Mechanism of selective gold adsorption on ion-imprinted chitosan resin modified by thiourea

Thiourea-modified chitosan-imprinted resin (IM-TUCS) and a corresponding nonimprinted resin (NIM-TUCS) were synthesized and characterized using adsorption experiments. The adsorption results showed that adsorption reached equilibrium within 4 h. The adsorption data were better fitted using the Langm...

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Bibliographic Details
Published in:Journal of hazardous materials 2021-08, Vol.415, p.125617-125617, Article 125617
Main Authors: Guo, Junkang, Fan, Xiaohu, Li, Yanping, Yu, Shenghui, Zhang, Yi, Wang, Lei, Ren, Xinhao
Format: Article
Language:English
Subjects:
Adsorption
Au(III)
Ion-imprinted polymers
Selectivity
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Summary:Thiourea-modified chitosan-imprinted resin (IM-TUCS) and a corresponding nonimprinted resin (NIM-TUCS) were synthesized and characterized using adsorption experiments. The adsorption results showed that adsorption reached equilibrium within 4 h. The adsorption data were better fitted using the Langmuir model (R2>0.99), and the gold adsorption capacities of IM-TUCS and NIM-TUCS were 933.2 and 373.7 mg·g−1, respectively. The IM-TUCS adsorbent was more suitable for gold than other coexisting anions and cations. The possible mechanism underlying Au(Ⅲ) adsorption on IM-TUCS was further investigated using X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction analyses. The protonation of the amino group on the resin under low pH conditions promoted Au(Ⅲ) adsorption; O, N and S in the C‒OH, C˭S and C-NH2 groups contained in the IM-TUCS coordinated with Au(III) ions. The cross-linking of the imprinted resin provided holes that could hold Au(III), thus the imprinted resin supported more Au(III). The adsorption capacity of the IM-TUCS for Au(III) was significantly higher than that of the NIM-TUCS, which is attributed to the cross-linking of the imprinted resin. Moreover, the IM-TUCS showed specific recognition capabilities for Au(III). After elution with the eluent, IM-TUCS was reused for four cycles with a gold recovery rate of approximately 93%, revealing its high potential economic value. [Display omitted] •A thiourea-modified chitosan-imprinted resin (IM-TUCS) was synthesized.•The IM-TUCS was more selective for gold than for other coexisting metal ions.•The cross-linking of the imprinted resin provided holes that could hold Au(Ⅲ).•IM-TUCS was reused for four cycles with a gold recovery rate of approximately 93%.
ISSN:0304-3894
1873-3336
DOI:10.1016/j.jhazmat.2021.125617