Facile Synthesis of Magnetic Biochar Derived from Burley Tobacco Stems towards Enhanced Cr(VI) Removal: Performance and Mechanism

Abstract

In this study, ferric-loaded magnetic burley tobacco stem biochar (MBTS) was synthesized via pyrolysis to improve the removal of Cr (VI). The results showed that MBTS had an adsorption capacity of 54.92 mg Cr (VI)/g, which was about 14 times higher than raw burley tobacco stem biochar (i.e., 3.84 mg/g). According to the findings obtained, a three-step mechanism of Cr (VI) removal by MBTS was further put forward, i.e., (1) Cr (VI) exchanged with hydroxyl groups on MBTS, (2) the reduction in Cr (VI) to Cr (III) mediated by oxygen-containing groups, and (3) the chelation of produced Cr (III) with the amino groups on MBTS. FTIR spectra further revealed that C-N, C-H, and C=C groups played an important role in Cr (VI) removal. Furthermore, the adsorption equilibrium and kinetics of Cr (VI) on MBTS could better be described by the Langmuir equation and pseudo-second-order rate equation. This study clearly demonstrated that ferric-loaded biochar derived from burley tobacco stems could serve as a cost-effective magnetic adsorbent for the high-efficiency removal of soluble Cr (VI) from wastewater. Tobacco stem-adsorbed Cr (VI) realized a green path for treating waste by waste.

Synthesis of a Novel Adsorbent Based on Chitosan Magnetite Nanoparticles for the High Sorption of Cr (VI) Ions: A Study of Photocatalysis and Recovery on Tannery Effluents

“…Scheme 1 shows the expected binding mechanism of the chromate from the acidic medium during treatment with MC-TDPD sorbent, which indicates the exchange with hydroxyl groups, expected reduction of Cr(VI) by the effect of organic to Cr(III), and chelation reaction with amine groups. This is parallel with the results obtained by Cui et al [77], who also suggest the reduction mechanism as follows from Equations ( 1)-( 4).…”

Structural Properties of Graphene Oxide Prepared from Graphite by Three Different Methods and the Effect on Removal of Cr(VI) from Aqueous Solution

“…Typically, the binding energies of Cr 2p 3/2 at ~578 eV and Cr 2p 1/2 at ~588 eV refer to Cr(III), while the binding energies of Cr 2p 3/2 at ~582.5 eV and Cr 2p 1/2 at ~591.5 eV correspond to Cr(VI). This phenomenon implies that both Cr(VI) and Cr(III) are present on the surface of GO-M3, which is mainly due to the fact that Cr(VI) is immobilized on the surface of GO-M3 by adsorption, and a large portion of Cr(VI) that is anchored on the surface of GO-M3 reacts with a large number of oxygen-containing functional groups on the surface of GO-M3 by redox reaction, thus generating a large amount of Cr(III) [ 55 , 56 , 57 ].…”

Heavy metal pollution in the aquatic environment: efficient and low-cost removal approaches to eliminate their toxicity: a review

“…138–140 Many studies have attempted to develop magnetic-modified biochar to enhance the separation efficiency of biochar particles after the wastewater treatment process. 141–145…”

“…[138][139][140] Many studies have attempted to develop magnetic-modied biochar to enhance the separation efficiency of biochar particles aer the wastewater treatment process. [141][142][143][144][145] One of the challenges in using adsorption-based treatment is its poor selectivity for heavy metals in complex wastewater matrices. The presence of other competing ions, organic matter, or pH uctuations can affect the adsorption performance of biochar.…”