Neutralization process

Fundamental chemical physics descriptions of both ion and neutral processes. 

CoIIisional activation. An ion/neutral process wherein excitation of a (fast) projectile ion is brought about by the same mechanism as in collision-induced dissociation. (The ion may decompose subsequently). 

CoIIisional excitation. An ion/neutral process wherein the (slow) reactant ion s internal energy increases at the expense of the translational energy of either (or both) of the reacting species. The scattering angle can be large. 

Collision-induced dissociation (or decomposition), abbreviated CID. An ion/neutral process wherein the (fast) projectile ion is dissociated as a result of interaction with a target neutral species. This is brought about by conversion during the collision of part of the translational energy of the ion to internal energy in the ion. The term collisional-activated dissociation (or decomposition), abbreviated CAD, is also used. 

In the double-neutralization process, Na2SiFg is precipitated and removed by filtration at a pH of 3—4 (9). Upon raising the pH to 7—9, insoluble phosphates of Fe, Al, Ca, and Mg form and separate. Iron can be precipitated as hydrous ferric oxide, reducing the phosphate loss at the second filter cake. Both the fluorosihcate and metal phosphate filter residues tend to be voluminous cakes that shrink when dewatered recovery of soluble phosphates trapped within the cakes is difficult. 

Tellurium is stUl recovered in some copper refineries by the smelting of slimes and the subsequent leaching of soda slags which contain both selenium and tellurium. The caustic slags are leached in water and, using the controlled neutralization process, tellurium is recovered as tellurium dioxide. 

The neutralization process is not energy intensive added heat evaporates water formed in the reaction and water entering the system with the raw materials, which is 50% NaOH. The significant waste effluent contains 10—100 ppm NaCN and must be treated before disposal. 

In this dry process, ammonia gas passes into a molten mixture of potassium carbonate and charcoal. Although purity of the product is high, this process became obsolete because of the lower costs of the neutralization process. 

Three examples of simple multivariable control problems are shown in Fig. 8-40. The in-line blending system blends pure components A and B to produce a product stream with flow rate w and mass fraction of A, x. Adjusting either inlet flow rate or Wg affects both of the controlled variables andi. For the pH neutrahzation process in Figure 8-40(Z ), liquid level h and the pH of the exit stream are to be controlled by adjusting the acid and base flow rates and w>b. Each of the manipulated variables affects both of the controlled variables. Thus, both the blending system and the pH neutralization process are said to exhibit strong process interacHons. In contrast, the process interactions for the gas-liquid separator in Fig. 8-40(c) are not as strong because one manipulated variable, liquid flow rate L, has only a small and indirec t effect on one controlled variable, pressure P. 

The usefulness of Eq. (3.41) depends crucially on whether or not the sensitivity factor rjA depends on the presence of other elements in the surface ( matrix effects ). It is an experimental finding that in general neutralization depends only on the atomic number of the scattering center, and matrix effects occur rarely. An instructive example is the neutralization of He by A1 in the pure metal and in alumina. The slopes of the neutralization curves turn out to be the same for both materials, i. e. matrix effects are absent [3.143]. This is a strong indication that in the neutralization process not only the valence/conduction electrons, but also atomic levels below the valence/ conduction band are involved. 

Where dealkalization by acid cation exchange resin is employed, a small risk exists of contamination from acid breakthrough. A failure in the neutralization process may lead to acidic treated water entering the FW system, which reduces the FW pH and results in localized acid corrosion. 

Acid cleaning corrosion Results from both poor cleaning and poor neutralization processes... 

Dioxane forms by the chemical cleavage of two molecules of ethylene oxide from the parent ethoxylated alcohol. Dioxane is the undesirable byproduct. The amount of dioxane ranges from traces to hundreds, even thousands, of ppm (mg/kg) depending on raw material quality and sulfonation/neutralization process conditions. 

The neutralization process consists of an exothermic reaction between a neutralizing agent and either sulfonic acid (e.g., LAB, a-olefins, FAME) or acid sulfate (e.g., primary alcohols, ethoxylated alcohols). Neutralization can be carried out after prolonged storage if the acid stability permits (LAS, FAMES). 

The positive charge should reside on a complex entity, and there is no ready means for assessing the products of the neutralization process. Although we know that neutralization must yield 3.8 intermediates/100 e.v., there is no chemical evidence for their contribution to the product distribution. This cannot be interpreted by neutralization yielding predominantly hydrogen atoms, ethyl radicals, or methyl radicals. One can quantitatively account for these intermediates on the basis of the distribution of primary species and second- and third-order ion-molecule reactions (36). 

