Monitoring Changes in Surface and Structural Properties of Porous Carbons Modified by Different Oxidizing Agents

Choma, J.; Burakiewicz-Mortka, W.; Jaroniec, Mietek; Li, Z; Klinik, J.

doi:10.1006/jcis.1999.6246

Cited by 66 publications

(53 citation statements)

References 28 publications

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“…According to them, water molecules are first adsorbed on primary adsorption centres (PAC) with oxygencontaining surface functionalities and then adsorption occurs on secondary sites with adsorbed water molecules. An increase in the water vapour pressure leads to the formation of clusters of associated water molecules via the hydrogen bonding Gun'ko 2005;Choma et al 1999). The isotherms obtained for the initial A2PS as well as for the water-treated samples can be assigned to type III of the IUPAC classification (Sing et al 1985) that is characteristic for weak adsorbent-adsorbate interactions.…”

Section: Resultsmentioning

confidence: 93%

“…The degree of AC oxidation and the type of created surface functionalities depends on chemical properties of oxidizing agent, oxidation temperature and time, as well as the chemical composition of the initial carbon materials (Jankowska et al 1991a;Marsh et al 1997;Gun'ko 2005;Choma et al 1999;Moreno-Castilla et al 1995). Small or large changes in the structural parameters of ACs depend on oxidation conditions (Jankowska et al 1991a;Marsh et al 1997;Gun'ko 2005;Choma et al 1999;Moreno-Castilla et al 1995;Gil et al 1997).…”

Section: Introductionmentioning

confidence: 99%

“…Small or large changes in the structural parameters of ACs depend on oxidation conditions (Jankowska et al 1991a;Marsh et al 1997;Gun'ko 2005;Choma et al 1999;Moreno-Castilla et al 1995;Gil et al 1997). There are many methods to enhance the surface functionality of ACs (Choma et al 1999). Despite numerous papers published on AC oxidation or other modifications, the using of new techniques can be perspective for these purposes.…”

Section: Introductionmentioning

confidence: 99%

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Hydrothermal modification of carbon adsorbents

et al. 2011

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The effects of high-pressure autoclave treatments on porous structure and surface properties were studied for a variety of activated carbons (AC, synthetic and produced from plum stones) treated with water vapour, hydrogen peroxide (10-50%) or 10% aqueous ammonia solution at relatively low temperatures (250, 350, 400 • C). Surface and structural parameters of modified ACs were determined using nitrogen, water, ammonia and benzene adsorption isotherms. It was found that the effects of AC modification resulting in changes in their porous structure and surface chemistry depend on the kind of initial ACs, modifier type and concentration of modifier and treatment temperature. At the same conditions synthetic ACs are modified to a larger extent than ACs prepared using natural raw materials. Repeated treatment of a given carbon intensifies changes in its porous structure.

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Section: Resultsmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Hydrothermal modification of carbon adsorbents

et al. 2011

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“…Moreover, Molina-Sabio et al [18] reported that the deposition of acidic groups on the entrance of the pores in the treated activated carbon could increase the weight up to 6 to 13 % depending upon the materials and the treatment conditions. However, the widening of the pore size of BC-AC indicates that the effective action of HNO3 causes significant damage to micropores of their structure and changes the surface area and also the pore volume [19]. Therefore, it can be concluded that liquid phase boiling nitric acid oxidation leads to fixation of acidic functional groups on modified BC surface and in the same time the partial destruction of porous structure has been occurred.…”

Section: Porosity and Surface Area Analysismentioning

confidence: 99%

Development of ion-exchange properties of bamboo charcoal modified with concentrated nitric acid

Khandaker

Kondo

Toyohara

et al. 2017

IOP Conf. Ser.: Earth Environ. Sci.

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Abstract. The surface chemistry and the structural properties of activated carbon can be altered by the acidic modification. The objective of this study is to investigate the changes occurring in bamboo charcoal (BC) during activation with concentrated nitric acid. Low temperature (500˚C) carbonized BC has been prepared and oxidized with 70% concentrated boiling nitric acid (BC-AC). The porous properties of the BC are analyzed with nitrogen adsorption isotherm at 77 K. The surface structure is observed by Field emission scanning electronic microscope (FESEM) and the surface functional groups are examined by Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and the pH of the point of zero charge (pHPZC). The results reveal that severe oxidation with HNO3 considerably decreases the surface area of BC with enhanced pore widening and FESEM observation demonstrates the erosive effect of oxidation. The FTIR analysis detects that some absorption bands are assigned for carboxyl, aldehyde and ketone groups on BC-AC. The XPS analysis also clearly shows that the ratio of oxygen and acidic functional groups has been enriched significantly on the BC-AC. The low pHPZC value of BC-AC confirms that the surface is highly acidic for the fixation of acidic functional groups on surface. In general, the existence of the abundant amount of acidic functional groups on adsorbents enhances the sorption of heavy metals ions in aqueous solution. Therefore, it is strongly expected that the modified BC, activated under the proposed conditions would be a promising ion exchanger in aqueous solution and can be applied for the adsorption of different heavy metal ions and radioactive materials from effluent.

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“…NaOCl, H 2 O 2 , HNO 3 , H 2 SO 4 ) and gaseous agents (e.g. N 2 O, H 2 O, O 2 ) can be found [18,[23][24][25][26]. The surface treatment with these activators usually results in the introduction of oxygen-containing surface moieties, such as carboxyl, carbonyl, phenolic, quinone and/or lactone [14,18,27].…”

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confidence: 99%

Chemically activated poly(furfuryl alcohol)-derived CMK-3 carbon catalysts for the oxidative dehydrogenation of ethylbenzene

Janus

Kuśtrowski

et al. 2014

Catalysis Today

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The surface of CMK-3 carbon, synthesized by the reversible replication of mesoporous silica (SBA-15) using poly(furfuryl alcohol) as a carbon precursor, was activated by wet oxidation with an aqueous solution of HNO 3 or H 2 O 2 . The process was performed at 50°C using solution containing different concentrations of the oxidizing agent. It was found that during the modification no significant changes in textural and structural properties of CMK-3 replica occurred. However, the treatment resulted in the formation of appreciable amounts of surface species containing oxygen. XPS and DRIFT spectroscopy allowed to identify and quantify the surface functional groups. Their stability was studied by TG-FTIR measurements. CO and CO 2 were found as main gaseous products evolved during thermal decomposition under inert atmosphere. Finally, the modified samples were tested in the catalytic oxidative dehydrogenation * Corresponding author. Tel. +48 12 6632006. Fax +48 12 6340515. E-mail address: kustrows@chemia.uj.edu.pl (P. Kuśtrowski) 2 of ethylbenzene to styrene at 350°C in the presence of oxygen as an oxidizing agent (at O 2 /ethylbenzene molar ratio of 1.0 and 3.0). At the beginning of the catalytic run, the highest styrene yield and selectivity was achieved at the lower O 2 content over the catalysts treated with nitric acid. Nevertheless, all studied catalysts underwent a gradual deactivation due to coke formation and changes in the distribution of surface moieties.

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Monitoring Changes in Surface and Structural Properties of Porous Carbons Modified by Different Oxidizing Agents

Cited by 66 publications

References 28 publications

Hydrothermal modification of carbon adsorbents

Hydrothermal modification of carbon adsorbents

Development of ion-exchange properties of bamboo charcoal modified with concentrated nitric acid

Chemically activated poly(furfuryl alcohol)-derived CMK-3 carbon catalysts for the oxidative dehydrogenation of ethylbenzene

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