Phthalic acid adsorption

The aquifer mineral constituents adsorbed most waste organic compounds, with the exception of formaldehyde. Adsorption of all organic acids except phthalic acid increased with a decrease in waste pH. 

Mono esters of dicarboxylic acids.1 Aliphatic straight-chain dicarboxylic acids when adsorbed on alumina react with diazomethane to form monomethyl esters in quantitative yield. Terephthalic acid, isophthalic acid, and 1,4-cyclohexanedi-carboxylic acid are also converted selectively to the monomethyl esters. However, phthalic acid does not show any enhanced selectivity under these conditions. Evidently selectivity for monoesterification results from adsorption of one of the acid groups on alumina. 

Sullivan KF, Atlas EL, Giam CS. 1982. Adsorption of phthalic acid esters from seawater. Environ Sci Technol 16 428-432. 

Sullivan, K.F., Atlas, E.L., Giam, C.S. (1982) Adsorption of phthalic acid esters from sea water. Environ. Sci. Technol. 16, 428 32. Swamy, P.A., Van Winkle, M. (1965) Vapor-liquid equilibria at 760 mm. of mercury for the system vinyl actate-2,4-dimethyl pentane. J. Chem. Eng. Data 514-515. 

Luminescence titrimetry has been developed chiefly for acid-base titrations. Therefore, fluorescence pH-indicators are now widely used. Their application is based on changes of fluorescence spectrum upon the addition of a proton or its loss. At present, over 200 fluorescence pH-indicators are available the structural formulae of the most the widely applied indicators are given in Table 8. Some of them (No. 2, 8, 9, 12, 16, 17, 23, 25 and 29) and also, primuline, tripaflavine, and rhodamine 6G are widely used as adsorption fluorescence indicators. The titration end point can be detected in this case because of the differences in of the indicator in the adsorbed state and in solution. Redox fluorescence indicators including rhodamines B and 6 G, 3,6-dihydroxy-phthalic acids, complexes of Ru(II) with 2,2 -dipyridyl or 1,10-phenanthroline and other... 

The analysis of phthalate metabolites has recently become of environmental concern. Primary metabolites of phthalate diesters are monoesters, in which one ester function is hydrolyzed. These monoesters have a carboxylic function that is currently derivatized to avoid adsorption during GC determination. Several derivatization agents have been used to block the free acid group. Methyl-esterification was used by Hashizume et al. and Suzuki et al. Silylation was preferred by Jonsson and Boren,and Jonsson et al. to simultaneously determine the diesters, monoesters and phthalic acid in the same analysis. Wahl et al. performed the analysis of three acid metabolites of... 

Figure 7. Adsorption of phthalic acid (H X) on y-AlgOg and its effect on...

The charge vs. pH Curves 1 and 2 were calculated from alkalimetric titration curves of AUOs in the absence and presence of phthalic acid, respectively. The adsorption of total phthalic acid (formation of =AIXH and =AIX ) was determined analytically (Curve 3). Curve 4 was calculated from Curves 1 and 3 assuming that uncharged =AIXH only is formed. Curve 5 was calculated with the equilibrium constants given in Equation 24, the acidity constants of phthalic acid (—log Ko = 2.8, —log Kag = 4.9) (19). 

Supported aqueous-phase catalysts (SAPC) can be seen as a special case of adsorption, whereby a water-soluble catalyst dissolved in a very polar solvent is adsorbed on a hydrophilic support forming a water film on the inner surface of the support [30,31]. In the case of supported liquid-phase catalysis (SLPC),the water film on the inner surface is replaced by a solvent of low vapor pressure (e.g.,phthalic acid esters) [2]. The reaction itself takes place in the supported hq-uid or at the interface of the supported liquid film, or in the gas phase or organic phase when dealing with SLPC or SAPC, respectively. The use of SLPC catalysts is generally restricted to the synthesis of low-boiling compounds. 

Ghromate adsorption by iron oxides is suppressed by a large excess of carbonate or silicate species. Gompetition between silicate and borate adsorption on ferrihydrite was reported by McPhail et ak (1972). Low levels of sulphate suppress uptake of phthalic and chelidimic acids by goethite (Ali Dzombak, 1996 a). 

One main characteristics of n-butane oxidation is the substantial absence of by-products of partial oxidation other than maleic anhydride (apart from a low amount of phthalic anhydride). This means that once the alkane has been adsorbed and transformed to the first intermediate species, the latter has to be quickly transformed up to the final stable product. If this requirement is not met, the adsorbed olefinic-like intermediate may desorb. This leads to a lower selectivity to the final desired product, because the olefin may be readsorbed on nonspecific oxidizing sites yielding other undesired products (aldehydes or acids), which can also be precursors for the formation of carbon oxides. Therefore, a rapid transformation of the adsorbed intermediates to oxidized products is necessary in order to obtain high selectivity to the desired product. In order to guarantee this selective pathway, the catalyst surface must provide the required arrangement of specific oxidizing sites the different functional properties must be arranged so as to provide an ensemble of sites (or, alternatively, sites with multifunctional properties) able to allow the reaction pathway from alkane adsorption and activation up to its transformation to the final product to be completed. 

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