Lime potential

The pH — pCa value of equation 5.11 is termed the lime potential of a soil because it relates directly to the activity of Ca(OH)2, a form of lime, in soil solution. Lime potential has been shown to be less dependent than pH on the electrolyte concentration of soils, and is therefore argued to be a more diagnostic measure of a soil s... 

From equation 5.21 for Al —Ca exchange and equation 5.19 for gibbsite solubility, derive an equation that relates percent Ca " saturation of exchange sites to lime potential. (Assume an ionic medium of 0.01 MCaCh and Kj = 30 for the exchange reaction in this medium.)... 

The ions in the soil solution constitutes the active acidity and are measured directly as soil pH values. On the other hand the adsorbed H+ ions held on exchange sites are not subject to pH measurements are termed as reserve acidity , both the forms contribute to soil acidity. Thus soil pH does not reflect the total acidity. However a suitable index which takes into account the reserve acidity of soil is the lime potential, which is calculated as follows ... 

The lime potential is a very reliable estimate to predict the buffering capacity of soils. Smaller the value of lime potential, greater will be the buffering capacity of the soil. 

In practice soil is shaken with a calcium chloride solution of known strength (1 2 soiksolution ratio) and activity of Ca + ions and the pH of the suspension is measured. Lime potential is calculated as (measured pH - 1.14), 1.14 being the value of k2pCafor O.Ol(M) CaClg solution. The use of O.Ol(M) CaClg solution as an extractant simulates the electrolyte level of non-saline soil at optimum field water content and more so the H+ ion environment existing in the soil solution-plant root system. 

CN] —> I + CN. Wavepacket moves and spreads in time, with its centre evolving about 5 A in 200 fs. Wavepacket dynamics refers to motion on the intennediate potential energy surface B. Reprinted from Williams S O and lime D G 1988 J. Phys. Chem.. 92 6648. (c) Calculated FTS signal (total fluorescence from state C) as a fiinction of the time delay between the first excitation pulse (A B) and the second excitation pulse (B -> C). Reprinted from Williams S O and Imre D G, as above. 

Th c Newton-Raph son block dingotial method is a second order optim izer. It calculates both the first and second derivatives of potential energy with respect to Cartesian coordinates. I hese derivatives provide information ahont both the slope and curvature of lh e poten tial en ergy surface, Un like a full Newton -Raph son method, the block diagonal algorilh m calculates the second derivative matrix for one atom at a lime, avoiding the second derivatives with respect to two atoms. 

If a plant cmshes to obtain stone of 0.6 and 7.6 cm for lime-kiln feed, coarse aggregate, or fluxstone, much undersized material is also produced. Oversized material can be reduced by recycling through the cmsher system, but the subsized stone, called spall, is wasted in a spall pile. Such spalls have potential value as by-products for use as, eg, asphalt (qv) filler. 

Other developing or potential appHcations for lime are neutralization of tail gas from sulfuric acid plants, neutralization of waste hydrochloric and hydrofluoric acids and of nitrogen oxide (NO ) gases, scmbbing of stack gases from incinerators (qv), and of course, from small industrial coal-fired boilers. 

Ammonium Ion Removal. A fixed-bed molecular-sieve ion-exchange process has been commercialized for the removal of ammonium ions from secondary wastewater treatment effluents. This application takes advantage of the superior selectivity of molecular-sieve ion exchangers for ammonium ions. The first plants employed clinoptilolite as a potentially low cost material because of its availability in natural deposits. The bed is regenerated with a lime-salt solution that can be reused after the ammonia is removed by pH adjustment and air stripping. The ammonia is subsequentiy removed from the air stream by acid scmbbing. 

Raw Material Proportions. The three main considerations in proportioning raw materials for cement clinker are the potential compound composition the percentage of Hquid phase at clinkering temperatures and the bumabiUty of the raw mix, ie, the relative ease, in terms of temperature, time, and fuel requirements, of combining the oxides into good quaUty clinker. The ratios of the oxides are related to clinker composition and bumabiUty. For example, as the CaO content of the mix is increased, more C S can be formed, but certain limits cannot be exceeded under normal burning conditions. The lime saturation factor (LSF) is a measure of the amount of CaO that can be combined (20) ... 

Industrial by-products are becoming more widely used as raw materials for cement, eg, slags contain carbonate-free lime, as well as substantial levels of silica and alumina. Fly ash from utility boilers can often be a suitable feed component, because it is already finely dispersed and provides silica and alumina. Even vegetable wastes, such as rice hull ash, provide a source of silica. Probably 50% of all industrial by-products are potential raw materials for Pordand cement manufacture. 

Reports of maintenance on components are potential sources of data on failures, repair limes and unavailability due to maintenance. 

In 1931 Ing pointed out that formula (II) and (III) do not contain methyl or potential methyl groups in j ositions 6 and 8 which they occupy in cytisoline. Further, a partially reduced quinoline ought to oxidise easily to a benzenecarboxylic acid and so far the only simple oxidation, products recorded from cytisine were ammonia, oxalic acid and isovaleric acid. Distillation of cytisine with zinc dust or soda-lime yields pyrrole and pyridine, but no quinoline. On these grounds Ing suggested that cytisine should be formulated without a quinoline nucleus, and that the reactions which indicate the presence of an aromatic nucleus in the alkaloid can be accounted for by an a-pyridone ring. This a-pyridone nucleus can... 

Chemical intakes are calculated using equations that include variables for e.xposure concentration, contact rate, e.xposure frequency, e.xposure duration, body weight, and exposure averaging lime. The values of some of these variables depend on site conditions and the characteristics of The potentially c.xposcd population. 

The potential for noncarcinogcnic health effects is evaluated by comparing iui exposure level over a specified lime period (c.g., lifetime) with a reference dose derived for a similar exposure period. The ratio of exposure to toxicity in called a liazard quotient and, when it is greater tlien unity tlierc is a higher level of concern for potential noncancer effects. 

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