Enhanced dechlorination of chlorobenzene compounds on fly ash: effects of metals, solvents, and temperature

Ghaffar, Abdul; Tabata, Masaaki

doi:10.1080/17518251003660139

Cited by 9 publications

(8 citation statements)

References 40 publications

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“…Thus, it could be predicted that a soil too dry would be impracticable for treatment. On the other hand, many metallic systems can be effective even in the presence of large quantities of water [123], and even in aqueous media [124]. At the same time, the importance of the chemisorptions of hydrogen ions or nascent hydrogen on metallic surfaces has been understood, and the process can somehow be improved by the addition of stabilizers such as polyvinylpyrrolidone [125] or even biochar [126].…”

Section: Discussionmentioning

confidence: 99%

Mechanistic Considerations on the Hydrodechlorination Process of Polychloroarenes

Mitoma¹,

Katayama²,

Simion³

2018

Organochlorine

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Defunctionalization of organochlorines through reductive dechlorination (also known as hydrodechlorination-replacement of chlorine atoms by hydrogen-is one of the main methodologies used in the detoxification of these harmful compounds. Most of the published papers on this particular matter focused on specific reagents, reaction conditions, and mainly result efficiency. Some of the authors were also concerned with reaction pathways (e.g., the order in which chlorine atoms were removed from a polychlorinated aromatic substrate-polychlorinated biphenyls, PCBs; polychlorinated dibenzo-p-dioxins, PCDDs; or polychlorinated dibenzofurans, PCDFs). However, the papers that dealt with the investigation of reaction mechanism were rather scarce. This chapter presents the advances made by researchers in understanding, from a mechanistic point of view, the hydrodechlorination process, along with our own assumptions. In doing so, it would be easier to predict the behavior of such compounds in a specific environment, showing more clearly the scope and limitations of each process, depending on the reaction conditions and reagents.

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Section: Discussionmentioning

confidence: 99%

Mechanistic Considerations on the Hydrodechlorination Process of Polychloroarenes

Mitoma¹,

Katayama²,

Simion³

2018

Organochlorine

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“…Consequently, emission sources of the most important and known polychlorinated dibenzo- p -dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs), known methods of reduction of emission to the atmosphere, the mechanism of dioxin formation in thermal processes and minimizing their formation removal from the stream of waste gases have been reviewed [ 271 ]. Higher dichlorination of PCDD/Fs can also be achieved in ambient temperature conditions, in the presence of metals, solvents and under ionic potential when microbes are limited [ 266 , 272 ]. A wide range of compounds are capable of PCDD/Fs formation which could be a de novo synthesis in the macromolecular carbon structures from various carbon species with various activated carbon such as, bituminous coal, charcoal, and fly ash.…”

Section: Introductionmentioning

confidence: 99%

Dehalogenases: From Improved Performance to Potential Microbial Dehalogenation Applications

et al. 2018

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The variety of halogenated substances and their derivatives widely used as pesticides, herbicides and other industrial products is of great concern due to the hazardous nature of these compounds owing to their toxicity, and persistent environmental pollution. Therefore, from the viewpoint of environmental technology, the need for environmentally relevant enzymes involved in biodegradation of these pollutants has received a great boost. One result of this great deal of attention has been the identification of environmentally relevant bacteria that produce hydrolytic dehalogenases—key enzymes which are considered cost-effective and eco-friendly in the removal and detoxification of these pollutants. These group of enzymes catalyzing the cleavage of the carbon-halogen bond of organohalogen compounds have potential applications in the chemical industry and bioremediation. The dehalogenases make use of fundamentally different strategies with a common mechanism to cleave carbon-halogen bonds whereby, an active-site carboxylate group attacks the substrate C atom bound to the halogen atom to form an ester intermediate and a halide ion with subsequent hydrolysis of the intermediate. Structurally, these dehalogenases have been characterized and shown to use substitution mechanisms that proceed via a covalent aspartyl intermediate. More so, the widest dehalogenation spectrum of electron acceptors tested with bacterial strains which could dehalogenate recalcitrant organohalides has further proven the versatility of bacterial dehalogenators to be considered when determining the fate of halogenated organics at contaminated sites. In this review, the general features of most widely studied bacterial dehalogenases, their structural properties, basis of the degradation of organohalides and their derivatives and how they have been improved for various applications is discussed.

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“…55 mS/cm; TDS 963 mg⋅dm −3 ; nitrates 57 ppm and the dissolved salt contents salinity was 0.1 ng⋅dm −3 . The sample was preserved and filtered as described in earlier studies [11][12][13][14]. The filtered sample was analysed on GC-ECD for lindane using internal standard technique as described by Zinovyev et al [19].…”

Section: Dechlorination Of Lindane Present In Industrialmentioning

confidence: 99%

“…In continuation of our previous work we developed a convenient and practicable method for dechlorination of lindane. According to our previous observations dechlorination of monochlorinated compounds always makes a problem as the compounds are very persistent to dechlorinate [11][12][13][14]. In this study reaction we carried out dechlorination in two phases; in first phase dechlorination was achieved through hydrodechlorination while in second phase substitution reactions were carried out to enhance dechlorination.…”

Section: Introductionmentioning

confidence: 99%

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Two-Phase Dechlorination/Detoxification of Lindane (Hexachlorocyclohexane)

Ghaffar

Tabata

Mashiatullah

2014

Advances in Environmental Chemistry

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Dechlorination of lindane was carried out in a two-phase reaction. In first phase Devarda's alloy and sodium borohydride were used in aqueous/ethanol reaction media. The reaction duration and temperature were optimized. In first phase higher dechlorination (78%) was achieved at 80 ∘ C with 40-minute reaction time and the products were chlorobenzene, dichlorobenzene, and chlorocyclohexane. In second phase, Ca(OH) 2 and sulfur were added in reaction media. The reactions conditions like temperature and reaction time were optimized. After 30 minutes, dechlorination was enhanced from 78% to 94% and the final products were benzene, phenol, catechol, benzenethiol, cyclohexane, cyclohexanol, and cyclohexanethiol. The results suggested that dechlorination of lindane in first and second phase was carried out through hydrodechlorination and substitution reactions, respectively. The developed method was applied for lindane containing real wastewater and higher dechlorination (91%) was achieved under optimized reaction conditions.

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Enhanced dechlorination of chlorobenzene compounds on fly ash: effects of metals, solvents, and temperature

Cited by 9 publications

References 40 publications

Mechanistic Considerations on the Hydrodechlorination Process of Polychloroarenes

Mechanistic Considerations on the Hydrodechlorination Process of Polychloroarenes

Dehalogenases: From Improved Performance to Potential Microbial Dehalogenation Applications

Two-Phase Dechlorination/Detoxification of Lindane (Hexachlorocyclohexane)

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