Capture-reduction mechanism for promoting Cr(VI) removal by sulfidated microscale zerovalent iron/sulfur-doped graphene-like biochar composite

Abstract

The application of microscale zerovalent iron (mZVI) in the removal of Cr(VI) from water is plagued with the readily formation of oxide passivation layer. In this study, we propose a “capture-reduction” mechanism to enhance the Cr(VI) removal performance of mZVI under anaerobic condition through dual modification, i.e., sulfidation and construction of composite with sulfur-doped graphene like biochar (SGB). The S-mZVI/SGB has a Cr(VI) removal capacity of 70.2 mg·g− 1 at circumneutral pH, which is 56 times of that of mZVI. The 1,10-phenanthroline shielding experiments indicate that the contribution of Fe(II) to Cr(VI) removal is only 17.6%. Density-theory-functional (DFT) calculation results indicate that sulfur doping could significantly promote the adsorption of Cr(VI) on SGB nanosheets. The mechanism study confirmed the “capture-reduction” Cr(VI) removal mechanism, whereby the SGB nanosheets capture Cr(VI) ions and receive electrons from Fe0 to reduce Cr(VI) to Cr(III). Considering its advantages such as low cost and easy preparation, the S-mZVI/SGB composite is a promising green material for the removal of Cr(VI) from water. Graphical Abstract

Synthesis of Integrated Material with Activation and Oxidation Functions by Mechanical Milling of Activated Carbon and Persulfate for Enhanced Tetracycline Degradation over Non-Radical Mechanism

“…The appearance of S-O-C verifies that AC and PS are successfully bonded under mechanical action, indicating these two materials have been closely combined to form a stable composite material during the milling process. The broad band at 3429 cm −1 corresponds to the stretching vibration of −OH [42,43]. This peak in MAC and M(AC-PS) is slightly stronger than that in AC, and almost disappears in M(AC-PS)-after reaction.…”

Hydrothermal Carbonization Technology for Wastewater Treatment under the “Dual Carbon” Goals: Current Status, Trends, and Challenges

“…It not only transforms waste into valuable resources but also reduces environmental pollution. The carbon materials produced take the advantages of low cost, excellent chemical stability, large surface area and abundant pores [34].…”

Coprecipitation of Fe/Cr Hydroxides at Organic–Water Interfaces: Functional Group Richness and (De)protonation Control Amounts and Compositions of Coprecipitates

“…3 For the development of an efficient Cr detoxication strategy, iron(0/II)-based materials have been used for Cr(VI) reduction and concurrent Fe(III)/Cr(III) coprecipitation in both Cr contaminated soils and industrial Cr(VI) wastewater treatment. 4,5 During metal/Fe hydroxide coprecipitation, metals (e.g., Cr, Al, etc.) can be sequestered in Fe hydroxides through structural incorporation, surface adsorption, and surface precipitation.…”

“…The Cr released into the environment through both natural and anthropogenic activities poses great health risks to plants, animals, and humans. , Compared with Cr­(III), Cr­(VI) is appreciably more toxic and mobile . For the development of an efficient Cr detoxication strategy, iron­(0/II)-based materials have been used for Cr­(VI) reduction and concurrent Fe­(III)/Cr­(III) coprecipitation in both Cr contaminated soils and industrial Cr­(VI) wastewater treatment. , During metal/Fe hydroxide coprecipitation, metals (e.g., Cr, Al, etc.) can be sequestered in Fe hydroxides through structural incorporation, surface adsorption, and surface precipitation .…”