Physico-chemical interactions

Some Physico-chemical Interactions of Paraquat with Soil Organic Materials and Model Compounds. I. Effects of Temperature, Time and Absorbate Degradation on Paraquat Adsorption, I. G. Bums, M. H. B. Hayes, and M. Stacey, Weed Res., 13 (1973) 67 -78. 

Prahalad, A.K. and G. Seenayya. 1989. Physico-chemical interactions and bioconcentration of zinc and lead in the industrially polluted Husainsager Lake, Hyderabad, India. Environ. Pollut. 58A 139-154. 

These data imply that aromatic hydrocarbons incorporated into sediments are not preferentially accumulated in relation to increased alkyl substitution, as shown with dietary and seawater exposures. Moreover, the apparent lack of accumulation of the fluorene and phenanthrene suggests that unsubstituted aromatic hydrocarbons having more than two benzenoid rings may not be readily sequestered by fish exposed to petroleum-impregnated sediment. These differences are presumably related, at least in part, to physico-chemical interactions of aromatic hydrocarbons with sediment matrices that regulate their bioavailability. 

Burclul SM, Hayes MHB, Greenland DJ (1981) Adsorption. In Greenland DJ, Hayes MHB (eds) Chemistry of soil processes. WUey, New York, pp 224 00 Bums IG, Hayes MHB, Stacey M (1973) Some physico-chemical interactions of paraquat with soil organic materials and model compounds. 11. Adsorption and desorption equilibria in aqueous suspensions. Weed Res 13 79-90... 

In addition to surface analytical techniques, microscopy, such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), scanning tunneling microscopy (STM) and atomic force microscopy (AFM), also provide invaluable information regarding the surface morphology, physico-chemical interaction at the fiber-matrix interface region, surface depth profile and concentration of elements. It is beyond the scope of this book to present details of all these microscopic techniques. 

Interactions between chemicals may be of a physico-chemical and/or biological nature. Examples of physico-chemical interactions are the reaction of nitrite with aUcylamines to produce carcinogenic nitrosamines, and the binding of toxic chemicals to active charcoal resulting in a decreased absorption from the gastrointestinal tract. It is held that physico-chemical interactions will normally only occur at high doses and therefore are of lesser importance for low-dose scenarios. Physico-chemical interactions will therefore not be considered in any detail in this book. 

Abstract This paper is concerned with the experimental identification of some chemo-poroelastic parameters of a reactive shale from data obtained in pore pressure transmission - chemical potential tests. The parameter identification is done by matching the observed pressure response with a theoretical solution of the experiment. This solution is obtained within the framework of Biot theory of poroelasticity, extended to include physico-chemical interactions. Results of an experiment on a Pierre II shale performed in a pressure cell are reported and analyzed. 

In this paper, we analyze this experiment within the framework of Biot theory of poroelasticity, extended to include physico-chemical interactions, and study the parameters that are influencing the fluid pressure response in the downstream reservoir due to hydraulic and chemical loadings. 

The Biot theory of poroelasticity ([4, 2]) can be extended to account for the physico-chemical interactions taking place between the dissolved salt, pore fluid, and a chemically active shale ([8, 9]). For example, a sample of reactive shale surrounded by a fluid initially in thermodynamic equilibrium with the saturating fluid experiences a contraction (e < 0) accompanied by a decrease... 

The set of constitutive parameters contains the (drained) elastic volumetric compliance C and two poroelastic constants the Biot stress coefficient b, and the unconstrained storage coefficient Sa = d(/dp a which can be expressed as So- = bB 1C ([13]), where B is the Skempton pore pressure coefficient. The other three parameters, a, f3, and 7 quantify the physico-chemical interactions. Both a and (3 are constrained to vary from 0 when there is no chemical interaction to 1 when the salt ions are trapped in the pore network (this limiting case is referred to as the perfect ion exclusion membrane model ). The coefficient 7 can simply be approximated by 7 x0/n, where n is the porosity of the shale. 

The LC methods discussed before were based mainly on physico-chemical interactions between the solute on the one hand and the two chromatographic phases on the other. Although we have seen that in RPLC the degree of ionization of weakly acidic or basic solutes may be a major factor in the control of retention and selectivity, the ionic species themselves were not exploited purposefully to realize or enhance the separation. In fact, in a typical RPLC system all fully ionized solutes will show little retention and therefore little resolution can be achieved between different ions. The methods described in this section make positive use of the ionic character of solutes to create a chromatographically selective system. 

Considering now the chemical or physico-chemical interactions between the supported phase and the support, it is clear that a change of reactivity will be observed if the supported phase reacts chemically with the carrier for example, nickel can combine with silica to make some hydroxysilicate compound when the deposition-precipitation method is used for preparation. The reactivity of the hydroxysilicate with hydrogen during activation by reduction is very different (actually lower) compared to that of nickel oxide. But careful analysis of the various examples mentioned in literature shows that quite different situations may exist. 

Plant cell walls are the source of lignocellulosic materials, also known as biomass, whose structure is chiefly represented by the physico-chemical interaction of cellulose (a linear glucose polymer), with hemicellulose (a highly... 

