Chelating agents phosphates

The traditional HDS catalysts are CoMo or NiMo based catalysts. Highly dispersed molybdenum sulphide exhibits a low but stable catalytic activity in a sulfur-containing environment. By adding the promoter elements, cobalt or nickel, in an atomic Co/Mo or NiMo ratio of 0.3 to 0.5 a ten-fold increase in activity could be achieved [1], Further improvements were made by addition of chelating agents, phosphate, and fluorine [2]. 

Chang, D.M. Binding of Free Calcium Ions in Aqueous Solution Using Chelating Agents, Phosphates and Poly(Acrylic Acid), American Oil Chem. Soc. (1983) 60, 618-22. 

Polymers may act as weak chelating agents and thus retain hardness salts in solution in BW. In this event the hardness as determined by EDTA titration is measurable, particular attention should be given to maintaining the recommended level of carbonate or phosphate. In appropriate circumstances, chelating agents may be used in place of phosphate. 

Fluorinated phosphonates exhibit interesting properties as enzyme inhibitors, chelating agents or as fuel cell electrolytes [29] however, only few methods of preparation for these compounds are available. Burton et al. [30] developed several methods to prepare fluorinated phosphates which involve phosphonyl, and likely phosphoranyl radicals as chain carriers (Scheme 11). 

Treatment additives, chelating agents, and clay minerals can be added to a system to bind to metals and reduce metal mobility. Treatment additives, such as carbonates, phosphates, and hydroxides, form insoluble precipitates with metals, thus decreasing their bioavailability. Jonioh et al.141... 

Arsenic uptake in rabbit intestine is inhibited by phosphate, casein, and various metal-chelating agents (USEPA 1980). Mice and rabbits are significantly protected against sodium arsenite intoxication by (V-(2,3-dimercaptopropyl)phthalamidic acid (Stine et al. 1984). Conversely, the toxic effects of arsenite are potentiated by excess dithiols, cadmium, and lead, as evidenced by reduced food efficiency and disrupted blood chemistry in rodents (Pershagen and Vahter 1979). 

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