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22 pages, 5879 KiB

Open AccessArticle

A New Approach for Controlling Mesoporosity in Activated Carbon by the Consecutive Process of Air Oxidation, Thermal Destruction of Surface Functional Groups, and Carbon Activation (the OTA Method)

by Panuwat Lawtae and Chaiyot Tangsathitkulchai

Molecules 2021, 26(9), 2758; https://doi.org/10.3390/molecules26092758 - 7 May 2021

Cited by 23 | Viewed by 3725

Abstract

A new and simple method, based entirely on a physical approach, was proposed to produce activated carbon from longan fruit seed with controlled mesoporosity. This method, referred to as the OTA, consisted of three consecutive steps of (1) air oxidation of initial microporous [...] Read more.

A new and simple method, based entirely on a physical approach, was proposed to produce activated carbon from longan fruit seed with controlled mesoporosity. This method, referred to as the OTA, consisted of three consecutive steps of (1) air oxidation of initial microporous activated carbon of about 30% char burn-off to introduce oxygen surface functional groups, (2) the thermal destruction of the functional groups by heating the oxidized carbon in a nitrogen atmosphere at a high temperature to increase the surface reactivity due to increased surface defects by bond disruption, and (3) the final reactivation of the resulting carbon in carbon dioxide. The formation of mesopores was achieved through the enlargement of the original micropores after heat treatment via the CO₂ gasification, and at the same time new micropores were also produced, resulting in a larger increase in the percentage of mesopore volume and the total specific surface area, in comparison with the production of activated carbon by the conventional two-step activation method using the same activation time and temperature. For the activation temperatures of 850 and 900 °C and the activation time of up to 240 min, it was found that the porous properties of activated carbon increased with the increase in activation time and temperature for both preparation methods. A maximum volume of mesopores of 0.474 cm³/g, which accounts for 44.1% of the total pore volume, and a maximum BET surface area of 1773 m²/g was achieved using three cycles of the OTA method at the activation temperature of 850 °C and 60 min activation time for each preparation cycle. The two-step activation method yielded activated carbon with a maximum mesopore volume of 0.270 cm³/g (33.0% of total pore volume) and surface area of 1499 m²/g when the activation temperature of 900 °C and a comparable activation time of 240 min were employed. Production of activated carbon by the OTA method is superior to the two-step activation method for better and more precise control of mesopore development. Full article

(This article belongs to the Special Issue Porous Carbon Materials and Their Applications)

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20 pages, 10071 KiB

Open AccessArticle

Monte Carlo Simulation and Experimental Studies of CO₂, CH₄ and Their Mixture Capture in Porous Carbons

by Pakamas Kohmuean, Worapoj Inthomya, Atichat Wongkoblap and Chaiyot Tangsathitkulchai

Molecules 2021, 26(9), 2413; https://doi.org/10.3390/molecules26092413 - 21 Apr 2021

Cited by 16 | Viewed by 3743

Abstract

Adsorption of carbon dioxide and methane in porous activated carbon and carbon nanotube was studied experimentally and by Grand Canonical Monte Carlo (GCMC) simulation. A gravimetric analyzer was used to obtain the experimental data, while in the simulation we used graphitic slit pores [...] Read more.

Adsorption of carbon dioxide and methane in porous activated carbon and carbon nanotube was studied experimentally and by Grand Canonical Monte Carlo (GCMC) simulation. A gravimetric analyzer was used to obtain the experimental data, while in the simulation we used graphitic slit pores of various pore size to model activated carbon and a bundle of graphitic cylinders arranged hexagonally to model carbon nanotube. Carbon dioxide was modeled as a 3-center-Lennard-Jones (LJ) molecule with three fixed partial charges, while methane was modeled as a single LJ molecule. We have shown that the behavior of adsorption for both activated carbon and carbon nanotube is sensitive to pore width and the crossing of isotherms is observed because of the molecular packing, which favors commensurate packing for some pore sizes. Using the adsorption data of pure methane or carbon dioxide on activated carbon, we derived its pore size distribution (PSD), which was found to be in good agreement with the PSD obtained from the analysis of nitrogen adsorption data at 77 K. This derived PSD was used to describe isotherms at other temperatures as well as isotherms of mixture of carbon dioxide and methane in activated carbon and carbon nanotube at 273 and 300 K. Good agreement between the computed and experimental isotherm data was observed, thus justifying the use of a simple adsorption model. Full article

