Precipitation phenomenon

In a first part of this paper, we will discuss results of a 27A1 NMR study of the binding of Al ions on acrylamide-acrylic acid copolymers as a function of pH, at the light of a simple electrostatic model. The second part deals with the phase diagrams, physical gelation and precipitation phenomenon, for different copolymer compositions and under various conditions of concentrations, pH and salinity. 

Acid rain the precipitation phenomenon that incorporates anthropogenic acids and other acidic chemicals from the atmosphere to the land and water (see also Acid deposition). 

The composition of liquid-water clouds and processes responsible for this composition are of obvious current interest in conjunction with the so-called acid precipitation phenomenon since clouds constitute the immediate precursor of precipitation. Additionally, cloud composition is of interest because impaction of cloud droplets on surfaces may directly deliver dissolved substances onto natural or artificial materials. In-cloud processes also influence clear-air composition since dissolved substances resulting from such reactions are released into clear air as gases or aerosol particles upon cloud evaporation. It is thus desired to gain enhanced description of the composition of clouds and the mecha-... 

In hardened lateritic soils, the binding phase is so small that it cannot be isolated and identified. However, needle-shaped crystalhne growth was found in silicate-bonded red mud [22]. Such direct evidence is not available for natural soils, but the fact that soils harden when they are rich in alumina after wetting and drying cycles suggests that the dissolution-precipitation phenomenon controls hardening of these lateritic sods. 

We have completed experiments label the ionic domains. We have found evidence of a precipitation phenomenon of particles of iron oxide or hydroxide when an iron form of membrane was exchanged by different other ions like K+, Na+, etc. We therefore have analyzed these particles by different techniques -like X rays, Mossbauer spectroscopy, magnetic measurements and electron microscopy- with two goals in mind. First of all the formation of ultra thin particles is very important in different domains and especially in catalysis when these membranes are used in the solid polymer electrolyte process. Second, we expect some correlation between the sizes and distribution of precipitates with the starting ionic domains. 

The concentrations depend on the solution composition, for instance cadmium sulfide films prepared at lower pH are close to stoichiometry whereas those prepared at higher pH have a ratio [Cd]/[S] about 1.1 due to the presence of hydroxide species (Cd(OH)2) [45]. The formation of other hydroxy-sulfide films (ofZn [105,106], In [116], Sn [116]) can be also related to competitive precipitation phenomenon. As a consequence, the analysis of the solubility diagrams of all solid compounds in a given CBD system is a useful tool to improve the composition control of the films. This approach... 

THE ACIDIC PRECIPITATION PHENOMENON. A STUDY OF THIS PHENOMENON AND OF A RELATIONSHIP BETWEEN THE ACID CONTENT OF PRECIPITATION AND THE EMISSION OF SULFUR DIOXIDE AND NITROGEN OXIDES IN THE NETHERLANDS... 

To describe the acid precipitation phenomenon, a number of techniques have been used to quantify the acidity, identify the acidic and basic components and to identify the sources of acidity. The methodology used is often determined by the available data. Although all valid models should reach consistent conclusions, the sensitivity of each technique to random and systematic errors should be determined to provide confidence limits for the results. This paper examines the acidity of precipitation in southern California with the charge and conductivity balances, direct measurements, source strength calculations and scavenging models. Some of the limitations of each approach are also discussed. 

The Acidic Precipitation Phenomenon A Study of This Phenomenon and the Relationship between the Acid Content of Precipitation and the Emission of Sulfur Dioxide and Nitrogen... 

The precipitation phenomenon is seen as agglomeration, which is represented by Smoluchowski s equation (Mullin, 1993). 

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