Synthesis of a Metal Ion Adsorbent from Banana Fibers and Its Adsorption Properties for Rare Metal Ions

The synthesis of metal ion adsorbents from modified banana fibers comprising a Schiff base was investigated. The adsorption properties of a metal ion adsorbent were evaluated, and banana fiber (BF)- g -(glycidyl methacrylate)(GMA)(BF-GMA) were synthesized. A Schiff base 2,2’-{iminobis[ethane-2,1-diylnitrilo(E)methylidine]}bisphenol was synthesized via a reaction of diethylenetriamine and 5-bromo-salicyialdehyde in methanol. A metal ion adsorbent (BF-GMA(Br)) was synthesized via a reaction of the Schiff base with BF-GMA. Over 90% of La 3+ , Gd 3+ , Tm 3+ , Pr 3+ , Tb 3+ , Yb 3+ , Nd 3+ , Dy 3+ , Lu 3+ , Sm 3+ , Ho 3+ , Eu 3+ , and Er 3+ were adsorbed in a pH range of 6.0–6.6 by the synthesized metal ion adsorbent. Almost 100% of In 3+ at a pH value of 3.0–4.0 and 95% of Ga 3+ at a pH value of 3.9 were absorbed, thereby showing the maximum adsorption percentage. Almost 15% and 25% of In 3+ was adsorbed at a pH value of 1.4–1.6 and 1.8, respectively. Adsorption of Ga 3+ was barely observed in the pH range of 1.4–1.8. These results show that banana fibers can be utilized as metal ion adsorbents.