Selective separation of tungsten from the model and industrial effluents through supported liquid membrane
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ORIGINAL PAPER
Selective separation of tungsten from the model and industrial effluents through supported liquid membrane Nauman Ali1 · Sameera Shah1 · Adnan Khan1 · Sher Bahadar Khan3 · Tahseen Kamal3 · Abdullah M. Asiri2,3 Received: 17 April 2020 / Accepted: 10 August 2020 © Institute of Chemistry, Slovak Academy of Sciences 2020
Abstract In this study, a selective separation of tungsten W (VI) from a mixed salt solution was done through a liquid-membrane technology. The transport of W (VI) across the supported liquid membrane was also applied on real sample. Tertiary amine (Tri-n-dodecylamine) was used as an organic carrier and a supported liquid membrane of polypropylene separator (celgard 2400) was used in this experimental work. The selective separation of W (VI) was optimized by various parameters i.e., concentration of metal in feed, concentartion of stripping agent, type of stripping reagents, carrier concentration and pH effect. The extraction of W(VI) was maximized by the concentration of carrier up to 0.2 mol/dm3 diluted in n-hexane. The optimum concentration of sodium hydroxide was 0.2 mol/dm3 in the strip phase. The transport of tungsten increases by the increase of the pH of feed solution to basic from acidic up to the pH 8. At pH 8 in the feed phase, tri-n-dodecylamine efficiently extracted W (VI) from feed through anion exchange mechanism. The time duration for the transport of tungsten was 6 h at room temperature. The optimized reaction of W(VI) for the selective separation was applied on the scheelite ore with 93% recoved. The single membrane was used in all experiments, which confirmed the durability and stability of polypropylene membrane. Keywords SLM · Tungsten · Complex · Separation
Introduction In the recent past, the uses of heavy metals increased extensively on industrial scale for various purposes (Khan et al. 2016; Ali et al. 2018a, b). The proper disposal of their waste requires appropriate measures, as these wastes also contain valuable metals and dumping of these heavy metals is unwise due to the depletion of their primary resources and environmental hazard produced by these metals. Tungsten has the highest melting point and due to this reason, it is widely used for the high-pressure work, such as in super alloy for intense temperature work, as an electro-catalyst, in * Nauman Ali [email protected] 1
Institute of Chemical Sciences, University of Peshawar, Peshawar, Pakistan
2
Center of Excellence for Advanced Materials Research, King Abdulaziz University, P.O. Box 80203, Jeddah 2159, Saudi Arabia
3
Department of Chemistry, King Abdulaziz University, P.O. Box 80203, Jeddah 21589, Saudi Arabia
fertilizers and to control the oxygen and nitrogen compounds in power plants for controlling the pollution problems (Huo et al. 2014; Chen et al. 2016; Chong et al. 2016; Ravi et al. 2016; Stanciu et al. 2016). The long-term exposure to tungsten is carcinogenic (Medici et al. 2015) and at the same time, it is a valuable metal. It is usually found in combined form with other
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