Effect of Oxygen Surface Groups on the Immersion Enthalpy of Activated Carbons in Liquids of Different Polarity

Rodríguez‐Reinoso, F.; Molina-Sabio, and M.; González, M.T.

doi:10.1021/la961047u

Cited by 80 publications

(40 citation statements)

References 18 publications

(32 reference statements)

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“…The values for benzene do not change with the number of groups, thus indicating that the decrease seen in Table 1 is due to the decrease produced in the volume of micropores and surface area. Consequently, the results confirm that the chemical nature of the carbon does not affect the interactions with a non-polar molecule such as benzene, this not being the case for ethylenediamine or water [17][18][19]. There is in both cases a decrease of the order of 15%, which is mainly due to the decrease in groups evolving as CO, those affecting to a larger extent the enthalpy of immersion in water [17].…”

Section: Figuresupporting

confidence: 54%

“…Consequently, the results confirm that the chemical nature of the carbon does not affect the interactions with a non-polar molecule such as benzene, this not being the case for ethylenediamine or water [17][18][19]. There is in both cases a decrease of the order of 15%, which is mainly due to the decrease in groups evolving as CO, those affecting to a larger extent the enthalpy of immersion in water [17]. [20,21]: the uptake of water at low relative pressures is almost nil and a significant uptake occurs only at relative pressure above 0.5.…”

Section: Figuresupporting

confidence: 52%

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Modification of activated carbon hydrophobicity by pyrolysis of propene

Gonçalves

Molina‐Sabio

Rodriguez-Reinoso

2010

Journal of Analytical and Applied Pyrolysis

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The chemical nature of the surface of a granular activated carbon has been modified by heat treatment under nitrogen at 1000ºC followed by pyrolysis of propene in the 300-600ºC temperature range. Cracking of propene produces deposits of coke on the more reactive sites of the carbon surface, those produced after the decomposition of the original oxygen surface groups along the previous heat treatment. The process leads to an initial reduction in the number of oxygen surface groups and in the capacity of the carbon to chemisorb oxygen. The further growth of the carbon deposit in the interior of the particle decreases the width of the micropore entrance, which is paralleled by the coating of the external surface of the particle. The reduction in the number of active sites of the carbon leads to a decrease in the enthalpy of immersion into polar liquids such as water and ethylenediamine, the carbon becoming more hydrophobic than the original.

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Section: Figuresupporting

confidence: 54%

Section: Figuresupporting

confidence: 52%

Modification of activated carbon hydrophobicity by pyrolysis of propene

Gonçalves

Molina‐Sabio

Rodriguez-Reinoso

2010

Journal of Analytical and Applied Pyrolysis

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“…In addition to untreated samples, the soot has been subjected to simulated [7] and Bradley et al [5].…”

Section: Introductionmentioning

confidence: 99%

The Wetting Behavior of Fresh and Aged Soot Studied through Contact Angle Measurements

Wei¹,

Zhang²,

Thompson³

2017

ACS

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In this work, contact angle measurements for soot samples collected from a kerosene lantern, wood-burning fireplace, and municipal bus engine exhaust lines are reported. Contact angles for both freshly collected soot and samples treated with various doses of O 3 (g), HNO 3 (g), and H 2 SO 4 (g) are considered. Use of a literature method has allowed estimation of the enthalpy of immersion (H imm ) for the soot samples based on contact angle observed. Contact angles for freshly collected soot were 65 -110 deg. indicating its hydrophobic nature. Chemical processing of soot usually resulted in smaller contact angles and large increases in immersion enthalpy. However, the dose of ozone, nitric or sulfuric acid vapor required to achieve alteration of the soot surface appeared to be considerably larger than that expected to be experienced by authentic atmospheric samples during the soot particles lifetime. The most significant variability of soot contact angle was observed for the municipal bus exhaust samples, suggesting that combustion chemistry may significantly affect wetting behavior.

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“…2b). In oxygen-free atmosphere, groups with oxygen and water present on the surface of the activated carbon should decompose with evolution of CO 2 , CO and H 2 O [29][30][31]. Water, which is adsorbed on the surface of the material, should evaporate at the beginning of the measurement (between 40 and 200°C).…”

Section: Thermal Gravimetric Analysismentioning

confidence: 99%

Persulfate treatment as a method of modifying carbon electrode material for aqueous electrochemical capacitors

Kopczyński

Pęziak-Kowalska

Lota

et al. 2016

J Solid State Electrochem

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The activated carbon was modified by the wet method with a solution of ammonium persulfate at room temperature with different times. Kinetics studies showed that the modification took place mostly during the first 60 min of the process. The physicochemical properties of the obtained carbon were evaluated by thermogravimetric studies, Raman and FTIR spectroscopy, elementary and BET analyses. Furthermore, the fabricated material was applied in symmetric capacitors operated on the three aqueous electrolytes (1 M H 2 SO 4 , 6 M KOH and 1 M Na 2 SO 4 ). Mild conditions of the modification process are optimal to obtain electroactive groups on the carbon surface, which make this material useful in a supercapacitor application. In our studies, we noticed that this type of functional groups mainly appears on the surface of the activated carbon, in the first oxidation stage. With prolonged oxidation, they may transform into undesirable groups. The results show that this kind of modification improves the capacity of all the tested supercapacitors. It was connected mainly with an increase of the carbon material's wettability and in the case of capacitor operated in acid and base electrolytes due to a redox reaction of oxygen functional groups.

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Effect of Oxygen Surface Groups on the Immersion Enthalpy of Activated Carbons in Liquids of Different Polarity

Cited by 80 publications

References 18 publications

Modification of activated carbon hydrophobicity by pyrolysis of propene

Modification of activated carbon hydrophobicity by pyrolysis of propene

The Wetting Behavior of Fresh and Aged Soot Studied through Contact Angle Measurements

Persulfate treatment as a method of modifying carbon electrode material for aqueous electrochemical capacitors

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