The influence of active carbon contaminants on the ozonation mechanism interpretation

AbstractIn water treatment technology, activated carbons are used primarily as sorbents to remove organic impurities, mainly natural organic matter, but also as catalysts in the ozonation process. Commercially available activated carbons are usually contaminated with mineral substances, classified into two main groups: alkali metals (Ca, Na, K, Li, Mg) and multivalent metals (Al, Fe, Ti, Si). The presence of impurities on the carbon surface significantly affects the pHpzc values determined for raw and ozonated carbon as well as their acidity and alkalinity. The scale of the observed changes strongly depends on the pH of the ozonated system, which is related to the diffusion of impurities from the carbon to the solution. In an acidic environment (pH 2.5 in this work), the ozone molecule is relatively stable, yet active carbon causes its decomposition. This is the first report that indirectly indicates that contaminants on the surface of activated carbon (multivalent elements) contribute to the breakdown of ozone towards radicals, while the process of ozone decomposition by purified carbons does not follow the radical path in bulk solution. Carbon impurities also change the distribution of the reaction products formed by organic pollutants ozonation, which additionally confirms the radical process. The study showed that the use of unpurified activated carbon in the ozonation of succinic acid (SA) leads to the formation of a relatively large amount of oxalic acid (OA), which is a product of radical SA degradation. On the other hand, in solutions with purified carbon, the amount of OA generated is negligible.

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The Effect of Sulphur Dioxide Exposure under Controlled Environmental Conditions on the Challenge Performance of Copper and Chromate Impregnated Active Carbon against Hydrogen Cyanide

Adsorption Science & Technology ◽

10.1177/026361749701500706 ◽

1997 ◽

Vol 15 (7) ◽

pp. 531-540 ◽

Cited By ~ 3

Author(s):

P.J.C. Anstice ◽

J.F. Alder

Keyword(s):

Activated Carbon ◽

Numerical Analysis ◽

Flow Rate ◽

Active Carbon ◽

Environmental Conditions ◽

Sulphur Dioxide ◽

Hydrogen Cyanide ◽

Carbon Surface ◽

Adsorption Model ◽

Active Centres

An ASC/T (Cu2+, Cr6+, Ag and triethylenediamine impregnated) Whetlerite activated carbon sample was exposed to a flow rate of 1 l/min, 0.746 mg/l SO2 in 80% RH air at 22°C for up to 510 min. Samples were subsequently challenged with 2 mg/l HCN in an identical diluent gas stream. Increasing SO2 exposure resulted in accelerated HCN and (CN)2 bed penetration. The basic shapes of the breakthrough profiles were however essentially unchanged. This observation is in accordance with numerical analysis of these results using Hinshelwood's adsorption model, which suggested that the adsorption rate constant was not significantly affected by SO2 but rather the pollutant exposure resulted in the number of active centres on the carbon surface being reduced and the effective bed depth of the sample being shortened. This loss in active centres was thought most likely to result from the reduction of Cr6+ to Cr3+.

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Quinone/hydroquinone redox couple as a source of enormous capacitance of activated carbon electrodes

MRS Proceedings ◽

10.1557/opl.2013.268 ◽

2013 ◽

Vol 1505 ◽

Cited By ~ 2

Author(s):

Krzysztof Fic ◽

Mikolaj Meller ◽

Grzegorz Lota ◽

Elzbieta Frackowiak

Keyword(s):

Activated Carbon ◽

Redox Reactions ◽

Electrode Materials ◽

Activated Carbons ◽

Hydroxyl Group ◽

Carbon Surface ◽

Carbon Electrodes ◽

Main Subject ◽

Solution Ph ◽

Reversible Redox

ABSTRACTThe main subject of this paper is to examine and to evaluate the capacitive behaviour of activated carbon electrodes electrochemically decorated by quinone-type functional groups. For this purpose, different electrolytes, i.e. hydroquinone, catechol and resorcinol at the concentration of 0.38 mol L-1, dissolved in 1 mol L-1 H2SO4, 1 mol L-1 Li2SO4 and 6 mol L-1 KOH were used. These electrolytes could generate electroactive groups (able to undergo reversible redox reactions) on the surface of electrode material. Apart from typical adsorption of the mentioned dihydroxybenzenes, so called grafting could occur and might cause generation of quinone|hydroquinone functionals on carbon surface. As an effect of functional reversible redox reaction, additional capacitance value, called pseudocapacitance, could be achieved. Hence, besides typical charge originating from charging/discharging of the electrical double layer on the electrode/electrolyte interface, additional capacitance comes also from faradaic reactions. Activated carbons are the most promising electrode materials for this purpose; apart from great physicochemical properties, they are characterized by well-developed specific surface area over 2000 m2 g-1 which results in high capacitance values.In the manuscript the influence of the hydroxyl group location as well as electrolyte solution pH on the electrochemical performance of the electrode is discussed.

