Chitosan derived layered porous carbon and its performance on gallium adsorption

Abstract

BACKGROUND Gallium (Ga) is widely used in the preparation of low‐melting alloys and is also mainly used in electronics. However, Ga is a rare‐scattered element that has no independent ore deposits. Fortunately, adsorbents with high specific surface area have shown great potential for the recovery and enrichment of Ga from mineral industry wastes or recycled electronics. Consequently, porous carbons with hierarchical layered structures were prepared as adsorbent for the recovery of Ga. Besides the routine hydrothermal and carbonizing treatments, chitosan (CS) derivatives were further activated by potassium hydroxide, zinc chloride, and ferric trichloride to improve their respective specific surface areas. RESULTS Nitrogen adsorption analysis showed that the porous carbon activated by KOH at 800 °C (CS‐800) had the highest specific surface area (2997 m2 g−1). The maximum adsorption capacity for Ga(III) was 129.83 mg g−1, which is better than that of other well‐known carbon based adsorbents. CS‐800 also exhibited good selectivity for Ga(III) among various competitive ions, such as Zn(II), Cu(II), Ge(IV), and Al(III). In addition, the adsorbent showed good reusability; the recovery percentage of Ga(III) remained above 90% after six adsorption‐elution experiments. CONCLUSION KOH is an ideal activating agent to increase the surface area of porous carbon and 800 °C is its optimal temperature. This agent can provide sufficient active surface sites for metal ions adsorption. This work provides a strategy for the regulation of CS derived porous carbon and is expected to play a key role in real applications for the recovery of Ga. © 2023 Society of Chemical Industry (SCI).

Preparation of 4-Amino-3-hydrazino-1,2,4-triazol-5-thiol-Modified Graphene Oxide and Its Greatly Enhanced Selective Adsorption of Gallium in Aqueous Solution

“…However, the adsorption selectivity of these chelating adsorbents needs to be improved because the interactions between the carboxyl groups and other coexisting metal ions cannot be ignored. In comparison, chitosan (CS)-derived porous carbon that was further activated by KOH at 800 °C (CS-800) exhibited good adsorption selectivity for Ga 3+ rather than for other metal ions such as Zn 2+ , Cu 2+ , Ge 4+ and Al 3+ [ 12 ]. Although the detailed adsorption mechanism was not further discussed by the authors, we propose that the nitrogen (N)-containing functional groups might contribute to the adsorption.…”

Assessment of Two Materials as Adsorbents for the Effective Removal and Further Pre-Concentration of Gallium from Aqueous Solutions: Mesoporous Carbon vs. Clinoptilolite

“…More recently, Gao et al [28,29] employed a persimmon-based ion imprinted polymer as gallium adsorbent, achieving 80% of gallium removal. On the other hand, Cui et al [30] employed chitosan-derived layered porous carbons as adsorbents, reaching gallium removals of up to 90%, and Wang et al [31] employed a chitosan-based ion imprinted polymer, reaching gallium removals of up to 80%. Finally, Meng et al [32] employed a porous resin composed of 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (P507) and tributyl phosphate (TBP) attached to a silica matrix, as adsorbent with a large capacity to remove gallium.…”