 156.5°C. 

A solution of 5.0 g of a-ethyl-(3-(aminophenyl)propionic acid in 100 ml of water containing 5 ml of concentrated hydrochloric acid was added over a period of h hour to a stirred solution of 3.2 ml of Iodine monochioride in 25 ml of water and 25 ml of concentrated hydrochloric acid heated to 60°C. After addition was complete, the heating was continued for h hour longer at 60° to 70°C. A black oil separated which gradually solidified. The mixture was then cooled and sodium bisulfite was added to decolorize. Recrystallization of the product from methanol gave about 8 g of a-ethyl-(3-(2,4,6-triiodo-3-aminophenyl-pro-pionic acid, MP 147° to 150°C. The product could be further purified by precipitation of its morpholine salt from ether solution and regeneration of the free amino acid by treatment of a methanol solution of the morpholine salt with sulfur dioxide. The pure amino acid had the MP 155° to 156.5°C (corr). 

It is obtained by distn of high-boiling petroleum fractions, followed by purification. The latter operation consists of treatment with coned sulfuric acid, then coned Na hydroxide soln, and filtration thru decolorizing carbon. In order to reduce the solid paraffins, the oil is chilled aind filtered... 

Note The reagent can be just as successfully employed on silica gel, kieselguhr, aluminium oxide and polyamide layers as it can with RP and NH2 phases. The final treatment with ammonia vapor to decolorize the background can be omitted in the last case. 

For consistent, comparable results it is essential that a fresh sample blank be processed and otherwise be treated identically with each current batch of field samples. Whenever possible, this blank specimen should be from the same locality and should have the same previous spray (or other) history as the actual samples. Frequently, fruit and vegetable parts possess benzene-extractable pigments or other substances not removable by the decolorizing treatment utilized. In order to eliminate such background interfer-... 

There are several chemical compounds found in the waste waters of a wide variety of industries that must be removed because of the danger they represent to human health. Among the major classes of contaminants, several aromatic molecules, including phenols and aromatic amines, have been reported. Enzymatic treatment has been proposed by many researchers as an alternative to conventional methods. In this respect, PX has the ability to coprecipitate certain difficult-to-remove contaminants by inducing the formation of mixed polymers that behave similarly to the polymeric products of easily removable contaminants. Thus, several types of PX, including HRP C, LiP, and a number of other PXs from different sources, have been used for treatment of aqueous aromatic contaminants and decolorization of dyes. Thus, LiP was shown to mineralize a variety of recalcitrant aromatic compounds and to oxidize a number of polycyclic aromatic and phenolic compounds. Furthermore, MnP and a microbial PX from Coprinus macrorhizus have also been observed to catalyze the oxidation of several monoaromatic phenols and aromatic dyes (Hamid and Khalil-ur-Rehman 2009). 

Acid Orange 7 Sludge originally collected from a pulp and paper wastewater treatment plants Color removal of 96% was achieved in the presence of liposomes that facilitated uptake of dyes by anaerobic biomass, leading to a fast decolorization. Amines such as sulfanilic acid and aniline were mineralized by inocula with high microbiological diversity, even with domestic effluent. Orthanilic and metanilic acids and 1-amino-2-naphtol were persistent under tested conditions [176]... 

Reactive Red 3.1 Activated sludge obtained from domestic and industrial effluent treatment plants Decolorization rates of up to 30 mg L 1 h 1 were observed in case of activated sludge under anaerobic conditions. In anaerobic packed bed reactor [15]... 

Xu M, Guo J, Cen Y et al (2005) Shewanella decolorationis sp. nov., a dye-decolorizing bacterium isolated from activated sludge of a wastewater treatment plant. Int J Syst Evol Microbiol 55 363-368... 

Adedayo O, Javadpour S, Taylor C, Anderson WA, Moo-Young M (2004) Decolorization and detoxification of methyl red by aerobic bacteria from a wastewater treatment plant. World J Microbiol Biotechnol 20 545-550... 

Sandhya S, Swaminathan K, Swaminathan T (2007) Decolorization and treatment of recalcitrant dye industry wastewater containing azo dyes. In Trivedi PC (ed) Industrial pollution and its management. Aavishkar, India, pp 148-171... 

---