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Lithium Adsorption on TiO2 Ion-sieve from Magnesium Treated Brine Sources

Naji Toosi, Alireza | 2015

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 48053 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Asgari, Masoud
  7. Abstract:
  8. Brines are one of the main resources for lithium extraction and Iran has got many high magnesium and low lithium brine resources. In order to extract lithium, it is required to carefully identify these resources and their associated compounds and then an appropriate method can be adopted to extract lithium. Among the Previous researches, Bahadori, Jandaghi and Moazeni developed methods for removal of undesirable brines elements, Deposition of lithium from refined brine and lithium adsorption anatase ion-sieves membrane respectively; in this study it has been tried to investigate the optimization of the adsorption process, onto the TiO2-B ion sieve with nanotube morphology. TiO2-B nanotubes were synthesized using hydrothermal method in NaOH solution. Nano titanate spinals were synthesized utilizing a second hydrothermal process in LiOH solution. Finally acid washing was carried out for lithium desorption from the resulting structure of the previous stage in order to obtain lithium. Nano ion-sieves derived from the abovementioned method were exposed to a synthetic medium containing specified amount of lithium ions to achieve an optimal condition of adsorption by adjusting the solution pH, adsorption time, acid washing concentration and acid washing time. Then, The optimal condition obtained then was used for the real brine which was initially refined from Calcium, Bore and Magnesium by using dilute H2SO4, contacting with Prolite 108 ion-exchange resin and adding a combination of NaOH and LiOH respectively. Characterization of the nanotubes was carried out using X-ray diffraction (XRD), scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and Brunauer–Emmett–Teller (BET). The optimized condition was adopted at the solution pH of 12, adsorption time of 48 hours, acid washing concentration of 0.1M and acid washing time of 28 hours which resulted in maximum lithium adsorption percentage of 96.2% for the synthetic medium and 80% for the brine contacting average amount of 80 and 50 ppm lithium ions in solution respectively. Adsorption measurements were carried out by atomic adsorption spectroscopy (AAS). Maximum capacity obtained from the experiments was about 18 mgs per gram of Nano absorbent. The result were appropriately fitted to the freundlich. Adsorption model and kinetic investigation revealed pseudo-second order kinetics shoving chemisorption adsorption
  9. Keywords:
  10. Lithium Extraction ; Absorption ; Ion Exchange ; Brine ; Titanium Oxide Beta Nanotube

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