(This article belongs to the Special Issue Porous Carbon Materials and Their Applications)

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13 pages, 4092 KiB

Open AccessArticle

The Effects of Hydrophobicity and Textural Properties on Hexamethyldisiloxane Adsorption in Reduced Graphene Oxide Aerogels

by Xifeng Hou, Yanhui Zheng, Xiaolong Ma, Yuheng Liu and Zichuan Ma

Molecules 2021, 26(4), 1130; https://doi.org/10.3390/molecules26041130 - 20 Feb 2021

Cited by 20 | Viewed by 2541

Abstract

To expand the applications of graphene-based materials to biogas purification, a series of reduced graphene oxide aerogels (rGOAs) were prepared from industrial grade graphene oxide using a simple hydrothermal method. The influences of the hydrothermal preparation temperature on the textural properties, hydrophobicity and [...] Read more.

To expand the applications of graphene-based materials to biogas purification, a series of reduced graphene oxide aerogels (rGOAs) were prepared from industrial grade graphene oxide using a simple hydrothermal method. The influences of the hydrothermal preparation temperature on the textural properties, hydrophobicity and physisorption behavior of the rGOAs were investigated using a range of physical and spectroscopic techniques. The results showed that the rGOAs had a macro-porous three-dimensional network structure. Raising the hydrothermal treatment temperature reduced the number of oxygen-containing groups, whereas the specific surface area (S_BET), micropore volume (V_micro) and water contact angle values of the rGOAs all increased. The dynamic adsorption properties of the rGOAs towards hexamethyldisiloxane (L2) increased with increasing hydrothermal treatment temperature and the breakthrough adsorption capacity showed a significant linear association with S_BET, V_micro and contact angle. There was a significant negative association between the breakthrough time and inlet concentration of L2, and the relationship could be reliably predicted with a simple empirical formula. L2 adsorption also increased with decreasing bed temperature. Saturated rGOAs were readily regenerated by a brief heat-treatment at 100 °C. This study has demonstrated the potential of novel rGOA for applications using adsorbents to remove siloxanes from biogas. Full article

(This article belongs to the Special Issue Porous Carbon Materials and Their Applications)

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16 pages, 5003 KiB

Open AccessArticle

Interconnected Micro, Meso, and Macro Porous Activated Carbon from Bacterial Nanocellulose for Superior Adsorption Properties and Effective Catalytic Performance

by Arnon Khamkeaw, Tatdanai Asavamongkolkul, Tianpichet Perngyai, Bunjerd Jongsomjit and Muenduen Phisalaphong

Molecules 2020, 25(18), 4063; https://doi.org/10.3390/molecules25184063 - 5 Sep 2020

Cited by 26 | Viewed by 4202

Abstract

The porous carbon (bacterial cellulose (BC)-activated carbon (AC)(BA)) prepared via two-step activation of bacterial nanocellulose by treatments with potassium hydroxide (KOH) and then phosphoric acid (H₃PO₄) solutions showed superior adsorption properties and effective performance as catalyst support. BC-AC(BA) had [...] Read more.

