| Abstrakt: |
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 [ABSTRACT FROM AUTHOR] |
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