Removal of volatile organic compounds VOCs

Gold catalysts have nevertheless been used for the oxidation of various saturated and unsaturated hydrocarbons 71-74 AU/C03O4 exhibits the 

Complete oxidation of propene by Pt/A Os in the presence of carbon monoxide is made easier by admixture with Au/TiC 2, which oxidises the carbon monoxide and prevents its toxic effect on the platinum.77 

Oxygenated VOCs include methanol, ethanol, 2-propanol and acetone, and in general the comparative ease of destruction is  

About 1% Au/a-Fe203 is active for the combustion of methanol and its decomposition products (methanoic acid and methanal) at temperatures below 373 K, at a space velocity of 2000 h-1. Comparison of T50 values for Au/Fe2C 3 and conventional combustion catalysts Pd/Al2C 3 and Pt/A Os gave the order of activity 87 

503 and 353 K.91 Ethanol was successfully oxidised on Pd-Au/Al203 at 573 K, the presence of the gold stabilising the palladium against oxidation.92 

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The removal of volatile organic compounds (VOC) from air is most often accompHshed by TSA. Air streams needing treatment can be found in most chemical and manufacturing plants, especially those using solvents. At concentrations from 500 to 15,000 ppm, recovery of the VOC from steam used to regenerate activated carbon adsorbent thermally is economically justified. Concentrations above 15,000 ppm ate typically in the explosive range and... 

Wang et al. [42,67,68] have developed innovative biological process and sequencing batch reactors (SBR) specifically for removal of volatile organic compounds (VOCs) and surfactants. Related analytical procedures [57-64,71-91] available for process monitoring and control are available in the literature. 

Bio-Electrics, Incorporated, has developed the Electrofrac Detoxification System to treat hazardous contaminants in soil. The system, which was developed from gasification research, uses electrodes placed in soil to heat the site. There are potential applications of this technology for removal of volatile organic compounds (VOCs), pyrolysis of non-VOCs, treatment of organic residues, and in situ vitrification of soils and asbestos. There have been bench-scale tests of the technology for remediation applications. 

Croy Dewatering Environmental Services, Inc. (Croy), has developed the dual-phase recovery unit for the extraction of groundwater and the removal of volatile organic compounds (VOCs)... 

The Turbostripper is an air stripper technology for removal of volatile organic compounds (VOCs) from groundwater or wastewater. According to the vendor, it is a 100% nonclogging unit, based on its use of the patented Turbolill chemically resistant plastic ellipsoids. 

EnviroSep, Inc. (EnviroSep), has developed a thick-film absorption technology for the removal of volatile organic compounds (VOCs) from water. The technology uses a proprietary form of silicone rubber to absorb contaminants. The vendor claims the technology is effective for VOCs with less than 2% solubility in water and a boiling point of less than 200°C for the pure compound and is most efficient for use at sites with contaminant concentrations between 10 parts per million (ppm) and 2000 ppm. The technology is intended for aqueous waste streams. 

E-Z Stacker and E-Z Tray are commercially available modular air strippers for the ex situ removal of volatile organic compounds (VOCs) from groundwater. E-Z Stacker consists of 4 or 6 stacking units E-Z Tray units are arranged in pull-out drawers. The multiple sieve tray design of the E-Z Stacker uses forced-draft air bubble generation to provide VOC removal. All information is from the vendor and has not been independently verified. 

The cross-flow pervaporation system is an ex situ technology for the removal of volatile organic compounds (VOCs) from contaminated aqueous waste streams. Permeable hollow-fiber membranes preferentially adsorb VOCs. A vacuum on the other side of the membrane puUs the compounds through the membrane and partitions the VOCs from the aqueous stream. The organics may be recovered for reuse. 

In addition to zeolites, the MMS have been also applied in gas cleaning. In this regard, attention paid to this novel family of adsorbents is mostly because of the unique mesopore structure, which is not shared by any other families of adsorbents. On the other hand, the hydrophobic surface nature of the MMS [2] indicates that these materials are selective adsorbents for the removal of volatile organic compounds (VOCs) and other organic compounds contained in high-humidity gas streams or wastewater [119],... 

A. Removal of Volatile Organic Compounds (VOCs) from Air 10... 

Examples of environmental catalytic issues are selective catalytie reduction (SCR) of NO, removal of volatile organic compounds (VOC) decomposition of NO oxidation of CO from exhaust gas. SCR is now in a mature state. Several reviews have been published recently. 

