Adsorption/oxidation

Methanol, Formaldehyde, and Formic Acid Adsorption/Oxidation on a Carbon-Supported Pt Nanoparticle Fuel Cell Catalyst A Comparative Quantitative OEMS Study... 

Markovic NM, Schmidt TJ, Grgur BN, Gasteiger HA, Behm RJ, Ross PN. 1999. The effect of temperature on the surface process at the Pt(lll)-liquid interface Hydrogen adsorption, oxide formation and CO oxidation. J Phys Chem B 103 8568. 

Several methods are available to remove gasoline constituents from water, such as air stripping, biorestoration, activated carbon adsorption, reverse osmosis, ozonation, oxidation, resin adsorption, oxidation with hydrogen peroxide, ultraviolet irradiation, flotation, and land treatment. 

Bandosz TJ. On the adsorption/oxidation of hydrogen sulfide on unmodified activated carbons at ambient temperatures,/. Coll. Interface. 2002, 246,1-20. 

Impedance analyses of the Al under corrosion were conducted via EIS. On the basis of the models previously established for the corrosion of other metals in both aqueous and nonaqueous electrolytes,the corrosion process was proposed as a two-step adsorption/oxidation/desorption process (Scheme 19). ... 

On the basis of the EQCM observations, the authors proposed an adsorption/oxidation/desorption mechanism for the severe pitting corrosion of Al in Lilm- and LiTf-based electrolytes, which is schematically shown in Scheme 19 and Figure 27b.According to this mechanism, Al oxidizes to form adsorbed Al(Im)3 that eventually desorbs from the surface because these species are soluble in the electrolyte solvents. It is the desorption of these oxidized products that leaves the otherwise smooth Al surface with pits. The possibility also exists that, before desorption occurs, the adsorbed species undergoes further oxidation however, since the oxidation of Im is insignificant below 4.5 V according to studies carried out on nonactive electrodes similar to Al, oe seems unlikely that further oxidation of the adsorbed Al-(Im)3 would occur. 

Kinetic system, wherein the pathways along the system are moving toward some state of local equilibrium, which in tnm determines the rate of change along the pathway. In the context of a kinetic approach, which is relevant to geochemical processes, dissolntion-precipitation, exchange-adsorption, oxidation-reduction, vaporization, and formation of new phases, are discussed here. 

Haas Company (Philadelphia, PA), (2) reverse osmosis (RO), (3) adsorption/oxidation with PAC and copper, and (4) ultraviolet irradiation/ozonation (UV/O3). 

All these processes are very expensive for the purpose of removing a small amount of cyanide. The adsorption/oxidation process with PAC and copper could be easily incorporated into existing biological treatment systems however, the concern of copper toxicity in the final effluent makes this process undesirable. 

A large number of techniques have been described in the literature, for example, dyestulf adsorption, oxidative and reductive treatments, electrochemical oxidation or reduction methods, electrochemical treatment with flocculation, membrane separation processes, and biological methods [37-55]. Each of these techniques offers special advantages, but they can also be understood as a source of coupled problems, for example, consumption of chemicals, increased COD, AOX, increased chemical load in the wastewater, and formation of sludge that has to be disposed. 

Platinum electrodes are widely used as an inert electrode in redox reactions because the metal is most stable in aqueous and nonaqueous solutions in the absence of complexing agents, as well as because of its electrocatalytic activity. The inertness of the metal does not mean that no surface layers are formed. The true doublelayer (ideal polarized electrode) behavior is limited to ca. 200-300 mV potential interval depending on the crystal structure and the actual state of the metal surface, while at low and high potentials, hydrogen and oxygen adsorption (oxide formation) respectively, occur. 

Physical adsorption Oxidation by strong acids Glow-discharge plasma... 

Feasibility of Munitions Wastewater Treatment by Adsorptive Oxidations , Re-Entry Environ Syst Div, General Electric Co, Philadelphia (1976) CA 86,130071 (1976) (AD-A020744)... 

Kunzru, S. and Chaudhuri, M. (2005) Manganese amended activated alumina for adsorption/oxidation of arsenic. Journal of Environmental Engineering, 131(9), 1350-53. 

Figure 8.4 Cyclic voltammograms of one to five layers of bis-bipyridinum cyclophane (1) cross-linked AuNPs at an ITO electrode showing adsorption (oxidation) and desorption (reduction) of oxygen at the NP surface corresponding to surface area. 1.0 M H2S04, scan rate = 50 mV s 1. Inset Calibration curve is the number of AuNPs cm 2 (n) versus number of layers.4 (Reprinted with permission from A. N. Shipway et al., ChemPhysChem 2000,1, 18-52. Copyright Wiley-VCH Verlag GmbH Co. KGaA.)...

The treatment methods for remediation of energetic materials from soils are divided on in situ and ex situ biological (bioremediation, phytoremediation, composting), in situ and ex situ physico-chemical (adsorption, oxidation, electrokinetic separation, extraction, solidification, reduction, soil washing), in situ and ex situ thermal (pyrolysis, desorption) [1]. Among the above described... 

The objective of this paper is to demonstrate that unique surface heterogeneity of sludge derived materials is a factor governing t " performance as desulfurization adsorbents. Complex chemical nature of inorganic matrix provides active centers for adsorption/oxidation. On the other hand, carbonaceous matter, is responsible for existence of pores of small diameters where oxidation process occurs and where catalysts can be highly dispersed. All of these provide active centers and space for storage of the surface oxidation products. 

Another interesting observation is almost identical behavior of samples exposed for SOj adsorption. Regardless the carbonization temperature the same amounts of SO, are adsorbed on the samples exhausted in the HjS breakthrough test. This suggests that after exhaustion of all active centers responsible for HjS adsorption the differences in surface chemistry, which play a role in sulfur dioxide adsorption/oxidation on fresh surfaces, seem to be somehow screened by HjS adsorption products. Nevertheless, it is interesting that still some capacity exists. 

An objective of this paper it to describe the results of our further investigation of the competition for adsorption sites between water and dimethyl disulfide molecules during methyl mercaptan adsorption on activated carbons. Moreover, we attempt to indicate the apparent borderlines between the conditions of adsorption processes leading to different adsorption/oxidation paths. Those working conditions have a significant effect on the feasibility of methyl mercaptan removal. 

A simple mechanism of adsorption/oxidation of hydrogen sulfide was first proposed by Hedden and coworkers [31]. According to them, dissociation of hydrogen sulfide occurs in the film of adsorbed water at the virgin carbon surface and then hydrogen sulfide ions, HS , are oxidized by oxygen radicals to elemental sulfur. Since then many studies have been done to account for such factors as a role of water [26, 32, 34, 36, 37, 40, 48, 49], role of oxygen [18—27], autocatalysis by sulfur [27, 28], influence of pore sizes [19, 29, 33, 35, 38], role of carbon surface chemistry [41—44], the effects of ash [49, 58—60], and last but not least, speciation of surface oxidation products [41—46]. 

A role of oxygen in the kinetic of the H2S adsorption/oxidation were studied by ToUefson and coworkers [18-27], Steijns and Mars [29], and Meeyoo... 

Figure 21.2 pH-dependent mechanism of H2S adsorption-oxidation (as described by Adib et al. [43]). 

Adsorption—oxidation of SO2 in oxygen atmosphere and in the presence of water occurs as follows [76] ... 

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