Chelating agents sodium oxalate

Extraction with cold/hot solutions of chelating agents sodium hexamethaphosphate ammonium oxalate EDTA... 

The mash from the Streptomyces aureofaciens fermentation broth is acidified and filtered. The filtrate is adjusted to the desired pH, usually 7-8.5, and various flocculating or chelating agents may be added (e.g., vinyl acetate-maleic anhydride copolymer, sodium EDTA, ammonium oxalate, Arquad). The precipitate is (1) stirred with filter aid, filtered, stirred with HC1, refiltered, mixed with 2-ethoxyethanol, filtered, washed, and the filtrates are combined, acidified with HC1, NaCl is added, and the crystals are collected, washed with 2-ethoxyethanol, water, and ethanol, and dried (67), or (2) extracted into methyl isobutyl ketone, the extracts are combined, filtered, and acidified with HC1, and the crystals are collected and washed with water, 2-ethoxyethanol, and isopropanol, and vacuum-dried. If the crystals are greenish, they are treated with sodium hydrosulfite at pH 1.8, filtered, washed, and dried as in (1) above (68). 

Complexing chelating) agents citric acid, tartaric acid, B sodium tartrate), kerosene, segesterene, sodium citrate, oxalic acid, sodium oxalate, or orthophosphoric acid X... 

The chelating agents used by researchers to enhance electrochemical remediation include EDTA, citric acid, oxalic acid, ammonia, iodide/iodine, potassium iodide solution, sodium chloride solution, l-hydroxyethane-l,l-diphosphonic acid (HEDPA), HPCD, and so on. EDTA is the most frequently used chelating agent in electrochemical remediation. The complexation chemistry of EDTA is briefly outlined as an illustration. 

EDTA (ethylenediaminetetraacetic acid) forms stable metal chelates with a number of metal ions. Using this reagent as a complexing- agent, arsenic, bismuth, and selenium can be determined without any interference in the presence of nickel and cobalt. The cobalt-EDTA chelate is stable in 5 M HCl solution, whereas the corresponding bismuth complex is not. The influence of copper on the determination of arsenic can also be eliminated with EDTA, but not in the determination of selenium. Thiourea has been used to eliminate the influence of copper in the determination of antimony and sodium oxalate to eliminate the influence of copper and nickel in the determination of tin. An addition of thiosemicarbazide and 1,10-phenanthro-line reduces the interference of copper, nickel, platinum, and palladium in the determination of arsenic. 

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