Investigation on the adsorption properties of Cr(vi) ions on a novel graphene oxide (GO) based composite adsorbent

Abstract

In this study, we prepared polyethyleneimine (PEI) and graphene oxide (GO) composite adsorbent PEI-GO through an amidation reaction between the amine groups of the PEI and the carboxyl groups of the GO. Adsorption performance of the PEI-GO was tested by removing Cr(VI) ions from an aqueous solution. The physico-chemical properties of the GO, pristine and Cr(VI) ions loaded PEI-GO were investigated by the FT-IR, SEM-EDX and XPS methods. To investigate the adsorption kinetics of Cr(VI) ions onto this newly developed PEI-GO, we performed a batch of experiments under different adsorption conditions: content of the PEI in the PEI-GO, solution pH, initial Cr(VI) ion concentration, adsorption temperature and contact time. The prepared PEI-GO exhibited an encouraging uptake capacity of 539.53 mg/g. The adsorption process was fast, within the first 1 h, Cr(VI) ion adsorption onto the PEI-GO was about 71 %, and the adsorption equilibrium could be obtained within 14 h. Kinetics experiments indicated that the adsorption process could TP * P T 2 be described by the pseudo-second-order kinetic model. Furthermore, our adsorption equilibrium data fit the Langmuir isotherms well (R 2 >0.99). The removal mechanism of Cr(VI) ions from the solution consists of two steps: (1) Cr(VI) ions binds to the 4PEI-GO by the electrostatic interaction between the negatively charged Cr(VI) ions species and the protonated amine groups of the 4PEI-GO; and (2) small part of Cr(VI) ions were reduced to Cr(III) ions with the assistance of π electrons on the carbocyclic six-membered ring of the 4PEI-GO and then bind on the 4PEI-GO by the electrostatic attraction between Cr(III) ions and negatively charged groups (COO − ) of the 4PEI-GO. Based on the results obtained in this work, it can be concluded that the prepared PEI-GO can be an effective and potential adsorbent for removing Cr(VI) ions from an aqueous solution.

Highly effective removal of Cu(II) by triethylenetetramine-magnetic reduced graphene oxide composite

“…The appearance of a vibration band around 1661 cm −1 is ascribed to the C O stretching of the primary amide, and the disappearance of the carboxylic group bands at 1723 cm −1 of the pristine GO indicates the formation of amide linkages. The band at 1575 cm −1 is attributed to the stretching vibration of N-H (in the C-NH group) [44]. In addition, 577 cm −1 is the characteristic peak of Fe 3 O 4 [45].…”

Liquid crystal polaroid glass electrode from e-waste for synchronized removal/recovery of Cr +6 from wastewater by microbial fuel cell

“…S3). The binding energies obtained at 576.6 eV and 579.2 eV are in chromium 2p region and corresponding oxygen 1s region is obtained at 533.96 eV and 535.09 eV (Chen et al, 2014). From this analysis, the valence state of chromium can be attributed to Cr +3 .…”

Carbon nanotubes, graphene, and their derivatives for heavy metal removal

“…Chen et al [133] attached polyethyleneimine (PEI) to the GO through an amidation reaction between the amine groups of PEI and the carboxyl groups of GO, which could not only effectively prevent the agglomeration of GO nanosheets but also greatly enhance its adsorption performance for metal ions. The prepared PEI-GO composite showed a much higher maximum uptake capacity for Cr(VI) than many other conventional adsorbents, such as ethylenediamine-functionalized Fe 3 O 4 , PVP-modified activated carbon, mesoporous TiO 2 , polypyrrole/Fe 3 O 4 nanocomposite, hierarchical porous carbon, and chitosan-Fe(III) complex.…”