Phenol removal, from wastewaters

Acid or base can be used as an internal phase or stripping phase for ELM process depending upon solute to be extracted, for example, Cahn and Li [3] used NaOH solution as the internal phase for phenol removal from wastewater. H2SO4 solution was used as the internal phase for removal of ammonia [4-8]. The solute extraction rate also increases with an increase in the amount of internal reagent present in the emulsion. 

Phenol removal from wastewater was first commercialized around 1986 at the Nachung Plastic Factory in Guangzhou, China. In this, phenol can be removed from about 1000 ppm to 0.5 ppm with an extraction efficiency of greater than 99.95%. The internal reagent NaOH converts the phenol to sodium phenolate and the phenolate is trapped into the internal phase. 

HoUow-fiber SLMs have been used in the removal of phenol from aqueous matrices. Kujawski et al. [142, 143] studied polypropylene membranes impregnated with methyl-terbutyl ether, cumene, and/or a mixture of hydrocarbons. With Cyanex 923 (a mixture of trialkylphosphine oxides), the recoveries of phenol reached of 98% into the stripping phase from the 0.2 mol.dm solution of caustic soda [144, 145]. Carriers for phenol removal from wastewaters have included hnear monoalkyl cyclohexane [146], N,N-di(l-methyl heptyl) acetamide [147], dibenzo-18-crown-6 [148], dodecane [149], trioctylamine [150], and N-octanoylpyr-rolidine [151]. Many diluents and carriers are of synthetic origin, and so their application carries with issues of flammabUity, volatility, toxicity, and potential detrimental effects to the environment and the health of the human population [152]. 

Kujawski, W., Warzawski, A., Ratajczak, W., Porebski, T., Capala, W., Ostrowska, I. (2004). Application of pervaporation and adsorption to the phenol removal from wastewater. Separation and Purijication Technology 40 123-132. 

Table IL ELM System for Phenol Removal from Wastewater (5)...

Phenol and its compounds are ubiquitous water pollutants that are present in the effluents of a variety of chemical industries such as coal refineries, phenol manufacturing, pharmaceuticals, and industries of resin, paint, dyeing, textile, leather, petrochemical, pulp mill, etc. [9]. Phenols are known to be toxic and also, some of them, hazardous carcinogenic that can accumulate in the food chain. Phenolic compounds are a public health risk and they are heavily regulated in many countries, and must be removed from wastewater before they are discharged into the environment [10], For example, a 10 days consumption of polluted water with low concentrations (3 ppm) of 2,4-dichlorophenol can cause vomiting, paralysis, and even death in children [11, 12]. Phenol, 2-chlorophenol, and 2,4-dichlorophenol are ranked within the 250 most hazardous pollutants [13]. In addition, chlorophenols are commonly found in chlorinated water, since phenol can react with chlorine [14],... 

Resin adsorption. The resin adsorption is a good option for the selective removal of waste. This technique is normally used for the removal of ther-molabile organic solutes from aqueous waste streams. The solute concentration of solution ranges fiwm 1 to 8 percent. Moreover, synthetic cationic and anionic resins may be used to remove a hydrophobic, hydrophihc, or neutral solute, which can also be recovered by chemical methods. These resins are also used with a high concentration of dissolved inorganic salts in the waste stream. Their appUcations include phenol, fat, organics, and color removal from wastewater. They can be apphed for the removal of pesticides, carcinogens, and chlorofluoro compounds. 

Liquid extraction is utilized by a wide variety of industries. Applications include the recovery of aromatics, decaffeination of coffee, recovery of homogeneous catalysts, manufacture of penicillin, recovery of uranium and plutonium, lubricating oil extraction, phenol removal from aqueous wastewater, and extraction of acids from aqueous streams. New applications or refinements of solvent extraction processes continue to be developed. 

