Abstract:The characterization of fluorinated carbon fibers by water sorption has been broadly investigated in this work. In brief, a pitch-based activated carbon fiber (ACF) was submitted to a fluorination process under different conditions of partial pressure (F2:N2 ratio) and temperature. This led to samples with varied fluorine content and C-F type bonding. The effect of the fluorination treatment on the textural properties of the ACF was studied by means of nitrogen and carbon dioxide adsorption at −196 and 0°C, re… Show more
“…Figure 2 D illustrates the high-resolution C 1s spectra of F-AC, wherein an additional peak corresponding to the C–F bond (289.8 eV) was observed, which was not detected for AC. 46 The relatively high C–F binding energy was due to the large electronegativity difference between the components; the electronegativity difference enhanced the conductivity of the activated carbon by facilitating charge transfer between fluorine and carbon. 47 , 48 Thus, the XPS results revealed that the doping of fluorine atoms on AC was successful in fabricating F-AC.…”
Residues of oxytetracycline (OTC), a veterinary antibiotic
and
growth promoter, can be present in animal-derived foods; their consumption
is harmful to human health and their presence must therefore be detected
and regulated. However, the maximum residue limit is low, and consequently
highly sensitive and accurate detectors are required to detect the
residues. In this study, a novel highly sensitive electrochemical
sensor for the detection of OTC was developed using a screen-printed
electrode modified with fluorine-doped activated carbon (F-AC/SPE)
combined with a novel deep eutectic solvent (DES). The modification
of activated carbon by doping with fluorine atoms (F-AC) enhanced
the adsorption and electrical activity of the activated carbon. The
novel hydrophobic DES was prepared from tetrabutylammonium bromide
(TBABr) and a fatty acid (malonic acid) using a green synthesis method.
The addition of the DES increased the electrochemical response of
F-AC for OTC detection; furthermore, it induced preconcentration of
OTC, which increased its detectability. The electrostatic interactions
between DES and OTC as well as the adsorption of OTC on the surface
of the modified electrode through H-bonding and π–π
interactions helped in OTC detection, which was quantified based on
the decrease in the anodic peak potential (E
pa = 0.3 V) of AC. The electrochemical behavior of the modified
electrode was investigated by cyclic voltammetry, differential pulse
voltammetry, and electrochemical impedance spectroscopy. Under optimum
conditions, the calibration plot of OTC exhibited a linear response
in the range 5–1500 μg L–1, with a
detection limit of 1.74 μg L–1. The fabricated
electrochemical sensor was successfully applied to determine the OTC
in shrimp pond and shrimp samples with recoveries of 83.8–100.5%
and 93.3–104.5%, respectively. In addition to the high sensitivity
of OTC detection, the proposed electrochemical sensor is simple, cost-effective,
and environmentally friendly.
“…Figure 2 D illustrates the high-resolution C 1s spectra of F-AC, wherein an additional peak corresponding to the C–F bond (289.8 eV) was observed, which was not detected for AC. 46 The relatively high C–F binding energy was due to the large electronegativity difference between the components; the electronegativity difference enhanced the conductivity of the activated carbon by facilitating charge transfer between fluorine and carbon. 47 , 48 Thus, the XPS results revealed that the doping of fluorine atoms on AC was successful in fabricating F-AC.…”
Residues of oxytetracycline (OTC), a veterinary antibiotic
and
growth promoter, can be present in animal-derived foods; their consumption
is harmful to human health and their presence must therefore be detected
and regulated. However, the maximum residue limit is low, and consequently
highly sensitive and accurate detectors are required to detect the
residues. In this study, a novel highly sensitive electrochemical
sensor for the detection of OTC was developed using a screen-printed
electrode modified with fluorine-doped activated carbon (F-AC/SPE)
combined with a novel deep eutectic solvent (DES). The modification
of activated carbon by doping with fluorine atoms (F-AC) enhanced
the adsorption and electrical activity of the activated carbon. The
novel hydrophobic DES was prepared from tetrabutylammonium bromide
(TBABr) and a fatty acid (malonic acid) using a green synthesis method.
