title: A novel adsorbent TEMPO-mediated oxidized cellulose nanofibrils modified with PEI: Preparation, characterization, and application for Cu(II) removal.
abstract: This study describes the preparation of a novel adsorbent based on cellulose nanofibrils by first TEMPO mediated oxidation and then PEI grafting (TOCN-PEI) for heavy metal removal. FTIR results demonstrated the successful introduction of the adsorption functional groups (carboxyl and amino groups), and the elemental analysis and acid base titration were used to quantify the contents of these introduced groups. The kinetics curve suited the pseudo-second-order model better and the equilibrium data well fitted the Langmuir model, with the maximum Cu(II) uptake of 52.32mgg(-1). Kinetic study showed that the PEI grafting increased the initial adsorption rate of the TOCN-PEI compared with the adsorbents without PEI. Thermodynamic study was carried out through isothermal titration calorimetry (ITC) measurement and the binding reaction was found to be exothermic and driven by enthalpy change. The adsorption process by TOCN-PEI was pH dependent, and decreasing pH would lead to desorption of Cu(II) ions, thus make the reuse of the absorbent more convenient through adsorption-desorption cycles.
authors.affiliation: CAS Key Laboratory of Urban Pollutant Conversion, Department of Chemistry, University of Science and Technology of China, Hefei 230026, China.
authors.forename: Nan
authors.initials: N
authors.lastname: Zhang
authors.affiliation: CAS Key Laboratory of Urban Pollutant Conversion, Department of Chemistry, University of Science and Technology of China, Hefei 230026, China.
authors.forename: Guo-Long
authors.initials: GL
authors.lastname: Zang
authors.affiliation: CAS Key Laboratory of Urban Pollutant Conversion, Department of Chemistry, University of Science and Technology of China, Hefei 230026, China.
authors.forename: Chen
authors.initials: C
authors.lastname: Shi
authors.affiliation: CAS Key Laboratory of Urban Pollutant Conversion, Department of Chemistry, University of Science and Technology of China, Hefei 230026, China.
authors.forename: Han-Qing
authors.initials: HQ
authors.lastname: Yu
authors.affiliation: CAS Key Laboratory of Urban Pollutant Conversion, Department of Chemistry, University of Science and Technology of China, Hefei 230026, China. Electronic address: gpsheng@ustc.edu.cn.
authors.forename: Guo-Ping
authors.initials: GP
authors.lastname: Sheng
keywords: Cu(II); Isothermal titration calorimetry (ITC); Langmuir adsorption isotherm; Polyethylenimine (PEI) modification; TEMPO oxidized cellulose nanofibrils