Intensification of catalytic wet peroxide oxidation with microwave radiation: Activity and stability of carbon materials

Garcia-Costa, Alicia L.; Zazo, Juan A.; Rodrı́guez, Juan J.; Casas, José A.

doi:10.1016/j.seppur.2018.07.054

Cited by 26 publications

(6 citation statements)

References 32 publications

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“…AOP are based on the use of strong oxidizing radicals to degrade, most commonly, organic pollutants in aqueous phase [11]. The most extended AOP are those based on the use of hydroxyl radicals (HO • ) to attack organic pollutants by hydrogen abstraction [12]. Consequently, the substitution of all organic hydrogen for fluorine in PFOA makes these compounds inert to this kind of AOP.…”

Section: Introductionmentioning

confidence: 99%

On the Role of the Cathode for the Electro-Oxidation of Perfluorooctanoic Acid

et al. 2020

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Perfluorooctanoic acid (PFOA), C7F15COOH, has been widely employed over the past fifty years, causing an environmental problem because of its dispersion and low biodegradability. Furthermore, the high stability of this molecule, conferred by the high strength of the C-F bond makes it very difficult to remove. In this work, electrochemical techniques are applied for PFOA degradation in order to study the influence of the cathode on defluorination. For this purpose, boron-doped diamond (BDD), Pt, Zr, and stainless steel have been tested as cathodes working with BDD anode at low electrolyte concentration (3.5 mM) to degrade PFOA at 100 mg/L. Among these cathodic materials, Pt improves the defluorination reaction. The electro-degradation of a PFOA molecule starts by a direct exchange of one electron at the anode and then follows a complex mechanism involving reaction with hydroxyl radicals and adsorbed hydrogen on the cathode. It is assumed that Pt acts as an electrocatalyst, enhancing PFOA defluorination by the reduction reaction of perfluorinated carbonyl intermediates on the cathode. The defluorinated intermediates are then more easily oxidized by HO• radicals. Hence, high mineralization (xTOC: 76.1%) and defluorination degrees (xF−: 58.6%) were reached with Pt working at current density j = 7.9 mA/cm2. This BDD-Pt system reaches a higher efficiency in terms of defluorination for a given electrical charge than previous works reported in literature. Influence of the electrolyte composition and initial pH are also explored.

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Section: Introductionmentioning

confidence: 99%

On the Role of the Cathode for the Electro-Oxidation of Perfluorooctanoic Acid

et al. 2020

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“…These results might be due to strong binding between 2,4-D and biochar via diffusion into the inner porous structure and intensive chemisorption by the surface functionalities of biochar [40]. In addition, the 1-min TOC removal (59.2 ±2.5, It is also possible that the carbon materials eventually crumble when "hot spots" formed inside micropores generate sufficient confined vapour with increased pressure [6]. This so-called "popcorn effect" could impede biochar stability with susceptible deactivation and fouling by intermediates [6].…”

Section: Desorption and Reusability Of The Biocharsmentioning

confidence: 99%

“…In addition, the 1-min TOC removal (59.2 ±2.5, It is also possible that the carbon materials eventually crumble when "hot spots" formed inside micropores generate sufficient confined vapour with increased pressure [6]. This so-called "popcorn effect" could impede biochar stability with susceptible deactivation and fouling by intermediates [6]. Future studies should focus on biochar regeneration via facile and low-cost treatment, for example, low-temperature heating in N2 environment or desorption by various types of green solvents.…”

Section: Desorption and Reusability Of The Biocharsmentioning

confidence: 99%

“…The thermal effect of MW irradiation may produce "hot spots" or micro-plasmas that ionize the surrounding atmosphere [6], which can accelerate organic decomposition and generate highly oxidative hydroxyl radicals ( • OH) [4,6]. MW irradiation treatment presents advantages compared to other heating techniques of easy operation, improved processing efficiency, reduced energy and chemical consumption, shortened reaction time, and complete mineralization of organic contaminants [3,7].…”

