Adsorption of yttrium (Y3+) and concentration of rare earth elements from phosphogypsum using chitin and chitin aerogel

Chitin powder and chitin-aerogel were prepared from shrimp wastes and used to uptake Y3+ from aqueous solutions and concentrate this rare earth element from phosphogypsum (PG). Chitin aerogel displays a specific surface area of 945 m2/g, while chitin powder is 3.6 m2/g, which largely influences its adsorption ability. Regarding the adsorption in synthetic solutions, the effect of pH on Y3+ removal is strong for chitin powder adsorbent. In contrast, no big pH influence was detected for chitin aerogel. Electrostatic interactions and chelation can highlight the proposed mechanism of Y3+ on chitin adsorbents for the powder and aerogel. Furthermore, in addition to these interactions, pore filling/pore diffusion is the main mechanism of Y3+ removal in the chitin aerogel. Chitin aerogel is efficient in concentrating 8 times the Y3+ from PG, a very complex matrix. The complex chitin aerogel-Y3+ can be a secondary source of rare earth elements for other applications.