scholarly journals Triple activation (thermal-chemical-physical) in the development of an activated carbon from tobacco: characterizations and optimal conditions for Cd2+ and Pb2+ removal from waters

2020 ◽  
Vol 15 (4) ◽  
pp. 877-898 ◽  
Author(s):  
Jéssica Manfrin ◽  
Affonso Celso Gonçalves Jr ◽  
Daniel Schwantes ◽  
César Ricardo Teixeira Tarley ◽  
Andréia da Paz Schiller ◽  
...  
Keyword(s):  
Activated Carbon ◽  
Activated Carbons ◽  
Nonlinear Models ◽  
Carbon Surface ◽  
Heterogeneous Structures ◽  
Wide Ph Range ◽  
Ft Ir ◽  
Linear And Nonlinear ◽  
Ph Range ◽  
Cadmium And Lead

Abstract This research aimed to transform tobacco that originated from smuggled cigarettes into activated carbons, and to study its application in the remediation of water contaminated by cadmium and lead. For this, a triple activation was performed (thermal – chemical H3PO4 – physical CO2), resulting in the studied activated carbon (CT H3PO4 + CO2). The carbon was characterized by its chemical composition, pHPZC, Scanning Electron Microscopy (SEM), FT-IR, Brunauer-Emmett-Teller (BET), and BJH. The influence of the pH of Cd2+ and Pb2+ solutions, and the influence of the adsorbent dose, were studied. Isotherms were constructed by linear and nonlinear models of Langmuir, Freundlich, Sips, Dubinin-Radushkevich, and Temkin. CT H3PO4 + CO2 has carbonates, hydroxyls, carboxylic, and carbonic acids as surface functional groups. The triple activation caused changes in pHPZC (from 5.40 to 9.59). The SEM revealed a carbon surface full of irregular and heterogeneous structures, spongy aspect, with an estimated Specific Surface Area (SSA) increase of 395x and pore volume of 37x. The produced activated carbon has applicability over a wide pH range (3.00–7.00), with an ideal dose estimated at 4 g L−1 for greater efficiency in removing Cd2+ and Pb2. The linear and nonlinear models reveal that metal adsorption is predominantly physical and multi-layered, with a possible reuse in new sorption cycles.

Valorization of agricultural waste into activated carbons and its adsorption characteristics for heavy metals

2014 ◽  
Vol 4 (1) ◽  
Author(s):  
Bachar Koubaissy ◽  
Joumana Toufaily ◽  
Safaa Cheikh ◽  
Malak Hassan ◽  
Tayssir Hamieh
Keyword(s):  
Heavy Metals ◽  
Activated Carbon ◽  
Activated Carbons ◽  
Agricultural Waste ◽  
Carbon Surface ◽  
Chromium Vi ◽  
Xrd Study ◽  
Ft Ir ◽  
Pine Cones ◽  
Removal Fraction

AbstractActivated carbon derived from pine cones waste was prepared by carbonization at 450°C, activated by different activating agents: ZnCl 2, H 2 SO 4 and NaOH, and then pyrolyzed at 600°C. Adsorption of Cr VI and other heavy metals (Mn II, Fe II, Cu II) on activated carbons was investigated to evaluate the adsorption properties. Special attention was paid to the effects of carbon surface functionalities that were analyzed by FT-IR and zeta potential study. Moreover, XRD study of activated carbon was also carried out. Results had shown that activated carbon by NaOH was the best adsorbent for removal of chromium VI from wastewater. The solid-solution interaction was determined by analyzing the adsorption isotherms at room temperature at different pH. When pH is above 4, the removal fraction of Cr (VI) ions decreased with the increase of pH. The removal fraction of Cr (VI) ions decreased below pH 4. The preferable removal of Cu (II) over Mn(II) and Fe (II) could be due to its lower affinity to solvent.Pseudo-second order equation provided the better correlation for the adsorption kinetics data. Equilibrium isotherms were determined by Fowler-Guggenheim model.

scholarly journals The influence of active carbon contaminants on the ozonation mechanism interpretation

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Lilla Fijołek ◽  
Joanna Świetlik ◽  
Marcin Frankowski
Keyword(s):  
Activated Carbon ◽  
Active Carbon ◽  
Alkali Metals ◽  
Activated Carbons ◽  
Carbon Surface ◽  
Bulk Solution ◽  
Ozone Decomposition ◽  
Reaction Products ◽  
Treatment Technology ◽  
Carbon Impurities

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.

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

2013 ◽  
Vol 1505 ◽  
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.

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

1997 ◽  
Vol 15 (10) ◽  
pp. 803-814 ◽  
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.

SURFACE MODIFICATIONS OF ACTIVATED CARBON AND ITS IMPACT ON APPLICATION

2019 ◽  
Vol 26 (01) ◽  
pp. 1830006 ◽  
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.

scholarly journals Activated Carbon from Corncobs Doped with RuO2 as Biobased Electrode Material

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.

scholarly journals Synthesis of water-soluble chitosan for biomedical applications

2015 ◽  
Vol 18 (3) ◽  
pp. 170-180
Author(s):  
Anh Thi Tram Tu ◽  
Huy Thuc Ha
Keyword(s):  
Drug Delivery ◽  
Molecular Weight ◽  
Iron Oxide ◽  
Biomedical Applications ◽  
Drug Delivery Systems ◽  
Water Soluble ◽  
Oxide Nanoparticles ◽  
Wide Ph Range ◽  
Ft Ir ◽  
Ph Range

Highly deacetylated chitosan (CS) reacted with anhydride acetic (Ac2O) to produce chitosan with various degree of deacetylation (DDA) depending on the CS/Ac2O ratios. The structure of products was characterized by FT-IR, 1H NMR, 13C NMR, and the molecular weight was identified by GPC. The DDA of products decreases as the CS/Ac2O ratio increases. The products with less than 80 % DDA were soluble in water with a wide pH range. The water-soluble chitosan can be used in many biomedical applications such as manufacturing drug delivery systems or functionalized iron oxide nanoparticles.

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

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.

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

1995 ◽  
Vol 30 (2) ◽  
pp. 325-338 ◽  
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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