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Coal-Based Activated Carbons for the Removal of Sulphur Dioxide via Adsorption

Adsorption Science & Technology ◽

10.1177/026361749701501006 ◽

1997 ◽

Vol 15 (10) ◽

pp. 803-814 ◽

Cited By ~ 4

Author(s):

A.M. Youssef ◽

M.R. Mostafa ◽

E.M. Dorgham

Keyword(s):

Activated Carbon ◽

Low Temperature ◽

Zinc Chloride ◽

Sulphur Dioxide ◽

Activated Carbons ◽

Textural Properties ◽

Nitrogen Adsorption ◽

Carbon Surface ◽

Steam Activation ◽

Pore Widening

Zinc chloride-activated carbons and steam-activated carbons were prepared from Maghara coal. The textural properties were determined from low-temperature nitrogen adsorption. Zinc chloride activation is usually associated with the creation of new micropores while steam activation involves pore widening particularly when the percentage burn-off is high. The adsorption of SO2 on steam-activated carbon is high compared with ZnCl2-activated carbons. Steam activation develops surface basic groups which provide chemisorption sites for SO2. The adsorption of SO2 is enhanced in the presence of O2 and water vapour and involves the formation of sulphuric acid in this case. Sulphur dioxide adsorption is related to the chemistry of the carbon surface rather than to the extent of the surface area of the activated carbon.

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SURFACE MODIFICATIONS OF ACTIVATED CARBON AND ITS IMPACT ON APPLICATION

Surface Review and Letters ◽

10.1142/s0218625x1830006x ◽

2019 ◽

Vol 26 (01) ◽

pp. 1830006 ◽

Cited By ~ 2

Author(s):

MATHEUS PEGO ◽

JANAÍNA CARVALHO ◽

DAVID GUEDES

Keyword(s):

Surface Modification ◽

Activated Carbon ◽

Surface Chemistry ◽

Surface Structure ◽

Adsorption Capacity ◽

Activated Carbons ◽

Surface Modifications ◽

Hazardous Substances ◽

Carbon Surface ◽

Corona Treatment

The main and new surface modification methods of activated carbon (AC) and their influence on application (adsorption capacity) were reviewed. Adsorption capacity is an important issue, contributing to hazardous substances environment management. According to literature, it is true that surface chemistry strongly affects adsorption capacity. Surface chemistry can be modified by several methods that lead to different activated carbon properties. Furthermore, adsorbate properties, and their relationships with surface structure, can impact adsorption properties. Surface modifications can be conducted by adding some atoms to the surface structure, making the surface more acidic or basic. Introduction of oxygen and ammonia atoms (chemical modification) are the main processes to make the surface more acidic and basic, respectively, although may bring chemical wastes to environment. Surface modification is done by chemical and physical modifications that lead activated carbons to present different properties. The main and new methods of chemical and physical modifications are compared and presented in this paper. Some new physical methods, like corona treatment, plasma discharge and microwave radiation, can be applied to cause surface modifications. Corona treatment can be a practical and new way to cause surface modification on an activated carbon surface.

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Activated Carbon from Corncobs Doped with RuO2 as Biobased Electrode Material

Electronic Materials ◽

10.3390/electronicmat2030023 ◽

2021 ◽

Vol 2 (3) ◽

pp. 324-343

Author(s):

Viola Hoffmann ◽

Catalina Rodriguez Correa ◽

Saskia Sachs ◽

Andrea del Pilar Sandoval-Rojas ◽

Mo Qiao ◽

...

Keyword(s):

Activated Carbon ◽

Electrochemical Properties ◽

Activated Carbons ◽

Chemical Activation ◽

Xrd Analysis ◽

High Specific Surface Area ◽

Carbon Surface ◽

Physico Chemical ◽

Electrochemical Double Layer Capacitors ◽

Electrochemical Double Layer

Bio-based activated carbons with very high specific surface area of >3.000 m² g−1 (based on CO2 adsorption isotherms) and a high proportion of micropores (87% of total SSA) are produced by corncobs via pyrolysis and chemical activation with KOH. The activated carbon is further doped with different proportions of the highly pseudocapacitive transition metal oxide RuO2 to obtain enhanced electrochemical properties and tune the materials for the application in electrochemical double-layer capacitors (EDLC) (supercapacitors). The activated carbon and composites are extensively studied regarding their physico-chemical and electrochemical properties. The results show that the composite containing 40 wt.% RuO2 has an electric conductivity of 408 S m−1 and a specific capacitance of 360 Fg−1. SEM-EDX, XPS, and XRD analysis confirm the homogenous distribution of partly crystalline RuO2 particles on the carbon surface, which leads to a biobased composite material with enhanced electrochemical properties.