Transport of solutes through the LM occurs by either passive transport or by carrier-facilitated transport. Phenol, for example, is soluble in both phases, and treatment of an aqueous phenol solution with an emulsion results in a lowering of the external concentration of phenol as it passively diffuses through the hydrocarbon (HC) layer and into the internal aqueous phase. Equilibrium is reached when the concentrations of phenol in both aqueous solutions are equal (assuming no other conditions are present which would alter the distribution between the aqueous and HC phases). One way to alter this equilibrium is to trap phenol inside with a sodium hydroxide solution. Phenol ionizes at high pH, and the phenolate ion cannot permeate a HC layer trace amounts of phenol have been completely removed from wastewaters by this system (10, 11). This exclusion of charged molecules by the aliphatic hydrocarbon LM layer is desirable in some applications, but to employ LM enzyme reactors and/or separation systems with amino acids, it is necessary to incorporate carriers into the HC phase. 

Removal of phenol from wastewaters has been studied using non-Newtonian ELMs and the Taylor-vortex column. It was found that a decrease in the surfactant concentration in the ELM leads to a lower surfactant accumulation per unit interfacial area at the feed phase/ELM interface. As a result, the higher was the efficiency of phenol removal from the wastewater [97, 98]. An increase in the volume of the stripping phase in the ELM could result in a reduction of the LM thickness [74]. 

B11 Synergetic removal of aqueous Phenol removal from Activated carbon adsorbent and Wastewater treatment [21]... 

B13 Aqueous phenol decomposition Phenol removal from industrial n02 on silica beads, Ni or Co on Wastewater treatment [27]... 

Chitosan has been widely accepted in the purification process of water by virtue of its metal ion chelating capability and acting as a flocculating agent because of its poly-cationic character. It is also used as an adsorbent for removal of dyes from water. Pesticides and chemicals such as phenols, methyl mercury acetate, plutonium, etc., can be removed from wastewater [170]. 

Commercial Applications. Commercial applications include zinc removal from wastewater in the viscose fiber industry, phenol removal fi om wastewater, cyanide removal fi om waste liquors in gold processing, and in well control fluid. 

Phenols, widely used in industry, represent one of the most common organic water pollutants, being extremely toxic even at low concentrations. It is worth mentioning that phenol is relevant in environmental research, because it has been chosen frequently as a model pollutant and many data are available on its removal from wastewater treatments.Besides being toxic, phenol is also a refractory compound, its removal from wastewater being difficult. ... 

The Phenox process (254) removes phenol (qv) from the efduent from catalytic cracking in the petroleum industry. Extraction of phenols from ammoniacal coke-oven Hquor may show a small profit. Acetic acid can be recovered by extraction from dilute waste streams (255). Oils are recovered by extraction from oily wastewater from petroleum and petrochemical operations. Solvent extraction is employed commercially for the removal of valuable... 

Phenol can be oxidi2ed and hence removed, ie, to levels <20 / g/L, from wastewater (248). Moreover, addition of potassium permanganate to the return activated sludge results in reduction of odors issued from the aeration tanks of conventional activated sludge wastewater treatment plants without any change occurring to the microbiology of the system (249). 

The following are some of the typical industrial applications for liquid-phase carbon adsorption. Generally liquid-phase carbon adsorbents are used to decolorize or purify liquids, solutions, and liquefiable materials such as waxes. Specific industrial applications include the decolorization of sugar syrups the removal of sulfurous, phenolic, and hydrocarbon contaminants from wastewater the purification of various aqueous solutions of acids, alkalies, amines, glycols, salts, gelatin, vinegar, fruit juices, pectin, glycerol, and alcoholic spirits dechlorination the removal of... 

A A multistage extraction column uses gas oil for the preliminary removal of phenol from wastewater. The flowrate of wastewater is 2.0 kg/s and its inlet mass fraction of phenol is 0.0358. The mass fraction of phenol in the wastewater exiting the column is 0.0168. Five kg/s of gas oil are used for extraction. The inlet mass fraction of phenol in gas oil is 0.0074. The equilibrium relation for the transfer of phenol from wastewater to gas oil is given by... 