Section: Introductionmentioning

confidence: 99%

“…MW catalysts usually consist of a single (or binary/ternary) metallic phase (e.g., Fe [8], Cu [9], Mn [10], Ni [11], Ti [12], Co [13], and Bi [14]), supported on porous, conductive materials (e.g., activated carbon (AC) [15], mesoporous carbon [16], reduced graphene oxide (rGO) [17], and minerals [18]), which favour dispersion of metals/metal oxides and accelerate recycling of metal redox pairs [17]. Nonetheless, these catalysts are prone to deactivation via metal leaching/detachment creating a new environmental problem [6].…”

Section: Introductionmentioning

confidence: 99%

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Tailored design of graphitic biochar for high-efficiency and chemical-free microwave-assisted removal of refractory organic contaminants

Sun

Tsang

et al. 2020

Chemical Engineering Journal

108

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Energy-saving, chemical-free, and high-efficiency microwave (MW)-assisted water treatment can be greatly facilitated via tailored design of an economical, sustainable, and 'green' carbonaceous catalyst. In this study, various biochars (BC) were pyrolyzed from two lignocellulosic waste biomasses, oak (O) and apple tree (A), at high temperature (900 °C) and under different gases (N2 and CO2). The holistic characterization by advanced spectroscopic techniques demonstrated that CO2 pyrolysis of feedstock with more lignin (i.e., oak), produced biochar with increased aromaticity and degree of carbonization. CO2 modification created a hierarchical porous structure, improved surface hydrophilicity, polarity, and acidity, and provided higher ManuscriptClick here to view linked References 2 densities of near-surface functionalities of the biochar. Without MW irradiation, ABC-900C (1 g L −1 ) provided the highest adsorption (52.6%, 1 min) of 2,4-dichlorophenoxy acetic acid (2,4-D) ascribed to large specific surface area, high micropore content, appropriate pore size, and abundant active groups. OBC-900C(1 g L −1 ) enabled significantly increased 2,4-D removal (81.6%, 1 min) under MW irradiation (90 °C) in contrast with an oil bath (55.7%, 90 °C, 1 min) and room temperature (33.9%, 1 min) conditions, due to its highest graphitization degree and medium-developed microporous structure. The MW-induced thermal effect formed "hot spots" on the biochar surface as evidenced by elevated temperature of the bulk solution and lowered energy consumption of the MW reactor in the presence of OBC-900C, compared to those of the other biochars. The scavenging tests suggested that the generation of highly oxidative hydroxyl ( • OH), anionic superoxide (O2 •− ), and singlet oxygen ( 1 O2) radicals contributed to the removal of 2,4-D. This study has demonstrated that biochar with customized structure and high organic adsorption capacity can act as an effective MW absorber suitable for rapid and improved removal of toxic organics.

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Treatment of Integrated Steel Plant Wastewater Using Conventional and Advanced Techniques

Kumar

Gopinath

Ranjith

et al. 2022

CLEAN Soil Air Water

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The integrated steel industry is considered as one of the important industrial sectors, and its outputs are inputs for other sectors including construction, engineering, medical and scientific equipment, and defence. Massive production, consumption, and export of steel signify a country's economic index. This review outlines the World's steel production quantities, the processes involved, and wastewater generation from the industry and its treatment. Wastewater generated from steel plants is highly complex and requires intensive treatment before discharge into natural water bodies. Technologies adopted for treating wastewater generated from steel industries are deliberated, focusing on coking wastewater treatment. Microbial mediated processes provide an effective means of degrading the contaminants, but the toxicity of certain compounds during higher pollutant load inhibits its further treatment. However, these processes can be integrated with either electrochemical technologies or advanced oxidation processes (AOPs), which can reduce the toxicity level. Hence, when a highly concentrated and complex mixture of contaminants is considered, an integrated approach is a resourceful option in terms of cost‐effectiveness and treatment efficiency.

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Intensification of catalytic wet peroxide oxidation with microwave radiation: Activity and stability of carbon materials

Cited by 26 publications

References 32 publications

On the Role of the Cathode for the Electro-Oxidation of Perfluorooctanoic Acid

On the Role of the Cathode for the Electro-Oxidation of Perfluorooctanoic Acid

Tailored design of graphitic biochar for high-efficiency and chemical-free microwave-assisted removal of refractory organic contaminants

Treatment of Integrated Steel Plant Wastewater Using Conventional and Advanced Techniques

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