| Autor: |
Olayiwola, Afolabi Uthmon, Du, Hao, Wang, Shao-Na, Liu, Biao, Lv, Ye-Qing, Pan, Bo |
| Zdroj: |
Tungsten; 20220101, Issue: Preprints p1-15, 15p |
| Abstrakt: |
The production of ammonium paratungstate (APT) is riddled with the generation of wastewater, which causes environmental problems. To solve the problem of wastewater generation at source, a membrane electrolysis-NH3⋅H2O precipitation method, which prevents wastewater generation and recycles the reagents used in the process, was proposed and investigated in this study. The electrolysis process was investigated based on parameters such as initial cathodic and anodic NaOH concentrations, and current density. The results showed that an increase in current density and initial cathodic NaOH concentration and a decrease in the initial anodic NaOH concentration would enhance the separation of tungsten and sodium. The optimum condition was found at a current density of 666 A•m−2, initial anodic and cathodic NaOH concentrations of 69 g• L−1and 40 g• L−1, with a current efficiency of 75.40%, and energy consumption for producing 1 ton of NaOH was 2184 kW• h. The precipitation process was investigated based on the acidic high W/Na molar ratio solution obtained by the electrolysis process with NH3⋅H2O as the precipitant. Parameters such as excessive coefficient, temperature, and W/Na molar ratio were studied. The result showed that the variation of excessive coefficient and solution temperature had an opposite effect on the purity of the APT, while an increase in the W/Na molar ratio would increase the product purity. The precipitation product obtained had a purity of 99.6% and was characterized using X-ray diffraction, inductively coupled plasma, and scanning electron microscopy. The methods proposed in this study could provide fundamental information for the design of a cleaner APT production process. |
| Databáze: |
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