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The interaction of metallic ions onto activated carbon surface using computational chemistry software

Adsorption Science & Technology ◽

10.1177/0263617420919234 ◽

2020 ◽

Vol 38 (5-6) ◽

pp. 191-204

Author(s):

AL Paredes-Doig ◽

A Pinedo-Flores ◽

J Aylas-Orejón ◽

D Obregón-Valencia ◽

MR Sun Kou

Keyword(s):

Activated Carbon ◽

Metal Ions ◽

Electron Density ◽

Activated Carbons ◽

Surface Acidity ◽

Chemical Activation ◽

Carbon Surface ◽

Maximum Adsorption Capacity ◽

Metallic Ions ◽

Oxidized Activated Carbon

Activated carbon was prepared from the seeds of aguaje palm ( Mauritia flexuosa L.f.) by a chemical activation with phosphoric acid. This activated carbon was used for adsorbing metal ions: Pb(II), Cd(II), and Cr(III). To understand the mechanism of adsorption of these heavy metals (Cr, Cd, and Pb), the activated carbon surface was oxidized with nitric acid (1 M) increasing the oxygenated surface groups showing an increasing in their adsorption capacities of these metals. The oxidized activated carbon slightly increased the maximum adsorption capacity to 5–7%. The order of adsorption for unoxidized and oxidized activated carbons was Pb> Cd> Cr. This experimental information was corroborated by molecular modeling program Hyperchem 8 based adsorption mainly on two factors: the electron density and orbitals—highest occupied molecular orbital and lowest unoccupied molecular orbital.Activated carbons were characterized by adsorption/desorption of N2, obtaining an increase of microporous surface area for oxidized activated carbon. An increase of surface acidity and a reduction of isoelectric points were observed in oxidized activated carbon. According to these results, the adsorption of metal ions is favored in contact with an oxidized activated carbon, which has more amount of phenolic and carboxylic functional groups. Similarly, decreasing the isoelectric point indicates that the surface has a higher negative charge. The surface information was corroborated by Hyperchem, which indicates that the surface of the oxidized activated carbon has a higher electron density, indicating a larger amount of electrons on its surface, which means the surface of oxidized activated carbon charges negatively and thereby attracts metal ions.

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Relationship between the Activated Carbon Surface Area and Adsorption Model Coefficients for Removal of Phenol from Water

Water Quality Research Journal ◽

10.2166/wqrj.1995.030 ◽

1995 ◽

Vol 30 (2) ◽

pp. 325-338 ◽

Cited By ~ 2

Author(s):

Peter Samaras ◽

Evan Diamadopoulos ◽

George P. Sakellaropoulos

Keyword(s):

Mass Transfer ◽

Activated Carbon ◽

Surface Area ◽

Activated Carbons ◽

Carbon Surface ◽

Adsorptive Capacity ◽

Mineral Matter ◽

Transfer Coefficients ◽

Mass Transfer Coefficients ◽

Commercial Carbon

Abstract The present study investigated the relationship between the activated carbon surface area, as measured by the BET nitrogen adsorption method, and its adsorptive capacity. Aqueous solutions of phenol at pH 7 were used. The activated carbons were produced in the laboratory from raw and demineralized lignite. Adsorption experiments took place under equilibrium or kinetic conditions and the results were simulated by mathematical modelling. Freundlich and Langmuir models were used to describe equilibrium, while the Peel-Benedek non-equilibrium model was applied for the kinetic study. The results showed that for activated carbons produced from different starting materials, the adsorptive capacities could not be solely explained by their BET surface area. While laboratory-made activated carbons with a surface area of 300 m2/g demonstrated similar capacities under equilibrium, their kinetic behaviour was different. Activated carbon produced from raw lignite showed faster kinetics, due to wider porosity, which was facilitated by the mineral matter during activation. These results were in agreement with the mass transfer coefficients in macropores and micropores estimated by the Peel-Benedek model. Comparison of a laboratory-made activated carbon, with a surface area of 500m2/g, with a commercial activated carbon having twice the surface area showed that the maximum adsorptive capacity under equilibrium of the commercial carbon was only 35% higher than that of the lab-made carbon. Yet, the mass transfer coefficients of the commercial carbon were one to two orders of magnitude higher than those of the laboratory-produced carbon. Finally, the use of the qualitative D-R plots has been suggested to elucidate the porous structure of the activated carbons.