The porous carbon (bacterial cellulose (BC)-activated carbon (AC)(BA)) prepared via two-step activation of bacterial nanocellulose by treatments with potassium hydroxide (KOH) and then phosphoric acid (H₃PO₄) solutions showed superior adsorption properties and effective performance as catalyst support. BC-AC(BA) had an open and interconnected multi-porous structure, consisting of micropores (0.23 cm³/g), mesopores (0.26 cm³/g), and macropores (4.40 cm³/g). The BET surface area and porosity were 833 m²/g and 91.2%, respectively. The methylene blue adsorption test demonstrated that BC-AC(BA) was superior in its mass transfer rate and adsorption capacities. Moreover, BC-AC(BA) modified by H₃PO₄ treatment showed a significant enhancement of catalytic performance for dehydration of ethanol. At the reaction temperature of 250–400 °C, 30P/BC-AC(BA) gave ethanol conversion at 88.4–100%, with ethylene selectivity of 82.6–100%, whereas, high selectivity for diethyl ether (DEE) at 75.2%, at ethanol conversion of 60.1%, was obtained at the reaction temperature of 200 °C. Full article

(This article belongs to the Special Issue Porous Carbon Materials and Their Applications)

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13 pages, 16438 KiB

Open AccessArticle

Biomass-Derived Porous Carbons Derived from Soybean Residues for High Performance Solid State Supercapacitors

by Hsiu-Ying Chung, Guan-Ting Pan, Zhong-Yun Hong, Chun-Tsung Hsu, Siewhui Chong, Thomas Chung-Kuang Yang and Chao-Ming Huang

Molecules 2020, 25(18), 4050; https://doi.org/10.3390/molecules25184050 - 4 Sep 2020

Cited by 27 | Viewed by 3766

Abstract

A series of heteroatom-containing porous carbons with high surface area and hierarchical porosity were successfully prepared by hydrothermal, chemical activation, and carbonization processes from soybean residues. The initial concentration of soybean residues has a significant impact on the textural and surface functional properties [...] Read more.

A series of heteroatom-containing porous carbons with high surface area and hierarchical porosity were successfully prepared by hydrothermal, chemical activation, and carbonization processes from soybean residues. The initial concentration of soybean residues has a significant impact on the textural and surface functional properties of the obtained biomass-derived porous carbons (BDPCs). SRAC5 sample with a BET surface area of 1945 m² g⁻¹ and a wide micro/mesopore size distribution, nitrogen content of 3.8 at %, and oxygen content of 15.8 at % presents the best electrochemical performance, reaching 489 F g⁻¹ at 1 A g⁻¹ in 6 M LiNO₃ aqueous solution. A solid-state symmetric supercapacitor (SSC) device delivers a specific capacitance of 123 F g⁻¹ at 1 A g⁻¹ and a high energy density of 68.2 Wh kg⁻¹ at a power density of 1 kW kg⁻¹ with a wide voltage window of 2.0 V and maintains good cycling stability of 89.9% capacitance retention at 2A g⁻¹ (over 5000 cycles). The outstanding electrochemical performances are ascribed to the synergistic effects of the high specific surface area, appropriate pore distribution, favorable heteroatom functional groups, and suitable electrolyte, which facilitates electrical double-layer and pseudocapacitive mechanisms for power and energy storage, respectively. Full article

(This article belongs to the Special Issue Porous Carbon Materials and Their Applications)

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16 pages, 3377 KiB

Open AccessArticle

Study on the Adsorption of CuFe₂O₄-Loaded Corncob Biochar for Pb(II)

by Tianci Zhao, Xiaolong Ma, Hao Cai, Zichuan Ma and Huifeng Liang

Molecules 2020, 25(15), 3456; https://doi.org/10.3390/molecules25153456 - 29 Jul 2020

Cited by 29 | Viewed by 3948

Abstract

A series of the magnetic CuFe₂O₄-loaded corncob biochar (CuFe₂O₄@CCBC) materials was obtained by combining the two-step impregnation of the corncob biochar with the pyrolysis of oxalate. CuFe₂O₄@CCBC and the pristine corncob [...] Read more.

