Molybdenum complexes citric acid

Add to the sample solution (containing 1 -25 g of Mo) 4 mL of 1 3 sulphuric acid, 3 drops of 85 per cent phosphoric(V) acid, and 0.5 g of citric acid. Dilute with water to 20 mL and add 2 mL of dithiol solution. Allow to stand at room temperature for 2 hours. Extract the molybdenum complex with 13 mL and 10 mL portions respectively of re-distilled butyl acetate, and make up to 25.0 mL with this solvent in a graduated flask filter through glass wool if not entirely clear. Determine the absorbance of the solution at 670 nm. Prepare a calibration curve as detailed in Section 6.14. 

Molybdenum(VI) complexes citric acid, 476 IR spectra, 469 guanidine, 283 hydroxamic adds, 506 maleic add, 475 conformation, 467 crystal structure, 476 tartaric add, 479 NMR, 468... 

Spec A = 580 nm of Hg(II)/xylenol orange complex display a sharp hypochromic effect upon substituting amine buffers with a citric acid-phosphate (pH = 7.5) Sequential injection analysis to the determination of CPC based on the sensitized molybdenum-bromopyrogallol red reaction... 

They were studied in the context of chemical processes occurring in soils and aquatic systems, but also considering their importance in other circumstances. Citric acid as a complexing agent is often used in the separation of actinides, lanthanides and other toxic metals from wastes, sediments and contaminated soils. Citric complexes of molybdenum and other metals are components of electrolytic baths used for electrodeposition and cleaning of corrosion resistant alloys. 

Samotus A, Kanas A, Dudek M, Grybos R, Hodorowicz E (1991) 1 1 Molybdenum(VI) citric acid complexes. Transit Met Chem 16 495 99... 

Hamada YZ, Bayakly N, George D, Greer T (2008) Speciation of molybdenum(VI)-citric acid complexes in aqueous solutions. Synth React Inorg Metal-Org Nano-Metal Chem 38 664-668... 

Zhou ZH, Wan HL, Tsai KR (1997) Molybdenum(VI) complex with citric acid synthesis and structural characterization of 1 1 ratio citro molybdate K2Na [(Mo2)20(Cit)2] 5H2O. Polyhedron 16 75-79... 

Induced co-deposition is observed for deposition of metals that cannot be deposited at all from an aqueous solution, such as W, or can barely be deposited, with a low current efficiency and poor adherence of the deposit, such as Re. However, alloys of W with the iron-group metals can readily be formed, using, for example, a solution of NiS04 and Na2W04, with citric acid added as a complexing agent. In this particular case it was shown that a Ni-W alloy is deposited from a complex containing both metals, while Ni is also deposited in parallel reactions from its complex with citrate. Very similar behavior is observed for deposition of alloys of molybdenum. 

Interference by phosphate ion is an especially common problem. Since the phosphate ion reacts like silica to form a yellow phosphomolybdic acid, its interference must be eliminated. Numerous techniques have been proposed, either for separating the silica and phosphorus before analysis or preferentially reducing silicomolybdic acid to molybdenum blue in the presence of the phosphomolybdic acid (311-313). Snell and Snell (314) summarized the possible procedures (a) precipitating and removing phosphate as the calcium salt. (6) adjusting pH so only silica will form the yellow color, (c) destroying the yellow phosphate complex with citric, oxalic, or tartaric acids, and d) preferentially reducing the silicomolybdic acid to molybdenum blue. 

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