N-doped biochar-catalyzed dechlorination of carbon tetrachloride in sulfide-containing aqueous solutions: Performances, mechanisms and pathways

Ding, Longzhen; Wang, Yuhan; Tong, Lizhi; Liu, Na; Wang, Chao; Hu, Qing

doi:10.1016/j.watres.2022.119006

Cited by 23 publications

(21 citation statements)

References 49 publications

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“…In contrast, a previous study reported that TCCl 3 rather than TCCl 2 was detected in free radicals trapping experiments when the reaction was mediated by nitrogen-doped biochar, indicating the predominant formation of CHCl 3 . 22 This contradiction may be caused by two properties of the biochar: the much lower microporosity (as also reflected by the low micropore volume of Biochar; see Table S2) and the much higher pore hydrophilicity due to the larger pore sizes and more oxygen-and nitrogen-containing functional groups as compared to AC. Correspondingly, the newly formed •CCl 3 would be readily transformed to CHCl 3 through hydrogenolysis or reduction by accepting one electron and one proton (which is originally hydrated).…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…Previous studies have proposed several mechanisms to explain CM-facilitated reductive dechlorination of chlorinated compounds by sulfide in aqueous solutions, including enhanced electron transfer by graphitic carbon/nitrogen and/or surface quinone moieties, , reaction with more reactive soluble sulfur species (polysulfides and polysulfide free radicals) induced by surface oxygen functional groups or C–S–S– species formed at the surface of N-doped CMs, ,, and catalyzed reaction by surface active sites (e.g., zigzag carbons of graphenes) . Reaction with soluble and surface reactive sulfur species can be ruled out as major mechanisms because only slight fractions (9.7 and 2.7%) of CCl 4 were reduced by the Supernatant and Residue collected after prereacting sulfide with AC followed by separation with filtration (Figure S3).…”

Section: Resultsmentioning

confidence: 99%

“…32,34 For sulfideinduced reactions, the CCl 4 molecule can undergo nucleophilic substitution with sulfide or newborn reactive sulfur species to generate CS 2 or reduction to generate •CCl 3 that can further be transformed to CHCl 3 or react with sulfide to form CS 2 . 22,25 The low production of CO and its hydrated product HCOOH observed in the dechlorination reactions of CCl 4 by iron sulfide minerals and sulfide led to the hypothesis that :CCl 2 was slightly produced and subsequently hydrolyzed. 25,32 Notably, :CCl 2 cannot build up to high concentrations in hydrophilic environments stemming from strong hydrolysis or hydrogenolysis reaction.…”

Section: ■ Introductionmentioning

confidence: 99%

“…First, the graphitic regions of CMs have high electro-conductivity and can, thus, enhance electron transfer from sulfide to adsorbed HOCs ,– Second, the quinone moieties at the surface of CMs may act as electron shuttles to facilitate the electron transfer process though the quinone–hydroquinone redox cycling . Furthermore, the oxygenated functional groups (e.g., quinones and semiquinones) on CMs can oxidize sulfide to polysulfides, polysulfide free radicals, and other reactive sulfur species, which can reduce HOCs more quickly than sulfide. – …”

Section: Introductionmentioning

confidence: 99%

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New Mechanism via Dichlorocarbene Intermediate for Activated Carbon-Mediated Reductive Dechlorination of Carbon Tetrachloride by Sulfide in Aqueous Solutions

Wei,

Tao,

Zhu

2023

Environ. Sci. Technol.

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Although activated carbon (AC) is widely used as an adsorbent and barrier for contaminated sediment remediation, little attention has been paid to its mediation effects on reductive dechlorination of chlorinated solvents by commonly presenting sulfide. Here, we reported that highly porous, graphitized AC (250 mg L–1) suspended in deoxygenated aqueous solutions could increase the pseudo-first-order rate constant of sulfide-induced dechlorination of carbon tetrachloride (CCl4) by more than 1 order of magnitude. Carbon disulfide (CS2) was the only main product, with no production of chloroform or dichloromethane. The minimum promotion of CCl4 reduction observed with electro-conductive but nonporous graphite and a microporous but electro-insulative resin (XAD-4) indicates that graphitic carbons and micropores both play key roles in AC-mediated dechlorination of CCl4 by sulfide. The detection of dichlorocarbene (:CCl2) by free radical trapping experiments combined with the high suitability of the Langmuir–Hinshelwood model led us to propose a new mediation mechanism: CCl4 molecules adsorbed within the deep regions of AC micropores formed by graphitic carbons accept two electrons transferred from sulfide to form :CCl2, which is impeded from hydrolysis and hydrogenolysis by the hydrophobic micropore and further reacts with sulfide to generate CS2. Consistently, the production of :CCl2 was very low when AC was replaced with graphite or XAD-4. The proposed mechanism was further validated by the enhanced mediation effects of another two carbonaceous materials (template-synthesized mesoporous carbon and covalent triazine-based framework) that are electro-conductive and have well-developed micropore structures. These findings highlight the importance of pore properties of carbonaceous materials as mediators or catalysts for reductive dechlorination reactions and shed light on the development of coupled adsorption-reaction systems for remediation.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

New Mechanism via Dichlorocarbene Intermediate for Activated Carbon-Mediated Reductive Dechlorination of Carbon Tetrachloride by Sulfide in Aqueous Solutions

Wei,

Tao,

Zhu

2023

Environ. Sci. Technol.