A series of the magnetic CuFe₂O₄-loaded corncob biochar (CuFe₂O₄@CCBC) materials was obtained by combining the two-step impregnation of the corncob biochar with the pyrolysis of oxalate. CuFe₂O₄@CCBC and the pristine corncob biochar (CCBC) were characterized using XRD, SEM, VSM, BET, as well as pH_ZPC measurements. The results revealed that CuFe₂O₄ had a face-centered cubic crystalline phase and was homogeneously coated on the surface of CCBC. The as-prepared CuFe₂O₄@CCBC(5%) demonstrated a specific surface area of 74.98 m²·g⁻¹, saturation magnetization of 5.75 emu·g⁻¹ and pH_ZPC of 7.0. The adsorption dynamics and thermodynamic behavior of Pb(II) on CuFe₂O₄@CCBC and CCBC were investigated. The findings indicated that the pseudo-second kinetic and Langmuir equations suitably fitted the Pb(II) adsorption by CuFe₂O₄@CCBC or CCBC. At 30 °C and pH = 5.0, CuFe₂O₄@CCBC(5%) displayed an excellent performance in terms of the process rate and adsorption capacity towards Pb(II), for which the theoretical rate constant (k₂) and maximum adsorption capacity (q_m) were 7.68 × 10⁻³ g·mg^−1··min⁻¹ and 132.10 mg·g⁻¹ separately, which were obviously higher than those of CCBC (4.38 × 10⁻³ g·mg⁻¹·min⁻¹ and 15.66 mg·g⁻¹). The thermodynamic analyses exhibited that the adsorption reaction of the materials was endothermic and entropy-driven. The XPS and FTIR results revealed that the removal mechanism could be mainly attributed to the replacement of Pb²⁺ for H⁺ in Fe/Cu–OH and –COOH to form the inner surface complexes. Overall, the magnetic CuFe₂O₄-loaded biochar presents a high potential for use as an eco-friendly adsorbent to eliminate the heavy metals from the wastewater streams. Full article

(This article belongs to the Special Issue Porous Carbon Materials and Their Applications)

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11 pages, 2595 KiB

Open AccessArticle

Lignin Refinery Using Organosolv Process for Nanoporous Carbon Synthesis

by Imam Prasetyo, Puspita Rahayu Permatasari, William Teja Laksmana, Rochmadi Rochmadi, Won-Chun Oh and Teguh Ariyanto

Molecules 2020, 25(15), 3428; https://doi.org/10.3390/molecules25153428 - 28 Jul 2020

Cited by 11 | Viewed by 3167

Abstract

Porous carbon has been widely used for many applications e.g., adsorbents, catalysts, catalyst supports, energy storage and gas storage due to its outstanding properties. In this paper, characteristics of porous carbon prepared by carbonization of lignin from various biomasses are presented. Various biomasses, [...] Read more.

Porous carbon has been widely used for many applications e.g., adsorbents, catalysts, catalyst supports, energy storage and gas storage due to its outstanding properties. In this paper, characteristics of porous carbon prepared by carbonization of lignin from various biomasses are presented. Various biomasses, i.e., mangosteen peel, corncob and coconut shell, were processed using ethanol as an organosolv solvent. The obtained lignin was characterized using a Fourier transform infrared (FTIR) spectrophotometer and a viscosimeter to investigate the success of extraction and lignin properties. The results showed that high temperature is favorable for the extraction of lignin using the organosolv process. The FTIR spectra show the success of lignin extraction using the organosolv process because of its similarity to the standard lignin spectra. The carbonization process of lignin was performed at 600 and 850 °C to produce carbon from lignin, as well as to investigate the effect of temperature. A higher pyrolysis temperature will produce a porous carbon with a high specific surface area, but it will lower the yield of the produced carbon. At 850 °C temperature, the highest surface area up to 974 m²/g was achieved. Full article

(This article belongs to the Special Issue Porous Carbon Materials and Their Applications)

