Method for preparing lithium extraction absorbent and its application

A method for preparing a lithium extraction adsorbent, the method comprising:

• (i) forming a homogeneous casting liquid by stirring a metal-based lithium ion sieve, a chitosan, and a quaternized chitosan;
• (ii) adding the homogeneous casting liquid dropwise to a solidifying liquid to obtain gel particles, wherein the solidifying liquid consists of sodium hydroxide and ethanol;
• and
• (iii) washing the gel particles to neutrality with deionized water to obtain washed gel particles, followed by placing the washed gel particles in a glutaraldehyde solution for stirring to crosslink for 0.5 h to 12 h to obtain crosslinked gel particles, freeze-drying the crosslinked gel particles to obtain the lithium extraction adsorbent, activating the lithium extraction adsorbent by placing the lithium extraction adsorbent into an alkali activator for stirring for 0.5 h to 12 h, and washing the lithium extraction adsorbent to neutrality with deionized water to obtain an activated lithium extraction adsorbent, wherein the alkali activator includes one or more of sodium hydroxide, barium hydroxide, potassium hydroxide, and ammonia, a concentration of the alkali activator is in a range of 0.001 M to 1 M, and a time of activating is 0.5 h to 12 h.