The enthalpy of sorption of glycine from aqueous solutions by carboxyl cationites in the copper and mixed forms

The influence of glycine solution acidity on glycine interactions with carboxyl cationites in the copper and mixed sodium-copper forms was studied by the calorimetric, sorption, and IR spectroscopy methods. The enthalpies of sorption of glycine on KB-2 and KB-4 at various pH were determined.     

Adsorption of some bivalent heavy metal ions from aqueous solutions by manganese nodule leached residues

The leached residue, generated after selective extraction of Cu, Ni, and Co in sulfur dioxide-ammonia leaching of manganese nodules, was characterized and batch isothermal adsorption experiments were conducted at ambient temperature to evaluate the effectiveness of the water-washed leached residue for removal of different bivalent metal ions from aqueous synthetic solutions. The effects of pH, initial metal ion concentrations, amount of adsorbent, interfering ions, and heat treatment were also investigated. The uptake of metal ions increased with increasing pH. Under identical conditions the adsorption capacity increased in the order Cd(2+)相似文献   

Ionic association in aqueous solutions of strong electrolytes

A more accurate calculation of relaxation effects obtained with the standard Debye-Hückel-Onsager model has been presented recently and is here applied to several aqueous 1:1 electrolytes. The variation of the standard deviation between calculated and observed equivalent conductivities withK _A leads to an ill-defined minimum; but, where data over a wide concentration range are available, the minimum corresponds to values of the contact distancea which approximate to estimates from ionic dimensions. It is therefore proposed that, although preciseK _A values from conductance cannot be determined, the most probable values are those associated with realistic estimates ofa. When data cover a limited concentration range, minimum standard deviations are often indeterminate or vary greatly for duplicate runs. It is shown that reasonable values ofK _A can be obtained from such data if comparison is made at estimated values ofa.Notation The symbols not defined in the text are the following b e ²/kTa for 1:1 electrolytes - e electronic charge - k Boltzmann gas constant - T absolute temperature - dielectric constant of solvent - –(3/2y)(_e0/₀)     

甘氨酸从水到酰胺衍生物水溶液中的迁移焓

用RD496-Ⅱ型微量热量计测定了298.15 K甘氨酸在N-甲基甲酰胺（NMF）,N, N-二甲基甲酰胺（DMF）,N-甲基乙酰胺（NMA）,N, N-二甲基乙酰胺（DMA）水溶液中的溶解焓,计算了甘氨酸从水到四种酰胺衍生物水溶液中的迁移焓（ΔtrH）。根据结构水合作用模型讨论了酰胺的结构对甘氨酸迁移焓的影响。实验结果表明：甘氨酸在酰胺衍生物水溶液中的迁移焓均为正值,并且随着溶液浓度增大而增大。比较甘氨酸在甲酰胺（FA）和乙酰胺（AD）水溶液中的迁移焓,发现在不同酰胺水溶液中迁移焓大小为：DMA>NMA>DMF>NMF>AD>FA。甘氨酸与甲酰胺之间以亲水-亲水相互作用为主,与其它酰胺之间以亲水-疏水作用为主。     

Immersion enthalpy of carbonaceous samples in aqueous solutions of monohydroxilated phenols

The immersion enthalpies of modified activated carbons were determined, with commercial Carbochem^TM–PS230 (CAG) as the initial activated carbon, which was modified by: chemical treatment with HNO₃ 7 mol L⁻¹ (CAO) and thermal treatment under flow of H₂ (CAR) in function of the adsorbed quantity of monohydroxilated phenols, catechol, resorcinol and hydroquinone at a pH of 7 in aqueous dissolutions in order to characterize the solid–solution interaction and evaluate the influence of the chemical characteristics of the activated carbon in the phenol adsorption. The results show a variation in the immersion enthalpy in function of the adsorbed quantity of phenol and the initial dissolution concentration; which shows that the intensity of the interaction changes in function of the composition of the liquid phase. The immersion enthalpies present the following arrangement: catechol > resorcinol > hydroquinone, with a −ΔH_inm of 35.7; 30.8 and 24.6 Jg⁻¹, respectively, at a pH of 7 for a 100 mg L⁻¹ phenol monohydroxilated solution.     

Influence of water activity on the rate of dihydrogen oxidation by metal complexes in aqueous solutions of electrolytes

Strong interaction of Pt with a TiO₂ support (reductive high-temperature treatment) is shown to increase the catalytic activity due to a decrease in CO coverage of the active Pt surface.

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Molecular dynamics simulation of aqueous solutions of glycine betaine

Molecular dynamics simulation is used to investigate hydration properties of glycine betaine in a large range of solute concentrations. Statistical analyses of the system trajectories evidence microscopic details suggesting an interpretation of experimental results recently obtained for aqueous solutions of trimethylamine-N-oxide, a bioprotectant closely related to glycine betaine.     

Excess enthalpy and entropy of aqueous tetramethylguanidinium methanesulfonate and trifluoromethanesulfonate solutions

Relative apparent molal heat contents, φ_L, are reported for the tetramethylguanidinium salts of methanesulfonic (MS) and trifluoromethanesulfonic (TFMS) acids. Relative partial molal heat contents, L?₂, are calculated and combined with previously reported activity coefficient data, to yield excess entropies. It is found that the values of L?₂ make the principal contribution to the excess entropies of Me₄GuMS solutions while the excess free energies, as calculated from activity coefficients, make the greatest contribution to the excess entropies of Me₄GuTFMS solutions.     

Prediction of activity coefficients of electrolytes in aqueous mixed electrolyte solutions

A method is proposed for calculating the activity coefficient of constituent electrolytes in aqueous mixed electrolyte solutions. The equations derived from the knowledge of Λ^*, the overall reduced ionic activity coefficient in a mixture, are found to predict activity coefficients accurately up to an ionic strength of 12 mol kg⁻¹ and a temperature of 473 K.