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18 pages, 4562 KiB

Open AccessArticle

Increased Recovery of Gold Thiosulfate Alkaline Solutions by Adding Thiol Groups in the Porous Structure of Activated Carbon

by Freddy R. Escobar-Ledesma, Carlos F. Aragón-Tobar, Patricio J. Espinoza-Montero and Ernesto de la Torre-Chauvin

Molecules 2020, 25(12), 2902; https://doi.org/10.3390/molecules25122902 - 24 Jun 2020

Cited by 12 | Viewed by 4151

Abstract

Thiosulfate leaching combined with ion-exchange resins is an innovative alternative for gold recovery. According to the properties of activated carbon, it could replace resins in the gold recovery process, improve efficiency, and reduce operating cost. In this research, the adsorption process of gold [...] Read more.

Thiosulfate leaching combined with ion-exchange resins is an innovative alternative for gold recovery. According to the properties of activated carbon, it could replace resins in the gold recovery process, improve efficiency, and reduce operating cost. In this research, the adsorption process of gold thiosulfate complex on thiol-modified activated carbon was studied. Thioglycolic acid (ATG) was impregnated in activated carbon, and its adsorption ability was tested with synthetic solutions of gold and sodium thiosulfate (Au 10 mg·L⁻¹, Na₂S₂O₃ 0.1 mol·L⁻¹, pH = 10.0). Carbon was characterized by infrared spectroscopy, SEM-EDS, PZC titration, hardness number measures, and proximal analysis. Synthetic solutions were also characterized by UV-vis spectroscopy and cyclic voltammetry. The percentage of volatile material increased from 10.0 to 13.9% due to the impregnation process of ATG. Infrared spectra show characteristic bands of C-H, S-H, and C-S bonds. In the adsorption tests, the ATG-impregnated carbon achieved 91% of gold recovery, while the same amount of ATG in the liquid phase stirred with unmodified activated carbon reached 90% of gold recovery. The 44.9% of gold recovered with activated carbon impregnated with ATG was eluted with sodium cyanide ([NaCN] = 0.2 mol·L⁻¹; [NaOH] = 0.25 mol·L⁻¹; [CH₃CH₂OH] = 30% V/V; pH = 12.0; t = 24 h). These results suggest the gold transferred from the thiosulfate complex to a new gold thiolate complex. Full article

(This article belongs to the Special Issue Porous Carbon Materials and Their Applications)

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18 pages, 3968 KiB

Open AccessArticle

Reactivation Process of Activated Carbons: Effect on the Mechanical and Adsorptive Properties

by Rita B. Cevallos Toledo, Carlos F. Aragón-Tobar, Sebastián Gámez and Ernesto de la Torre

Molecules 2020, 25(7), 1681; https://doi.org/10.3390/molecules25071681 - 7 Apr 2020

Cited by 34 | Viewed by 5153

Abstract

Carbon reactivation is a strategy to reduce waste and cost in many industrial processes, for example, effluent treatment, food industry, and hydrometallurgy. In this work, the effect of physical and chemical reactivation of granular activated carbon (AC) was studied. Spent activated carbon (SAC) [...] Read more.

Carbon reactivation is a strategy to reduce waste and cost in many industrial processes, for example, effluent treatment, food industry, and hydrometallurgy. In this work, the effect of physical and chemical reactivation of granular activated carbon (AC) was studied. Spent activated carbon (SAC) was obtained from a carbon in pulp (CIP) leaching process for gold extraction. Chemical and physical reactivations were evaluated using several acid-wash procedures (HCl, HNO₃, H₂SO₄) and thermal treatment (650–950 °C) methods, respectively. The effect of the reactivation processes on the mechanical properties was evaluated determining ball pan hardness and normal abrasion in pulp resistance. The effect on the adsorptive properties was evaluated via the iodine number, the gold adsorption value (k expressed in mg Au/g AC), and Brunauer–Emmett–Teller (BET) surface area. Initial characterization of the SAC showed an iodine number of 734 mg I₂/g AC, a k value of 1.37 mg Au/g AC, and a BET surface area of 869 m²/g. The best reactivation results of the SAC were achieved via acid washing with HNO₃ at 20% v/v and 50 °C over 30 min, and a subsequent thermal reactivation at 850 °C over 1 h. The final reactivated carbon had an iodine number of 1199 mg I₂/g AC, a k value of 14.9 mg Au/g AC, and a BET surface area of 1079 m²/g. Acid wash prior to thermal treatment was critical to reactivate the SAC. The reactivation process had a minor impact (<1% change) on the mechanical properties of the AC. Full article

