Absorption in alkaline solution

This reaction serves as a known model reaction to characterize mass transfer efficiency in micro reactors [7]. As it is a very fast reaction, mass transfer can be analysed solely The analysis can be done simply by monitoring color changes from pH indicators. Ammonia absorption in aqueous acidic solutions generally is even faster than carbon dioxide absorption in alkaline solutions. 

Roberts, D. and Danckwerts, P. V. Chem. Eng. Sci. 17 (1962) 961. Kinetics of CO2 absorption in alkaline solutions. I. Transient absorption rates and catalysis by arsenite. 

Table A gives the wavelengths of maximum absorption, together with the wavelengths of any subsidiary peaks in the range 230 to 360 nm, for the compounds in acid solution. Table B gives the wavelengths of maximum absorption in alkaline solution when values in acid solution are not recorded in the monographs in Part 2 or when the...

Oxidation of 32 with H2O2 in NaOH gives 3-isopentylanthranilic acid, which determines isopentyl group at position 7 of the indole ring. The presence of NH-CO bands (3400, 1540, and 1510 cm" ) in the IR spectrum of 32 is supported by the shift of UV absorption in alkaline solution. These bands disappear in the IR spectrum of acetyl or methyl derivatives, in which -N=C-OAc or -N=C-0CH3 groups have been produced. In parallel, in the methyl ether of 30... 

Danckwerts PV, Kennedy AM, Roberts D. (1963) Kinetics of CO absorption in alkaline solutions—II absorption in a packed column and tests of surface renewal models. Chem. Eng. Sci., 18 63-72. 

Another example is absorbing SO2 from the flue gases by absorption in alkaline solutions. In the hydrogenation of edible oils in the food industry, hydrogen gas is bubbled into oil and absorbed. The hydrogen in solution then reacts with the oil in the presence of a catalyst. The reverse of absorption is called stripping or desorption, and the same theories and basic principles hold. An example is the steam stripping of nonvolatile... 

Also called nitric oxide, nitrogen monoxide or oxidonitrogen, NO is a colorless, relatively unreactive radical that is essentially insoluble in aqueous solution. Simple absorption in alkaline solutions is not effective, since it is only physically absorbed [3,4,6]. Absorption in nitric acid decreases with acid concentration [4], and oxidation with ozone to produce acidic NO2 facilitates its absorption in alkaline media [6]. Absorption of NO with simultaneous oxidation at a gas diffusion electrode in alkaline solution eliminates the need for an oxidizing agent [6] ... 

In reality, the selectivity achieved in mixed H2S-CO2 absorption in alkaline solutions is higher due to the kinetics of the mixed gas absorption process as long as the mass-transfer coefficient of the absorber is high (Danckwerts, 1970). Thus, thermodynamics (or equilibrium behavior) alone is insufficient See Section 5.3.1.1. 

Absorption in alkaline solution is a common principle used in acid gases capture processes operating for decades in natural gas treatment. The reference absorbent is aqueous solution of monoethanolamine (MEA). The mechanism of capture is a combination of chemical and physical dissolution. The chemical dissolution is based on an acido-basic reaction. The reaction must be reversible in order to regenerate the absorbent solution and recover carbon dioxide for storage. The physical dissolution, usually observed fot high partial pressure of CO2, can be improved by addition of specific physical solvent. 

In analogy to the situation for bipyridine, the blue tris(l,10-phenanthroline)iron(3+) ion [1347949-7], [Fe(phen)2], must be obtained by oxidation of the corresponding iron(II) ion. [Fe(phen)2] has an absorption maximum at 590 nm, an absorptivity of 600 (Mem), and a formation constant of 10 . In solutions of pH > 4, this species is reduced to the iron(II) complex. The reduction is instantaneous in alkaline solution. At pH < 2, protons compete with iron(III) for the phenanthroline nitrogens and coordination is incomplete. [Fe(phen)2] is used most often in solution as an oxidant, but the trichloride [40273-22-1] and the triperchlorate monohydrate [20774-81-6] salts have been prepared. 

Photochemical decomposition of riboflavin in neutral or acid solution gives lumichrome (3), 7,8-dimethyl all oxazine, which was synthesized and characterized by Karrer and his co-workers in 1934 (11). In alkaline solution, the irradiation product is lumiflavin (4), 7,8,10-trimethyhsoalloxazine its uv—vis absorption spectmm resembles that of riboflavin. It was prepared and characterized in 1933 (5). Another photodecomposition product of riboflavin is 7,8-dimethy1-10-foTmylmethy1isoa11oxazine (12). 

