| As the metallic lithium and its compounds have been widely applied in chemical industry, new energy and many other fields, demand for lithium products in the international market continues to grow. In our country, there is abundant of salt lake brine lithium resources, in which the content of Li+ is low while content of Mg2+ is high. Therefore, traditional methods, such as precipitation and calcination process, are not suitable for extracting lithium from this kind of salt lake brine due to high costs. Adsorption method is recognized as the most economical and environmentally friendly way to extract lithium from brine that the ratio of magnesium lithium is high. It becomes the main trend of extracting lithium from brine.Now manganese lithium ion sieve and titanium lithium ion sieve are mainly researched in worldwide. As the dissolved loss rate of manganese lithium ion sieve in pickling process is high, generally up to 2%～5%, thus limits its application in industry. Titanium lithium ion sieve has the advantages of large adsorption capacity, stable structure under acidic conditions and good cycle performance, so it became the research hotspot in recent years. Currently, titanium lithium ion sieve is mainly for extracting lithium from low lithium brine. Its equilibrium adsorption time is long and dissolved loss rate of titanium is 0.17%～4.2%. In our country, the content of Li+ in the mother liquor of salt lake and underground brine after extracting sodium and potassium is high, generally up to3.0～5.0g/L. So there is a certain gap between industrial applications.Under auspices of the national "863" project, aimed at the current issues of high dissolved loss rate and long adsorptive time for the titanium lithium adsorbent, high exchange capacity and short adsorptive time while low dissolved loss rate of lithium adsorbent H2TiO3 was obtained from the acid-modified adsorbent precursor Li2TiO3 by sol-gel method in this paper. The experiment was characterized by TG/DTG, XRD, SEM and chemical analysis. The results indicate that single-phase of Li2TiO3 was obtained by calcining the dry gel at 750℃ in air for 18h when the lithium titanium ratio is 2.2, lithium adsorbent was prepared via acid treatment. The extraction rate of Li+ is 98.68% and the dissolved loss rate of Ti4+ is 0.06% in pickling process.Saturated adsorption capacity of the adsorbent for Li+ is 39.15mg/g in strong alkaline solution under the condition of adsorptive time is 120 minutes,which concentration of Li+ is 5.0g/L. The selectivity sequence for main metal ions in the brine is:Li+>Na+>K+>Mg2+, 1,αNa Li and αM8 Li are 56.35、52.75、64.44 respectively. After 6 cycles,the operating adsorption capacity maintains at about 18.62mg/g,lithium desorption rate maintains at 99.53%,and dissolved loss rate of titanium is less than 0.02% in single cycle process.Compared with the existing synthesis technology of lithium ion sieve, synthesis temperature of this lithium adsorbent is lower, equilibrium adsorption time reduces nearly 100 times and dissolved loss rate of titanium reduces nearly 10 times. In addition,the adsorbent has good adsorption properties in low concentration or high concentration solution of lithium ion, especially suitable for extracting lithium from high concentration solution of lithium ion, therefore it has certain industrial application value. |
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