One common application of liquid-liquid extraction is the removal and recovery of phenol and compounds of phenol from wastewaters. Although phenol can be removed by biological treatment, only limited levels can be treated biologically. Variations in phenol concentration are also a problem with biological treatment, since the biological processes take time to adjust to the variations. 

Akaya G, Erhan E, Keskinler B, Algur OF (2002) Removal of phenol from wastewater using membrane-immobilized enzymes Part II. Cross-flow filtration. J Membr Sci 206 61-68... 

Oxidizing agents have been shown to be extremely effective for removing many complex organics from wastewater, including phenols, cyanide, selected pesticides such as ureas and uracils, COD, and organo-metallic complexes [11]. Many oxidants can be used in wastewater treatment. Table 9 shows the oxidation potentials for common oxidants [24]. The most widely used oxidants in the... 

Solaqua is a patented, ex situ process for the removal of organic contaminants from wastewater or groundwater. The technology uses ferric oxalate and hydrogen peroxide in the presence of light to produce hydroxyl radicals, which destroy organic contaminants such as aromatic hydrocarbons, phenols, alkanes, aUcynes, ethers, and ketones. Solaqua is not yet commercially available. 

Extraction is a process for separating components in solution by their distribution between two immiscible phases. Such a process can also be called liquid extraction or solvent extraction. The former term may be confusing because it also applies to extraction by solid solvents. Since extraction involves the transfer of mass from one phase into a second immiscible phase, the process can be carried out in many ways. The simplest example involves the transfer of one component from a binary mixture into a second immiscible phase — extraction of an impurity from wastewater into an organic phase. In some cases, a chemical reaction can be used to enhance the transfer, e.g., the use of an aqueous caustic solution to remove phenolics from a hydrocarbon stream. 

The INET contactors have also been applied to non-nuclear processes, such as the removal of a specific rare metal (yttrium) from other rare metals (Zhou et al., 2007), hydrocortisone from fermentation liquor (Zhou et al., 2006b), phenol from wastewater (Xu et al., 2006), and caffeine from coffee beans (Duan et al., 2006). As described by Zhou et al. (2007), the contactor rotor is driven by a motor that is not above the contactor. Instead, a belt connects the motor to the top of the rotor shaft. This design is possible because these materials are not radioactive, and hands-on maintenance is thus possible. 

Removal of sulfanilic acid from wastewater Lactic acid purification and concentration Enrichment of bisphenol A Phenol recovery from aqueous solutions Zinc(ll) recovery from HCI solution Hydrogen separation from methane steam conversion products... 

Nanoti, A., Ganguly S.K., Goswami, A.N. and Rawat, B.S. (1997) Removal of phenols from wastewater using liquid membranes in a microporous hollow fiber-membrane extractor. Industrial e[ Engineering Chemistry Research, 36, 4369. 

Although several peroxidase enzymes obtained from plant, animal, and microbial sources have been investigated for their ability to catalyze the removal of aromatic compounds from wastewaters, the majority of studies have focused on using HRP. In particular, it has been shown HRP can transform phenol, chlorophenols, methoxyphenols, methylphenols, amino-phenols, resorcinols, and various binuclear phenols [7], HRP was also used for the treatment of contaminants including anilines, hydroxyquinoline, and arylamine carcinogens such as benzidines and naphthylamines [7,8]. In addition, it has been shown that HRP has the ability to induce the formation of mixed polymers resulting in the removal of some compounds that are either poorly acted upon or not directly acted upon by peroxidase [7], This phenomenon, termed coprecipitation or copolymerization, has important practical implications for wastewaters that usually contain many different pollutants. This principle was demonstrated when it was observed that polychlorinated biphenyls (PCBs) could be removed from solution through coprecipitation with phenols [20]. However, this particular application of HRP does not appear to have been pursued in any subsequent research. 

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