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“…The kinetics in literatures about removal of pollutants are generally overviews, including various mechanisms. Thus, it is difficult to distinguish the kinetics between physical adsorption and chemical adsorption (Ding et al 2022;Luo et al 2022b). There many studies that pay attention to the elimination of a class of pollutants in soil and wastewater.…”

Section: Removal Mechanismsmentioning

confidence: 99%

Synthesis, characterization, safety design, and application of NPs@BC for contaminated soil remediation and sustainable agriculture

Zheng

Ouyang

Zhou

2023

Biochar

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Biochar (BC) and nanoparticle-decorated biochar (NPs@BC) have emerged as potential high-performance function materials to facilitate simultaneous soil remediation and agricultural production. Therefore, there is an urgent need to incorporate environmental sustainability and human health targets into BC and NPs@BC selection and design processes. In contrast to extensive research on the preparation, modification, and environmental application of BC to soil ecosystems, reports about the adapted framework and material selection strategy of NPs@BC under environmental and human health considerations are still limited. Nevertheless, few studies systematically explored the impact of NPs@BC on soil ecosystems, including soil biota, geochemical properties, and nutrient cycles, which are critical for large-scale utilization as a multifunctional product. The main objective of this systematic literature review is to show the high degrees of contaminant removal for different heavy metals and organic pollutants, and to quantify the economic, environmental, and toxicological outcomes of NPs@BC in the context of sustainable agriculture. To address this need, in this review, we summarized synthesis techniques and characterization, and highlighted a linkage between the evolution of NPs@BC properties with the framework for sustainable NPs@BC selection and design based on environmental effects, hazards, and economic considerations. Then, research advances in contaminant remediation for heavy metals and organic pollutants of NPs@BC are minutely discussed. Eventually, NPs@BC positively acts on sustainable agriculture, which is declared. In the meantime, evaluating from the perspective of plant growth, soil characterizations as well as carbon and nitrogen cycle was conducted, which is critical for comprehending the NPs@BC environmental sustainability. Our work may develop a potential framework that can inform decision-making for the use of NPs@BC to facilitate promising environmental applications and prevent unintended consequences, and is expected to guide and boost the development of highly efficient NPs@BC for sustainable agriculture and environmental applications. Graphical Abstract

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Carbonaceous Materials‐Based Photothermal Process in Water Treatment: From Originals to Frontier Applications

Hu,

Qin,

et al. 2023

Small

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The photothermal process has attracted considerable attention in water treatment due to its advantages of low energy consumption and high efficiency. In this respect, photothermal materials play a crucial role in the photothermal process. Particularly, carbonaceous materials have emerged as promising candidates for this process because of exceptional photothermal performance. While previous research on carbonaceous materials has primarily focused on photothermal evaporation and sterilization, there is now a growing interest in exploring the potential of photothermal effect‐assisted advanced oxidation processes (AOPs). However, the underlying mechanism of the photothermal effect assisted by carbonaceous materials remains unclear. This review aims to provide a comprehensive review of the photothermal process of carbonaceous materials in water treatment. It begins by introducing the photothermal properties of carbonaceous materials, followed by a discussion on strategies for enhancing these properties. Then, the application of carbonaceous materials‐based photothermal process for water treatment is summarized. This includes both direct photothermal processes such as photothermal evaporation and sterilization, as well as indirect photothermal processes that assisted AOPs. Meanwhile, various mechanisms assisted by the photothermal effect are summarized. Finally, the challenges and opportunities of using carbonaceous materials‐based photothermal processes for water treatment are proposed.

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N-doped biochar-catalyzed dechlorination of carbon tetrachloride in sulfide-containing aqueous solutions: Performances, mechanisms and pathways

Cited by 23 publications

References 49 publications

New Mechanism via Dichlorocarbene Intermediate for Activated Carbon-Mediated Reductive Dechlorination of Carbon Tetrachloride by Sulfide in Aqueous Solutions

New Mechanism via Dichlorocarbene Intermediate for Activated Carbon-Mediated Reductive Dechlorination of Carbon Tetrachloride by Sulfide in Aqueous Solutions

Synthesis, characterization, safety design, and application of NPs@BC for contaminated soil remediation and sustainable agriculture

Carbonaceous Materials‐Based Photothermal Process in Water Treatment: From Originals to Frontier Applications

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