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Activated Carbons Tailored to Remove Different Pollutants from Gas Streams and from Solution

Adsorption Science & Technology ◽

10.1177/026361749701500106 ◽

1997 ◽

Vol 15 (1) ◽

pp. 59-68 ◽

Cited By ~ 9

Author(s):

Th. El-Nabarawy ◽

M.R. Mostafa ◽

A.M. Youssef

Keyword(s):

Carbon Dioxide ◽

Methylene Blue ◽

Activated Carbon ◽

Organic Pollutants ◽

Zinc Chloride ◽

Activated Carbons ◽

Carbon Surface ◽

Gas Streams ◽

Surface Areas ◽

Flow Techniques

Non-activated carbon ‘A’, physically-activated carbons P1–P4, zinc chloride-activated carbons Z1–Z4 and potassium sulphide-activated carbons K1–K4 were prepared from Maghara coal (Sinai, Egypt). The surface areas of these carbons were determined by investigating the adsorption of carbon dioxide at 298 K and of nitrogen at 77 K. The decolourization powers of the carbons were determined from methylene blue adsorption at 308 K. The adsorption of methanol, benzene, n-hexane, n-octane and α-pinene at 308 K was also determined using equilibrium and flow techniques. The removal of ammonia and phenol from water was investigated on some selected samples. The activated carbons showed high capacities towards the removal of organic pollutants from water and from gas streams via adsorption. Their capacity towards a particular pollutant depends on the method of activation and is related to the textural and/or the chemistry of the carbon surface.

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Production of Biologically Activated Carbon from Orange Peel and Landfill Leachate Subsequent Treatment Technology

Journal of Chemistry ◽

10.1155/2014/491912 ◽

2014 ◽

Vol 2014 ◽

pp. 1-9 ◽

Cited By ~ 23

Author(s):

Zhigang Xie ◽

Wei Guan ◽

Fangying Ji ◽

Zhongrong Song ◽

Yanling Zhao

Keyword(s):

Activated Carbon ◽

Active Carbon ◽

Three Dimensional ◽

Orange Peel ◽

Subsequent Treatment ◽

Raw Material ◽

Hydroxyl Group ◽

Treatment Technology ◽

Adsorption Method ◽

Enhanced Adsorption

In order to improve adsorption of macromolecular contaminants and promote the growth of microorganisms, active carbon for biological wastewater treatment or follow-up processing requires abundant mesopore and good biophile ability. In this experiment, biophile mesopore active carbon is produced in one-step activation with orange peel as raw material, and zinc chloride as activator, and the adsorption characteristics of orange peel active carbon is studied by static adsorption method. BET specific surface area and pore volume reached 1477 m2/g and 2.090 m3/g, respectively. The surface functional groups were examined by Fourier transform infrared spectroscopy (FT-IR). The surface of the as-prepared activated carbon contained hydroxyl group, carbonyl group, and methoxy group. The analysis based on X-ray diffraction spectrogram (XRD) and three-dimensional fluorescence spectrum indicated that the as-prepared activated carbon, with smaller microcrystalline diameter and microcrystalline thickness and enhanced reactivity, exhibited enhanced adsorption performance. This research has a deep influence in effectively controlling water pollution, improving area water quality, easing orange peel waste pollution, and promoting coordinated development among society, economy, and environment.

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Effect of Different Treatment on the Adsorption of p-Cresol by Activated Carbon

Eurasian Chemico-Technological Journal ◽

10.18321/ectj590 ◽

2017 ◽

Vol 5 (1) ◽

pp. 55 ◽

Cited By ~ 1

Author(s):

Sirous Nouri

Keyword(s):

Activated Carbon ◽

Adsorption Capacity ◽

Activated Carbons ◽

Molecular Form ◽

Carbon Surface ◽

Ionic Form ◽

Freundlich Model ◽

London Dispersion ◽

Carbon Change ◽

London Dispersion Forces

Adsorption of p-Cresol by three activated carbons (one untreated and two treated) was carried out at 301 K and at controlled pH conditions. By treating the activated carbon the PZC and adsorption capacity (Qmax) of carbon change. The adsorption capacity of each carbon, by using the homogenous Langmuir-Freundlich model, was found to comparing the effect of different treatment. At pH lower than pKa of p-cresol (molecular form), it was observed that the electron density of aromatic ring and also those of the carbon surface, are the main forces involved in the adsorption process, by affecting the extent of London dispersion forces. Treating by H2 increase the PZC and treating by H2SO4 decrease this factor. At higher pH (in ionic form), it was found that the electrostatic forces played a significant role on the extent of adsorption. In this condition the adsorption of the solute dependent on the concentration of anionic form of the solute. The effect of pH must be considered from its combined effects on the carbon surface and on the solute molecules. It was found that the uptake of the molecular form of the aromatic solute was dependent on the PZC of the carbon.

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