The physico-chemical interactions that can be exploited in the selection and optimisation of these processes are discussed below. We will reserve for future communications a detailed discussion of the technological aspects and potential problems in the implementation of reversed micellar extraction of bioproducts in large-scale continuous operations, these topics being beyond the scope of this overview. 

This study demonstrated the influence of natural colloids from wine (mannoproteins released from yeast) on the volatility of aroma compounds and therefore the possible role of these minor components of a wine matrix on sensory properties of wine. The physico-chemical interactions between aroma substances and exocellular yeast material depend on the nature of volatile compounds and of the macromolecules. 

The physico-chemical interactions between aroma compounds and other components depend on the nature of volatile compounds. The level of binding generally increased with the hydrophobic nature of the aroma. However interactions also depend on the nature of macromolecules such as yeast walls, mannoproteins, bentonite or smaller molecule such as ethanol. As a function of the nature of non-volatile component, the increase or decrease in the volatility of aroma compounds can influence largely the overall aroma of wine. 

This result suggests that phototransformation of biolabile substances proceeds mainly via direct photoreactions, while photo-induced interactions with other Hght-absorbing constituents of natural waters are of negligible importance. In contrast, in experiments with fresh algal extract irradiated in presence of humic substances (Tranvik and Kokalj, 1998), irradiation decreased susceptibihty of the substrate to subsequent mineralization by bacteria. The decreased respiration was demonstrated to be caused by photo-induced, physico-chemical interactions between algal extract and humic substances. 

Dye molecules, filling in SMV space, are connected with polymer molecules by forces of physico-chemical interaction, at the expence of which load on cross-section of the fibre is distributed more uniformly during the loading of dyed fibre and this leads to hardening of fibres. 

When Vr/Vm is greater than 1, the behaviour of the compound on the column no longer follows rigidly the mechanism of size exclusion but as in HPLC it undertakes physico-chemical interactions with the support (AT > 0). 

When one talks about reversibility of the Rehbinder effect, the presence of a thermodynamically stable interface between mutually saturated solid phase and the liquid, as well as complete disappearance of these effects upon the removal of the medium (e.g. by evaporation) are implied. These features emphasize principal difference between the Rehbinder effect and corrosive action of the medium. At the same time, one has to realize that it is not possible to draw here a distinct border line. The term disintegration covers a broad range of processes from idealized cases of purely mechanical breaking to destruction by corrosion or dissolution. The Rehbinder effect, i.e. the lowering of strength due to adsorption and chemisorption, stress-caused corrosion, and corrosion fatigue, occupies some intermediate place between these extremes. All these phenomena represent a certain degree of combination between the mechanical work performed by external forces and chemical (physico-chemical) interaction with the medium. 

Although this book significantly differs from the earlier Colloid Chemistry textbook, it nevertheless focuses on the specifics of educational and research work carried out at the Colloid Chemistry Division at the Chemistry Department of MSU. Many results presented in this book represent the art developed in the laboratories of the Colloid Chemistry Division, in the Laboratory of Physical-Chemical Mechanics (headed by E.D. Shchukin since 1967) of the Institute of Physical Chemistry of the Russian Academy of Science, and in other research institutions and industrial laboratories under the guidance of the authors and with their direct participation. Special attention is devoted in the book to the broad capabilities that the use of surfactants offers for controlling the properties and behavior of disperse systems and various materials due to the specific physico-chemical interactions taking place at interfaces. At the same time the authors made every effort to avoid duplication of material traditionally covered in textbooks on physical chemistry, electrochemistry, polymer chemistry, etc. These include adsorption from the gas phase on solid surfaces (by microporous adsorbents), the structure of the dense part of the electrical double layer, electrocapillary phenomena, specific properties of polymer colloids, and some other areas. 

As mentioned earlier, the mechanism of gas separation by non-porous membranes basically is different from the one in microporous membranes. Gas molecules actually dissolve and diffuse in the dense membrane matrix. Differences in permeability, therefore, will result not only from diffusivity (mobility) differences of the various gas species but also from differences in physico-chemical interactions of these species within the polymer, determining the amount of gas that can be accommodated per unit volume of the matrix. 

Other applications of DSC and other TA techniques to the pharmaceutical industry include physico-chemical interactions (275), polymorphism in triglyceride suppository formulations (276) drug-excipient interactions (277), and many more. Reviews of the applications of DTA/DSC and different techniques to pharmaceuticals include those by Brennan (278), Daly (279), and others (280). 

The enormous number of chemical reactions and other chemical and physico-chemical interactions in waters considerably complicate their exact description. There are various co-existing dynamic equilibria in waters resulting from the protolytic, complex-forming, oxidation-reduction, polymerization, photochemical, hydrolytic, and other reactions. Inorganic and organic substances are determined in waters both quantitatively and qualitatively. The chemical characteristics and properties of water do not depend... 

Phase diagrams provide fundamental information about the physico-chemical interaction between the substances in a mixture to... 

Adsorption is the physico-chemical interaction between solutes and the membrane. The adsorption of organics, or more specifically humic substances, is considered a major fouling mechanism in water treatment. NOM can either adsorb in the structure of the cake and give the cake cohesion, or in the bulk of the membrane. These interactions are strongly influenced by membrane solute affinities and the... 

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