Organic Acid, Chelating Agent

There are a very large number of solvents for removing iron oxide deposits. They include mineral acids, organic acids, chelating agents, and mixtures of these chemical classes. The choice of a particular solvent system depends on the metal of construction, exact type and density of the oxide, and cost and disposal considerations. 

Acid solutions Alkaline solutions Abrasives Organic compounds Chelating agents... 

The lanthanides form many compounds with organic ligands. Some of these compounds ate water-soluble, others oil-soluble. Water-soluble compounds have been used extensively for rare-earth separation by ion exchange (qv), for example, complexes form with citric acid, ethylenediaminetetraacetic acid (EDTA), and hydroxyethylethylenediaminetriacetic acid (HEEDTA) (see Chelating agents). The complex formation is pH-dependent. Oil-soluble compounds ate used extensively in the industrial separation of rate earths by tiquid—tiquid extraction. The preferred extractants ate catboxyhc acids, otganophosphoms acids and esters, and tetraaLkylammonium salts. 

Sca.Ie nd Sta.in Controllers. Polyacrjiates (low molecular weight) and organic phosphonates, eg, (l-hydroxyethyhdene)diphosphonic acid, prevent or control precipitation of CaCO by acting as chelating agents (qv) or dispersants (qv) to prevent excessive formation of hard scale by promoting crystal distortion. 

Either particulate sol or polymeric sol has been used for thin film coatings. The polymeric sol was fabricated by partial hydrolysis of corresponding metal alkoxide. If the rate of hydrolysis or condensation is very fast, then some kinds of organic acids, beta-dicarbonyls, and alkanolamines have been used as chelating agent in sol-gel processes to control the extent and direction of the hydrolysis-condensation reaction by forming a strong complex with alkoxide. [2]. 

In addition to phenolic substances, there are other components present in foods which have no antioxidant activity of their own, but which increase that of phenolic antioxidants. They are called synergists, and they should be accounted for in any discussion of antioxidant activity. Polyvalent organic acids, amino acids, phospholipids (lecithin) and various chelating agents belong to this group. Proteins may modify the efficiency of antioxidants as they react with the reaction products of both antioxidants and synergists. 

These compounds should be dissolvable in a clean-up solution containing a quaternary organic ammonium salt, or simply ammonium chloride [1749]. The solubilities of some selected particulate bridging agents are shown in Table 9-1. A chelating agent such as citric acid or its salts is also included in the clean-up solution. 

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