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Properties and Applications of Molybdenum
Published in C. K. Gupta, Extractive Metallurgy of Molybdenum, 2017
A solution of molybdic acid or an acid molybdate solution when treated with a reducing agent such as SO2, H2S, Zn, glucose, etc. takes on a deep blue color which is associated with the formation of the so-called molybdenum blue. It essentially occurs at an intermediate stage in the oxidation-reduction series, and for this reason it is easily overlooked if the reaction responsible for producing it is not under close control. With a solution which is too alkaline or too strongly acidic, the blue color does not appear at all. Molybdenum blue is a compound whose composition corresponds approximately to the formula Mo5O14∙xH2O (or according to other data Mo8O23∙xH2O). Molybdenum blue exists in a colloidal state in solution. It is readily adsorbed by surface active substances (e.g., by plant or animal tissues) to which it imparts a blue color.
Phosphorus
Published in Pradyot Patnaik, Handbook of Environmental Analysis, 2017
The principle of the colorimetric test is based on the reaction of orthophosphate with ammonium molybdate under acidic conditions to form a heteropoly acid, molybdophosphoric acid, which, in the presence of vanadium, forms yellow vanadomolybdophosphoric acid. The intensity of the color is proportional to the concentration of phosphate. Often, yellow is not a strong color to measure, especially, when the sample is dirty. Therefore, the molybdophosphoric acid formed may be reduced with stannous chloride to form molybdenum blue that has an intense color. The same dye may be formed by the reaction of orthophosphate with ammonium molybdate and potassium antimonyl tartrate in an acid medium and reduction with ascorbic acid or an amino acid.
Phosphorus Analyzer
Published in Béla G. Lipták, Analytical Instrumentation, 2018
The simplest colorimetric procedures are to determine soluble orthophosphate. In the commonly used aminonaphtholsulfonic acid method,1 ammonium molybdate reacts with a dilute phosphorus solution to produce molybdophosphoric acid, which is reduced to the intensely colored complex, molybdenum blue, by the combination of aminonaphtholsulfonic acid and sulfite reducing agents.
Synergistic effect of PANI–ZrO2 composite as antibacterial, anti-corrosion, and phosphate adsorbent material: synthesis, characterization and applications
Published in Environmental Technology, 2019
Frances Camille P. Masim, Cheng-Hsien Tsai, Yi-Feng Lin, Ming-Lai Fu, Minghua Liu, Fei Kang, Ya-Fen Wang
With regard to the phosphate removal efficiency studies, the influence of contact time was assessed by reacting 450 mL of 200 mg P/L phosphate solution with 600 mg ZrO2, PANI or PANI–ZrO2 under vigorous stirring for 24 h. Several milliliters of the solution was sampled at different time intervals between 0 and 24 h of adsorption (0, 0.5, 1, 2, 6, 12 and 24 h). The sample solution was then filtered using a 0.45 µm membrane filter and the filtrate was taken for analysis. Total phosphate analysis followed a standard procedure according to the molybdenum blue method with a detecting wavelength of 880 nm. The amount of phosphate removed and the percentage removal efficiency were calculated using the standard curve for high concentrations.
Fabrication of alumina decorated graphene oxide nanocomposite for efficient removal of aqueous phosphate
Published in Inorganic and Nano-Metal Chemistry, 2022
Ajit Das, Debasish Mondal, Bholanath Panda, Sourav Mondal
Where the initial phosphate concentration (mg/l) is C0; Ct is the phosphate concentration (mg/l) at time t; V is the volume of phosphate solution (l); m is the adsorbent mass (g). The concentration of phosphate ions in the solution was determined by the molybdenum blue method at 820 nm. The assurance of phosphates fixation in water depends on the development of heteropolyacid among phosphates and acidic molybdate and further decreased to phosphomolbydenum blue complex by ascorbic acid.[46]