(This article belongs to the Special Issue Porous Carbon Materials and Their Applications)

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11 pages, 4200 KiB

Open AccessArticle

Fe_1−xS Modified TiO₂ NPs Embedded Carbon Nanofiber Composite via Electrospinning: A Potential Electrode Material for Supercapacitors

by Bishweshwar Pant, Hem Raj Pant and Mira Park

Molecules 2020, 25(5), 1075; https://doi.org/10.3390/molecules25051075 - 27 Feb 2020

Cited by 28 | Viewed by 3671

Abstract

Fe_1−xS-TiO₂ nanoparticles embedded carbon nanofibers (Fe_1−xS-TiO₂/CNFs) composite as a supercapacitor electrode material has been reported in the present work. The Fe_1−xS-TiO₂/CNFs composite was fabricated by electrospinning technique followed by carbonization under argon [...] Read more.

Fe_1−xS-TiO₂ nanoparticles embedded carbon nanofibers (Fe_1−xS-TiO₂/CNFs) composite as a supercapacitor electrode material has been reported in the present work. The Fe_1−xS-TiO₂/CNFs composite was fabricated by electrospinning technique followed by carbonization under argon atmosphere and characterized by the state-of-art techniques. The electrochemical studies were carried out in a 2 M KOH electrolyte solution. The synthesized material showed a specific capacitance value of 138 F/g at the current density of 1 A/g. Further, the capacitance retention was about 83%. The obtained results indicate that the Fe_1−xS-TiO₂/CNFs composite can be recognized as electrode material in supercapacitor. Full article

(This article belongs to the Special Issue Porous Carbon Materials and Their Applications)

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16 pages, 4084 KiB

Open AccessArticle

Soft-Templating of Sulfur and Iron Dual-Doped Mesoporous Carbons: Lead Adsorption in Mixtures

by Dipendu Saha, Connelly P. Richards, Robert G. Haines, Nicholas D. D’Alessandro, Madeleine J. Kienbaum and Christian A. Griffaton

Molecules 2020, 25(2), 403; https://doi.org/10.3390/molecules25020403 - 18 Jan 2020

Cited by 11 | Viewed by 2687

Abstract

Lead pollution in drinking water is one of the most common problems worldwide. In this research, sulfur and iron dual-doped mesoporous carbons are synthesized by soft-templating with sulfur content 4.4–6.1 atom% and iron content 7.8–9 atom%. Sulfur functionalities of the carbons are expected [...] Read more.

Lead pollution in drinking water is one of the most common problems worldwide. In this research, sulfur and iron dual-doped mesoporous carbons are synthesized by soft-templating with sulfur content 4.4–6.1 atom% and iron content 7.8–9 atom%. Sulfur functionalities of the carbons are expected to enhance the affinity of the carbon toward lead whereas iron content is expected to separate the carbon from water owing to its magnetic properties. All the carbons were characterized by pore textural properties, x-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and energy dispersive x-ray (EDX). In order to study the Pb(II) removal efficiently of this carbon in competitive mode and to mimic the real-world use, one additional heavy-metal, including Cr(III), and four other commonly occurring metals—Na(I), K(I), Ca(II) and Fe (III)—are added with lead prior to adsorption experiments. It was observed that Pb(II) adsorption capacity of this carbon was not influenced by the presence of other metals. A highly elevated concentration of Na(I), K(I), Ca(II) and Fe(III) in the eluting solution compared to the initial dose suggested possible leaching of those metals from other salts as impurities, water source or even from the carbon itself, although the XPS analysis of the carbon confirmed negligible adsorption of those metals in carbon. From the equilibrium and kinetic data of adsorption, few parameters have been calculated, including distribution coefficient, diffusive time constant and pseudosecond order rate constant. The overall results suggest that these iron and sulfur dual-doped mesoporous carbons can serve as potential adsorbents for removal of lead from drinking water in the presence of other competing metals. Full article