Authors have proposed a novel process not to dispose to landfill sites both waste PVC and waste glass but to utilize them to produce fuel and neutralize each other at the same moment. It has been successfully demonstrated that hydrogen chloride produced during flash pyrolysis of PVC was completely neutralized by the fixed glass bed and thus chlorine-lree fuel was produced [1-2]. To carry forward our proposed process we need to know the kinetics of the neutralization process. Also we have to solve the problem of formation of metal chlorides in the product char during pyrolysis of PVC, which is a critical issue for its thermal utilization. Consequently, in the present study the evaluations of neutralization kinetics of glass cullets and the decomposition of CaCl2 in char by steam were conducted. 

The rate of drug release (E) from the eroding matrix is controlled by (a) the chemical properties of the system - the hydrolytic and the neutralizing process at the boundary of the device, catalytic degradation of the polymer and the intrinsic backbone reactivity, and (b) several concomitant physical processes such as water diffusivity, water solubility, water partitioning, etc. 

Through the late 1980s, spent pickle liquor was traditionally land disposed by steel manufacturers after lime neutralization. The lime neutralization process raises the pH of the spent acid and makes heavy metals in the sludge less likely to leach into the environment. Today, however, some of the spent pickle liquor can be recycled or regenerated on-site by steel manufacturers.5... 

An important gastric secretion is the hydrochloric acid that performs a number of functions in the stomach. This stomach acid is neutralized by pancreatic bicarbonate ion in the duodenum. Excess acid in the chyme stimulates chemoreceptors in the duodenum. This receptor stimulation elicits reflex inhibition of gastric motility. Excess acid also causes the release of secretin and gastric inhibitory peptide from the duodenum. These hormones contribute to inhibition of gastric contractions so that the neutralization process may be completed before additional acid arrives in chyme from the stomach. 

A much more detailed and time-dependent study of complex hydrocarbon and carbon cluster formation has been prepared by Bettens and Herbst,83 84 who considered the detailed growth of unsaturated hydrocarbons and clusters via ion-molecule and neutral-neutral processes under the conditions of both dense and diffuse interstellar clouds. In order to include molecules up to 64 carbon atoms in size, these authors increased the size of their gas-phase model to include approximately 10,000reactions. The products of many of the unstudied reactions have been estimated via simplified statistical (RRKM) calculations coupled with ab initio and semiempirical energy calculations. The simplified RRKM approach posits a transition state between complex and products even when no obvious potential barrier... 

There are basically two kinds of neutralization processes for the cation, reaction with the electron and with a negative ion. In each case, it may be assumed that neutralization will occur with the parent or fragment ion of lowest energy. It is believed that the various degradation processes for the cation-fragmentation, ion-molecule reaction, and so forth—are much faster than the neutralization process. In addition, one considers charge transfer, without decomposition, from the cation formally as a neutralization of that species. To effect that, of course, one... 

Invented by H. Y. Castner in 1894. Operated first at Frankfurt-am Main, in 1899, and thereafter in several other counties, until abandoned in the 1960s in favor of the neutralization process. 

As extensive tables of reliable sputter yields are available, SNMS is much more suitable than SIMS for quantitative work. Interestingly, ionic solids also give significant yields of secondary neutrals, underlining the fact that neutralization processes at the surface are also important for non-metallic samples. 

The probability that neutralization takes place depends on the energy of the ion, simply because a slow ion is in the vicinity of an atom for a longer time. The maximum distances at which neutralization processes are thought to occur are on the order of 0.2 nm for Auger and 0.5 nm for resonance neutralization. 

Liquid carbon dioxide is decomposed efficiently by ionizing radiation79. The decreased radiation stability of the liquid phase compared to the gas phase has been attributed to the much smaller contribution of ion-molecule reactions to radiolysis in the condensed phase, where an efficient geminate charge neutralization process is likely to minimize the occurrence of such processes. Ion-molecule reactions are probably responsible for the rapid reoxidation observed in the gas phase. The yields of CO, 02 and 03 from the y-radiolysis of liquid C02 can be... 

The preparation of colloidal particles can be performed by the addition of a well-defined amount of soda corresponding to the second intermediate zone. The neutralization process corresponds to simultaneous titrations of free acidity brought by nitric acid and a palladium complex according to the following reactions ... 

In this section, we shaU outline a many-electron treatment of charge transfer, similar in spirit to that of Tully, which enables different charge-exchange mechanisms to be incorporated in the formalism simultaneously. Although we shall concentrate on the TDAN model of resonant neutralization and negative ionization, we shall indicate how other neutralization processes can be included, and the approach for the reverse process of positive ionization will be fairly apparent. 

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