A novel graphene oxide-dicationic ionic liquid composite for Cr(VI) adsorption from aqueous solutions

• Published in: Journal of hazardous materials 2021-08, Vol.416, p.125706-125706, Article 125706
• Main Authors: Shang, Jun, Guo, Yanni, He, Deliang, Qu, Wei, Tang, Yining, Zhou, Lei, Zhu, Rilong
• Format: Article
• Language: English
• Subjects: Adsorption; Cr(VI); Dicationic ionic liquid; Graphene oxide; Imidazole
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2021.125706

A novel graphene oxide-dicationic ionic liquid composite (GO-DIL) was prepared by modifying graphene oxide (GO) with a dicationic ionic liquid (DIL), 3,3′-(butane-1,4-diyl) bis (1-methyl-1H-imidazol-3-ium) chloride ([C4(MIM)2]Cl2). GO and GO-DIL were characterized by SEM, BET, FTIR, and XPS, and the materials were used for Cr(VI) adsorption. Batch adsorption studies showed that adsorption reached equilibrium within 40 min, and the optimal pH was 3, where the electrostatic attraction between GO-DIL and Cr(VI) was maximized. The maximum theoretical Cr(VI) adsorption capacity (qm) was 271.08 mg g−1, and qm remained above 228.00 mg g−1 after five cycles. The adsorption data were fitted well by both the pseudo-first-order kinetic model and the Langmuir model. Furthermore, thermodynamics calculations revealed that adsorption was a spontaneous endothermic process. Importantly, electrostatic attraction between Cr(VI) and the protonated imidazole N+ of GO-DIL played a critical role in Cr(VI) adsorption, and Cr(VI) was reduced to Cr(III). Thus, GO-DIL is predicted to be an effective adsorbent for Cr(VI) and other heavy metal ions in wastewater. [Display omitted] •A facile route to synthesize GO-DIL as novel adsorbents was provided.•Rate constant and adsorption capacity of Cr(VI) were greatly improved by DIL.•The adsorption of Cr(VI) on GO-DIL mainly depends on the protonated imidazole N+.•GO-DIL can be easily regenerated and reused for multiple cycles.