Adsorption Separation of Cr(VI) from a Water Phase Using Multiwalled Carbon Nanotube-Immobilized Ionic Liquids

Lihan Sun; Mengru Wang; Wei Li; Sha Luo; Yan Wu; Chunhui Ma; Shouxin Liu

doi:10.1021/acsomega.0c02016

Adsorption Separation of Cr(VI) from a Water Phase Using Multiwalled Carbon Nanotube-Immobilized Ionic Liquids

ACS Omega. 2020 Sep 1;5(36):22827-22839. doi: 10.1021/acsomega.0c02016. eCollection 2020 Sep 15.

Authors

Lihan Sun¹, Mengru Wang¹, Wei Li¹, Sha Luo¹, Yan Wu¹, Chunhui Ma¹, Shouxin Liu¹

Affiliation

¹ Key Laboratory of Bio-based Material Science and Technology (Ministry of Education), College of Material Science and Engineering, Northeast Forestry University, 150040 Harbin, China.

Abstract

Three types of multiwalled carbon nanotubes (MWCNTs, MWCNTs-OH, and MWCNTs-COOH) were used as carriers and five types of ionic liquids (ILs) were immobilized on each carrier by an impregnation method. Boehm titration, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, specific surface area analysis by the Brunauer-Emmett-Teller method, and thermogravimetric analysis were performed to investigate [C4mim]HSO₄ adsorption by the MWCNTs. The MWCNT-immobilized IL was used for Cr(VI) removal from a water phase. The adsorption properties of MWCNTs-COOH-immobilized [C4mim]HSO₄ were investigated by single-factor analysis. The results showed that the Cr(VI) removal rate was 52.14% and the adsorption capacity was 31.29 mg/g. The optimum adsorption conditions were as follows: initial Cr(VI) concentration, 60 mg/L; adsorbent dosage, 50 mg; pH 2.0; adsorption temperature 40 °C; and adsorption time, 200 min. Adsorption isotherm data fitted the Freundlich model, which indicates that the adsorption process was in line with the multimolecular layer adsorption theory. The Cr(VI) adsorption behaviors of the three adsorbents were consistent with a pseudo-second-order dynamic model. Thermodynamic analysis of the reaction systems was also performed. The Cr(VI) removal rates of MWCNTs-3, MWCNTs-OH-3, and MWCNTs-COOH-3 were 27.97, 9.39, and 7.34% lower than the initial removal rates after five cycles.