Ion scrubbing

As a means for cleaning surfaces by ion scrubbing, physical sputtering, or plasma etching. 

The electron-ion recombination process occurs mostly on surfaces and releases the energy taken up in the ionization process. This recombination, and the associated energy release, aids in desorption in the ion scrubbing of surfaces (Sec. 13.11.1). 

Plasmas enhance desorption from surfaces by ion scrubbing, photodesorption, and heating of surfaces due to radiation and recombination. Inert gas plasmas are used to desorb (ion scrub) contaminants such as water vapor. Reactive gases such as oxygen and hydrogen are used to chemically react with and volatilize contaminants such as hydrocarbons. 

Plasmas in contact with surfaces are very effective in desorbing adsorbed species by ion scrubbing (Sec. 13.10). 

Contaminants on surfaces in the deposition chamber are easily desorbed in plasma-based sputtering due to heating and ion scrubbing. 

Plasmas in contact with surfaces will ion scrub the surface, giving desorption of adsorbed surface species such as water vapor. The plasma will activate any reactive or potentially reactive species. The reduced pumping speed that is usually used in establishing a plasma... 

In situ cleaning (PVD technology) Cleaning in the deposition system. Examples Ion scrubbing reactive plasma cleaning sputter cleaning. 

Ion scrubbing (cleaning) The desorption of adsorbed species from a surface in contact with a plasma under the action of ions accelerated across the plasma sheath. 

This wastewater stream contains lead (Pb) salts and chlorinated hydrocarbons generated from corrosion of the anodes as well as asbestos particles generated as a result of degradation of the diaphragm with use. Wastewater is also generated from the scrubber where the chlorine is wet scrubbed and from the ion exchange resin used to purify the brine solution. These wash water often contains dilute hydrochloric acid with small amounts of dissolved calcium magnesium and aluminum chloride. Like in other cells, the scrubber water also contributes to the wastewater stream. 

CEC [Chisso Engineering Company] A process for removing oxides of nitrogen from flue-gases by scrubbing with an aqueous solution containing ferrous ion and ethylenediamine tetra-acetic acid (EDTA). An iron nitrosyl compound is formed. Developed by Chisso Engineering Company, Japan, and piloted in France and Japan. 

The electron-rich oxygen anions exhibit basic electron donor capacity. Basic metal oxides are commonly used for neutralizing or scrubbing acidic gases. Alkaline earth metal oxides have been used for the removal of NOx. The surfaces of cubic alkaline metal oxide such as MgO, CaO, and BaO are dominated by the Lewis basicity of surface oxide anions. The basicity increases down the alkaline earth family as the metal ion radii become larger and the chaige on the metal ion becomes more positive. 

The absorption of sulfur dioxide into flue gas scrubbing slurries is enhanced considerably because of the reactions of dissolved sulfur dioxide with various dissolved alkaline species. The alkaline species of interest are the following ions and ion-pairs OH-, SO", HCO-, CO--, MgS0°, MgC0°,... 

The most significant chemical equilibria present in flue gas scrubbing slurries are outlined. Expressions for temperature dependent equilibrium constants are presented that are suitable for the temperature ranges encountered in scrubbing applications. Expressions for activity coefficients of ions and ion-pairs are presented that are suitable for the ranges of ionii strengths encountered for this type of applications. 

A typical colorimetric analyzer is illustrated schematically in Figure 6-8. Sample air is drawn at a metered rate into a contact column, where the air is scrubbed with a metered flow of potassium iodide buffered at a pH of 6.8. The reaction of oxidants with the potassium iodide solution produces the yellow triiodide ion (I, ). The colored solution flows to a colorimeter cell, where the absorbance of the triiodide ion is measured... 

The absorbent in the CANSOLV SO2 Scrubbing System accumulates nonregenera-ble salts [also called Heat Stable Salts (HSS)] and dust that are removed from the gas over time. These contaminants must be removed from the absorbent continuously to avoid excessive build-up. An APU incorporates both an ion exchange unit (IX) for the removal of HSS and a filtration unit for the removal of dust. 

Air is passed through a chamber where a mist of water or other aqueous solution is used to scrub out species of interest. The solution is then analyzed for the corresponding ions. As discussed shortly, this method has been used for several atmospheric gases, including HN03, carboxylic acids, and carbonyl compounds. 

ClNOz, and C10N02. The air then passes into a second chamber with an alkaline scrubbing solution, which absorbs most of the Cl2 and some HOC1. The two solutions are analyzed for chloride ion by ion chromatography. Differences in the chloride ion concentrations in the acid compared to the alkaline solutions provide a measure of chlorine-containing inorganics other than HC1. 

Scrubbers. Mist chamber scrubbers have also been used for HN03. The airstream passes through a Teflon filter to remove particles and then encounters a mist of water that scrubs the HN03 out of the air. The nitrate concentration is measured in the aqueous scrubbing solution using ion chromatography (Talbot et al., 1990). 

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