The novel PEI-modified biochars and their application for the efficient elimination of Cr(VI) from aqueous solutions

Abstract

In this study, the polyethyleneimine (PEI) was grafted onto the biochars from chestnut shells and nori via the cross-linking reaction. Scanning electron microscopy, transmission electron microscopy and Fourier transferred infrared spectroscopy analysis indicated that the PEI was successfully grafted on the surface of biochars. The PEI modified and pristine biochars were used as adsorbents to remove Cr(VI) from aqueous solutions as a function of pH, ionic strength, contact time and initial concentrations of Cr(VI) through batch technique. The strongly pH-dependent and ionic strength-independent of Cr(VI) sorption indicated that the sorption was mainly dominated by electrostatic interaction and inner-sphere surface complexation. The maximum sorption capacities of PEI modified chestnut shell and nori biochars were 141.42 and 222.84 mg/g, respectively, which were significantly higher than those of pristine biochars. The PEI grafted onto the biochars significantly enhanced Cr(VI) sorption capacity because PEI, which contains volumes of amine/imine groups, provided an excellent platform for Cr(VI) ions removal. In addition, the sorption-desorption experimental results indicated that the PEI modified biochars possessed a stable and recyclable performance. All these results manifested that the PEI modified biochars could be applied as environmentally friendly and efficient adsorbents for the removal of Cr(VI) from wastewater.

Simultaneous removal of methyl orange and Cr(VI) using polyethyleneimine-modified corncob-derived carbon material

“…However, the greatly reduced BET surface area of PEI-CCM ( Fig. 3a) decreased the MO adsorption capacity of PEI-CCM (Lv et al 2018). Although the adsorption capacity for MO decreased by approximately 20% after the CCM was modified by the PEI, the Cr(VI) adsorption capacity of the PEI-CCM increased by more than nine times compared with the CCM, making the PEI-CCM a high-performance adsorbent for the adsorption of MO and Cr(VI).…”

“…To examine the reusability of the PEI-CCM adsorbent, an adsorption-desorption experiment was performed. The used PEI-CCM adsorbent was stirred in 1 M NaOH solution for 1 h to release the adsorbed chromium ions (Lv et al 2018). Then, the treated PEI-CCM adsorbent was washed using methanol to remove the MO.…”