Br20 a dark-brown solid moderately stable at —60° (mp —17.5° with decomposition), prepared by reaction of Bt2 vapour on HgO (cf. CI2O p. 846) or better, by low-temperature vacuum decomposition of BrOa. The molecule has C2v symmetry in both the solid and vapour phase with Br-O 185 1pm and angle BrOBr 112 2° as determined by EXAFS (extended X-ray absorption fine structure). It oxidizes I2 to I2O5, benzene to 1,4-quinone, and yields OBr in alkaline solution. 

That the ind-N atom in the anhydro-bases is the basic center is also obvious from a consideration of the ultraviolet absorption spectra of the anhydro-bases. In aqueous 0.1 A hydrochloric acid as well as in neutral alcoholic solutions each carboline anhydro-base gives rise to an ultraviolet absorption spectrum identical with that of the parent carbolinium salt. In alkaline solutions (pH above 11.5 in the case of the... 

The ultraviolet absorption spectra of the anhydro-bases in acid solution or in protic solvents are those of the 3,4-dihydro-)3-carbolinium ion (Ajnax 355 mp, for 438b and 438c). In alkaline solution and in nonionizing solvents absorption at a shorter wavelength (A ax 315 m/x) is observed. In general, solutions of the anhydro-bases in acid and in protic solvents are more deeply colored than their solutions in basic or in non-ionizing media. 

The third structural possibility, the formulation of the compounds as pseudo-bases (445) was eliminated in the case of the anhydro-bases derived from p /r-iV -alkyl-l-methyl-3,4-dihydro-j8-carbolinium salts on the basis of their ultraviolet absorption spectra. A structure such as 445 demands indole-type absorption (A jax 280 mp) which was not encountered in the spectra of the anhydro-bases under discussion. This is in accord with general experience. Pseudo-bases are generally found only when dehydration to anhydro-bases is structurally impossible Indole-type absorption was indeed found in the case of the product obtained by treatment of 3,4-dihydro-)3-carboline methiodide (452 R = H) with alkali.In acid solution this compound gave the expected absorption (A jax 355 mp). In alkaline solution, however, an indole-type absorption (A jax 285 mp) was observed. On this basis formulation of the product as a derivative of 2-formylindole (454) ( max 315 mp) was rejected. Although the indole-type absorption is in accord with the pseudo-base structure 453 (R = H), the elemental analysis and molecular weight were not compatible with this formulation and the product was regarded as a dimeric anhydro-base (455). 

Hydroxy-8-hydroxyethyl-6,7-dimethyl-2-pteridinone has been shown to have the same absorption spectrum in alkaline solution as its 1,7-dihydro derivative, namely peaks at 231, 283, and 316 mp. This... 

A method suitable for quantification of the functional class of bis(ethanol)amine antistatics, which lack UV chromophores, consists of reaction with methyl orange [53]. Atmer 163 (alkyl-diethanol amine) has been determined as a yellow complex at 415 nm after interaction with a bromophenol/cresole mixture [64]. Hilton [65] coupled extracted phenolic antioxidants with diazotised p-nitroaniline in strongly acidic medium and carried out identification on the basis of the visible absorption spectrum in alkaline solution. The antioxidant Nonox Cl in... 

Potter and co-workers 301) determined reducing sugars in plant materials by reducing copper(II) in alkaline solution to insoluble cuprous oxide and then measuring the excess copper in the filtrate. Mitschell248) conducted further studies on this method. Christian and Feldman 19) have described general procedures for the indirect determination of glucose and of protein. It is anticipated that in the future, we will see many more applications of atomic absorption spectroscopy to the indirect determination of nonmetals. 

The solutions usually cannot be cleaned up by extraction techniques because hydralazine decomposes in alkaline solution. However, there are many reactions that give rise to near ultraviolet or visible absorption bands suitable for quantitation. 

Jafarian et al. [130] have studied adsorption and absorption of hydrogen species on Ag electrodes in alkaline solution. Gurten etal. [131] have investigated the effect of alcohols MeOH, EtOH, and PrOH on hydrogen evolution reaction on Ag electrode in contact with 0.01 M NaCl solution. It was observed that the presence of alcohols increased the hydrogen yield and decreased anodic overpotential (for the Pt anode). 

HgS films have also been deposited from more conventional deposition solutions using thiourea and the tetraiodide complex of mercury—a strong complex—in alkaline solution. Both these and the previous films showed an optical absorption with a gradual absorption onset at 700 nm and a sharp one at 400 nm. 

Solutions are somewhat less dangerous but this fact can lead to careless handling due to a false sense of security. Precautions against internal consumption are obvious, but even more insidious is the potential danger of skin absorption. Many drugs are amine hydrochlorides In alkaline solution, the free base has increased lipophillic character, so the rate of skin absorption is increased. 

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