Catalytic combustion applications can be classified as either primary or secondary pollution control, that is, emissions prevention or emissions clean-up. The most common example of catalytic combustion for emissions clean-up is the catalytic converter in the exhaust system of automobiles. Catalytic combustion is also increasingly used for the removal of volatile organic compounds (VOCs) from industrial exhaust streams. The use of catalytic combustion in exhaust gas clean-up is discussed in other sections of this Handbook this section deals only with primary control applications. 

In the present study a novel knitted silica-fiber was developed and enployed as a catalyst carrier. Different silica-fiber supported catalysts were prepared and studied for their performance in removal of volatile organic compounds (VOC) emissions, gas-phase hydrogenation of o-xylene, liquid-phase hydrogenation of citral and liquid-phase enantioselective hydrogenation of 1-phenyl-1,2-propanedione. 

The dense polyvinyl alcohol layer is supported by a porous PAN substrate membrane. Polyelectrolyte material [24] and chitosan [25], a natural product, are also potentially useful for dehydration by pervaporation. Sihcone rubber membranes developed for the removal of organic vapors from air can also be used for the removal of volatile organic compounds (VOCs) from water by pervaporation [23]. Because of the high hydrophobic nature of silicone rubber, VOCs are preferentially sorbed and transported through the membrane. 

Urtiaga et al. (2001) studied the parallelism and the differences in PV and vacuum membrane distillation (VMD) in the removal of volatile organic compounds (VOCs) from aqueous streams. In their study, two gas-liquid separation processes, PV and VMD, were compared in the application to the separation of chloroform-water mixtures. Both technologies include the transfer of separated compounds initially in liquid phase through a membrane to a low-pressure gas phase. The use of a solid membrane enhances the separation efficiencies. However, PV and VMD are based on different mechanisms and employ membranes of different characteristics. Selective membranes need to be used in PV processes, while the VMD process requires the use of microporous nonselective membranes. 

CNF AND ACNF FOR REMOVAL OF VOLATILE ORGANIC COMPOUNDS (VOCS)... 

Despite the low number of existing works on PVPRs, the investigations tend to cover the two main common applications of organophihc pervaporation i.e. the recovery of aroma compounds from process streams (Karlsson and Tragfirdh, 1993 Pereira et al, 2006 Trifunovic et a/., 2006) and the removal of volatile organic compounds (VOC) from aqueous effluents (Konieczny et al, 2008 Lipnizki and Field, 2002 Peng et al, 2003 Urkiaga et al, 2002). 

Removal of volatile organic compounds (VOCs) from aqueous solutions by pervaporation... 

Another possible application of the flue gas treatment technology is for the removal of volatile organic compounds (VOCs) and polycyclic aromatic hydrocarbons (PAHs), e.g., in flue gas treatment facilities of municipal waste incinerator plants. 

The removal of volatile organic compounds (VOCs) with ACs is of interest because these compounds can be very harmful for both human health and the environment, even at very low concentrations [6,107-109, 131-138],... 

A common example of vapor stripping involves removal of volatile organic compounds (VOCs) from water either obtained within a chemical process plant or discharged from it. Such a system rarely displays ideal solution behavior. The selectivity ai2 then becomes... 

The adsorbent wheel shown schematically in Figure 5.11 is used particularly for the removal of volatile organic compounds (VOCs) from vent streams. Whether the removed VOCs can be recovered depends upon the magnitude of the increase in concentration from the adsorption step to the desorption step. Solvent-laden air passes via a duct through one side of the wheel which rotates slowly. On the desorption side a lower fiowrate of heated air is used to desorb the VOCs. The two gas ducts do not have to be of the same size but it is obvious that the time for desorption must be less than or equal to the time for adsorption. 

Gas separations currently comprise a membrane market of two hundred million euros per year. Most of this business involves a variety of applications, such as separation of H2 from gases like N2, CH4, and CO separation of CO2 or O2 from N2 H2 recovery in oil refinery processes CH4 separation from biogas removal of water vapor CO2 and H2S from natural gas (NG) and removal of volatile organic compounds (VOCs) from air of exhaust streams. A much larger potential market lies in the separation of condensable gases, such as C3+ from H2 or CH4, and CsHg from CsHg. 

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