Effect of modification with HNO3 and NaOH on metal adsorption by pitch-based activated carbon fibers

Shim, Jae-Woon; Park, Soo‐Jin; Ryu, Seung‐Kon

doi:10.1016/s0008-6223(00)00290-6

Cited by 480 publications

(258 citation statements)

References 18 publications

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“…Activated carbon has high surface area and porous structure, high adsorption capacity and can be easily functionalized and used as an efficient adsorbent for heavy metal contaminants. 28 The combination of magnetic iron phases with activated carbon offers an attractive and inexpensive option for the removal of different contaminants from water, such as pesticides, phenols and chlorophenols. [29][30][31][32] Magnetic composites of activated carbon/iron oxide were prepared with several weight ratios of 2:1, 1.5:1 and 1:1 and used for the adsorption of volatile organic compounds (VOCs) such as chloroform, phenol, chlorobenzene and dyes from aqueous solution.…”

Section: Application Of Iron Phases To Produce Magnetic Materials As mentioning

confidence: 99%

Iron: a versatile element to produce materials for environmental applications

Teixeira¹,

Tristão²,

Araújo³

et al. 2012

J. Braz. Chem. Soc.

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Ferro é um elemento versátil que forma várias fases com diferentes estados de oxidação e estruturas, tais como Fe 0 , FeO, Fe 3 O 4 , γ-Fe 2 O 3 , α-Fe 2 O 3 e FeOOH. Todas estas fases têm propriedades físico-químicas únicas que podem ser usadas para diferentes aplicações. Neste trabalho, descreve-se o uso de diferentes compostos de ferro, sintéticos e também naturais ou de rejeitos, em aplicações ambientais e tecnológicas. Duas áreas principais de pesquisa são descritas. A primeira é relacionada às estratégias para aumentar a reatividade de fases de ferro pela formação de compósitos Fe 0 /Fe óxido e pela introdução de novos metais na estrutura de óxidos de ferro para promover novas reações superficiais. A segunda área de pesquisa é o uso das propriedades magnéticas de algumas fases de ferro para produzir materiais magnéticos versáteis com aplicações focadas em adsorção, catálise e emulsões.Iron is a versatile element forming several phases with different oxidation states and structures, such as Fe 0 , FeO, Fe 3 O 4 , γ-Fe 2 O 3 , α-Fe 2 O 3 and FeOOH. All these phases have unique physicochemical properties which can be used for different applications. In this work, it is described the use of different iron compounds, synthetic and also from natural and waste sources, in environmental and technological applications. Two main research areas are described. The first one is related to strategies to increase the reactivity of Fe phases, mainly by the formation of Fe 0 /iron oxide composites and by the introduction of new metals in the iron oxide structure to promote new surface reactions. The second area is the use of the magnetic properties of some iron phases to produce versatile magnetic materials with focus in adsorption, catalysis and emulsions.

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Section: Application Of Iron Phases To Produce Magnetic Materials As mentioning

confidence: 99%

Iron: a versatile element to produce materials for environmental applications

Teixeira¹,

Tristão²,

Araújo³

et al. 2012

J. Braz. Chem. Soc.

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“…9,10 [surface] nH + + M n+ (aq) [surface] M n+ + nH + (aq) (1) AC chemical oxidation by nitric acids is one of the most effective means to provide acidic carboxylic and phenolic groups to AC surface. 10,11 However, due to the carbon surface heterogeneity, the carboxylic group introduced exhibits a range of acid dissociation constants (Ka), depending on the neighboring groups and the size of the graphene layer. As a result, the types of acidic groups (Ka) that display ion-exchange properties are insufficiently known.…”

Section: Introductionmentioning

confidence: 99%

Characterization of copper adsorption on oxidized activated carbon

Mesquita¹,

Martelli²,

Gorgulho³

2006

J. Braz. Chem. Soc.

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Esse artigo discute a adsorção de íon Cu(II) em carvão ativado oxidado com HNO 3 . As modificações introduzidas na superfície do carvão ativado (CA) foram caracterizadas por medidas de área superficial, espectroscopia de absorção no infravermelho, titulação pelo tradicional método de Boehm e titulação potenciométrica. Os dados da titulação potenciométrica foram ajustados através de um método não linear desenvolvido para determinar a concentração e distribuição do pKa dos sítios ácidos ionizáveis presentes na superfície do CA, antes e após a oxidação com HNO 3 . Os estudos de adsorção foram realizados em batelada para a faixa de concentração de 0,08 a 1,75 mmol L -1 em pH = 4,0. Os resultados mostraram que o tratamento do CA com ácido leva à diminuição na área superficial aparente e produz leves modificações na estrutura de poros. Entretanto, a oxidação influenciou fortemente a estrutura química da superfície do CA através do aumento na concentração de grupos ácidos com pKa < 6, causando assim uma melhora significativa na adsorção do íon Cu(II). A maior capacidade de adsorção do CA oxidado foi relacionada à presença de grupos ácidos com pKa < 4, revelando o importante papel destes grupos na adsorção pelo mecanismo de troca iônica. This paper discusses Cu(II) ion adsorption onto oxidized activated carbon with HNO 3 . The modifications introduced on the activated carbon (AC) surface were characterized by surface area measurement, FT-IR spectroscopy, titration by the traditional Boehm procedure, and potentiometric titration. A nonlinear method for fitting acid-base potentiometric titration data was applied to determine the concentration and pKa distributions of the ionizable acidic sites on AC, before and after HNO 3 oxidation. Adsorption studies were conducted in batch mode for the concentration range 0.08 to 1.75 mmol L -1 and pH = 4.0. Results showed that the acid treatment of AC leads to a decrease in apparent surface areas and produces slight modifications in pore structure. However, oxidation strongly influenced the AC surface chemical structures by increasing the concentration of acidic groups with pKa < 6.0, which significantly improved Cu(II) ion adsorption. The uptake enhanced for oxidized carbon was related to the presence of acidic groups with pKa lower than 4, revealing the important role of acidic groups in adsorption by ion-exchange mechanisms.

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“…The amount of Pb(II) adsorbed on oxidized ACF was dependent on the amount of surface acidic functional groups, especially carboxy groups. For the oxidized activated carbon, Pb(II) would adsorb onto carboxy groups on the surface because these oxygen acidic functional groups are widely known to act as effective adsorption sites for heavy metals [11,17]. Nevertheless, the value of Ke for 1500LD-13NOX-6 was slightly higher than that of 1500LD-8NOX-8, which was attributed to the fact that 1500LD-13NOX-6 had more amount of carboxy groups than the others.…”

Section: Pb(ii) Adsorption Isothermsmentioning

confidence: 97%

“…Furthermore, with the increases in nitric acid concentration and oxidation time, the reduction degree of specific surface area, total pore volume and micropore volume gradually increased. These results would be due to the pore entrance blockage by oxygen-containing surface functional groups or electrostatic repulsion between surface acidic functional groups and nitrogen gas, implying that these pores could not be evaluated with BET measurements in spite of the small molecular size of nitrogen gas [11]. Additionally, the decline of specific surface area might be attributed to the enlargement of micropore in the significantly interactive acid erosion.…”

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confidence: 99%