The addition of the DES increased the electrochemical response of
F-AC for OTC detection; furthermore, it induced preconcentration of
OTC, which increased its detectability. The electrostatic interactions
between DES and OTC as well as the adsorption of OTC on the surface
of the modified electrode through H-bonding and π–π
interactions helped in OTC detection, which was quantified based on
the decrease in the anodic peak potential (E
pa = 0.3 V) of AC. The electrochemical behavior of the modified
electrode was investigated by cyclic voltammetry, differential pulse
voltammetry, and electrochemical impedance spectroscopy. Under optimum
conditions, the calibration plot of OTC exhibited a linear response
in the range 5–1500 μg L–1, with a
detection limit of 1.74 μg L–1. The fabricated
electrochemical sensor was successfully applied to determine the OTC
in shrimp pond and shrimp samples with recoveries of 83.8–100.5%
and 93.3–104.5%, respectively. In addition to the high sensitivity
of OTC detection, the proposed electrochemical sensor is simple, cost-effective,
and environmentally friendly.
“…The water vapor adsorption capacity of the LACF was significantly higher at 0.40 g/g, compared to those of the other two. Thus, LACF had better adsorption capacity for water vapor under the same temperature and humidity conditions, and its water vapor adsorption capacity is also higher than that of the commercial pitch-based activated carbon fiber (0.35 g/g) (Velasco et al 2021 ). Fig.…”
Lignin is a renewable bioresource that can be used for a variety of value-added applications. However, the effective separation of lignin from lignocellulosic biomass remains an ongoing challenge. In this study, lignin was extracted from waste palm fiber and successfully converted into a dehumidifying material. The following four process parameters of lignin extraction from palm fiber were optimized systematically and comprehensively using the response surface methodology: reaction time, extraction temperature, ethanol concentration and solid/liquid ratio. The results revealed that under the optimum processing conditions (111 min of extraction at 174 °C using 73% ethanol at 1/16 g/mL solid/liquid ratio), the extraction yield of lignin was 56.2%. The recovery of ethanol solvent was as high as 91.8%. Further, the lignin could be directly used without purification to produce lignin-based activated carbon fibers (LACFs) with specific surface area and total pore volume of 1375 m2/g and 0.881 cm3/g, respectively. Compared with the commercial pitch-based activated carbon fiber, the LACF has a higher specific area and superior pore structure parameters. This work provides a feasible route for extracting lignin from natural palm fiber and demonstrates its use in the preparation of activated carbon fiber with a remarkable performance as a solid dehumidification agent.
Graphical Abstract
“…The enhancement of hydrophilicity of porous carbon materials can occur with fluorination under certain conditions, that is, applying gaseous diluted fluorine with nitrogen. [ 53 ] The enhancement of the hydrophobic character of the fluorinated sample is however the main case and was proved through higher relative adsorption pressure and its incomplete filling (56%) even at saturation pressure. [ 54 ] Superhydrophobicity can even be obtained and valuable for water management in hydrogen fuel cells.…”
Section: Fluorination Of Porous Carbonaceous Materialsmentioning
The benefits of covalent grafting of fluorine atoms onto carbonaceous materials are described for the design of new electrocatalysts for low‐temperature fuel cells. In order to obtain the best results, the fluorination conditions must be carefully chosen according to the physicochemical properties of the starting materials (specific surface area, pore size distribution, crystallinity, and doping). By describing the main fluorination routes, the article aims to help in the choice of efficient treatment conditions. The effects of fluorination on the performance of the platinum group metal (PGM)‐based catalyst and the non‐PGM‐based electrocatalyst are discussed. Finally, future research prospects and technical challenges of fluorination for fuel cells are proposed.
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