Molybdenum species in acid solution

Jenkins, Iredell; Wain, A.G.

doi:10.1002/jbt.2570131206

Cited by 2 publications

(1 citation statement)

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“…Molybdenum and tungsten ions have several ionic forms in aqueous solution and these species are governed by the pH of the solution; the predominant species in highly acidic nitric acid solution for the Mo(VI) and W(VI) species is MoO 2 2+ and WO 3 , respectively 36–38 . On the other hand, the ionic forms of molybdate and tungstate ions in low acidic medium were H 2 MoO 4 and H 2 WO 4 35,39 .…”

Section: Resultsmentioning

confidence: 99%

Sorption behavior of tungsten and molybdenum on TVEX‐TOPO resin from nitric acid solution

Masry

Daoud

2021

J of Chemical Tech & Biotech

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BACKGROUND TVEX‐TOPO, which is a commercial low‐cost macroporous copolymer resin containing 50% (w% Extractant fraction of total adsorbent mass) trioctylphosphine oxide (TOPO) was used for solid–liquid extraction of tungsten(VI) (W(VI)) and molybdenum(VI) (Mo(VI)) from nitric acid solution. The different parameters affecting the sorption process of both metal ions such as contact time, [HNO3], initial concentrations, V/m ratio and temperature were separately studied. RESULTS The maximum sorption capacity of TVEX‐ TOPO resin was found to be 17.6 mg g−1 Mo(VI) and 10.7 mg g−1 W(VI) after five sorption stages. Thermodynamic parameters ∆H, ∆G, ∆S were found to be −51.7, −4.3 kJ mol−1 and 157 J mol−1 K−1 for Mo(VI) and −27.4, 1 kJ mol−1 and −93 J mol−1 K−1 for W(VI), respectively. The maximum desorption of W(VI) and Mo(VI) of 97.5% was achieved by reductive stripping with 2% and 4% ascorbic acid, respectively. The highest separation coefficient SMo/W was found to be 13.5 and 10 at V/m = 100 and [HNO3] = 0.1 mol L–1. The W(VI)/TVEX‐TOPO system was found to obey the Langmuir isotherm model with regression factor R2 = 0.999 and qm = 10.5 mg g−1, which is close to the maximum sorption capacity, which equals 10.7 mg g−1. Adsorption kinetics results indicated that the pseudo‐first‐order model is more applicable to W(VI) as qe(exp.) = 4.2 mg g−1 is close to qe(cal.) = 4.3 mg g−1, but Mo(VI) was found to fit with the pseudo‐second order‐model. CONCLUSION Recovery of Mo(VI) and W(VI) was applied to dental metal filaments waste of (Co‐Cr‐Mo) alloys using TVEX‐TOPO and a flow sheet describing the proposed process was given. © 2021 Society of Chemical Industry

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Section: Resultsmentioning

confidence: 99%