(This article belongs to the Special Issue Porous Carbon Materials and Their Applications)

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13 pages, 3042 KiB

Open AccessArticle

Blotting Paper-Derived Activated Porous Carbon/Reduced Graphene Oxide Composite Electrodes for Supercapacitor Applications

by Qinting Jiang, Dandan Liu, Bo Liu, Tong Zhou and Jin Zhou

Molecules 2019, 24(24), 4625; https://doi.org/10.3390/molecules24244625 - 17 Dec 2019

Cited by 17 | Viewed by 3723

Abstract

A facile strategy, engineered for low-cost mass production, to synthesize biomass-derived activated carbon/reduced graphene oxide composite electrodes (GBPCs) by one-pot carbonization of blotting papers containing graphene oxide (GO) and zinc chloride (ZnCl₂) was proposed. Benefitting from the water absorption characteristic of [...] Read more.

A facile strategy, engineered for low-cost mass production, to synthesize biomass-derived activated carbon/reduced graphene oxide composite electrodes (GBPCs) by one-pot carbonization of blotting papers containing graphene oxide (GO) and zinc chloride (ZnCl₂) was proposed. Benefitting from the water absorption characteristic of blotting papers in which the voids between the celluloses can easily absorb the GO/ZnCl₂ solution, the chemical activation and reduction of GO can synchronously achieve via one-step carbonization process. As a result, the GBPCs deliver a large specific surface area to accumulate charge. Simultaneously, it provides high conductivity for electron transfer. The symmetric supercapacitor assembled with the optimal GBPCs in 6 M KOH electrolyte exhibits an excellent specific capacitance of 204 F g⁻¹ (0.2 A g⁻¹), outstanding rate capability of 100 F g⁻¹ (20 A g⁻¹). Meanwhile, it still keeps 90% of the initial specific capacitance over 10,000 cycles. The readily available raw material, effective chemical activation, simple rGO additive, and resulting electrochemical properties hold out the promise of hope to achieve low-cost, green, and large-scale production of practical activated carbon composite materials for high-efficiency energy storage applications. Full article

(This article belongs to the Special Issue Porous Carbon Materials and Their Applications)

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13 pages, 1795 KiB

Open AccessArticle

Parabens Adsorption onto Activated Carbon: Relation with Chemical and Structural Properties

by Astrid Roxanna Moreno-Marenco, Liliana Giraldo and Juan Carlos Moreno-Piraján

Molecules 2019, 24(23), 4313; https://doi.org/10.3390/molecules24234313 - 26 Nov 2019

Cited by 20 | Viewed by 3835

Abstract

Parabens (alkyl-p-hidroxybenzoates) are antimicrobial preservatives used in personal care products, classified as an endocrine disruptor, so they are considered emerging contaminants. A raw version of activated carbons obtained from African palm shell (Elaeis guineensis) modified chemically by impregnation with salts of CaCl₂ [...] Read more.

Parabens (alkyl-p-hidroxybenzoates) are antimicrobial preservatives used in personal care products, classified as an endocrine disruptor, so they are considered emerging contaminants. A raw version of activated carbons obtained from African palm shell (Elaeis guineensis) modified chemically by impregnation with salts of CaCl₂ (GC2), MgCl₂ (GM2) and Cu(NO₃)₂ (GCu2) at 2% wt/v and carbonized in CO₂ atmosphere at 1173 K was prepared. The process of adsorption of methyl (MePB) and ethylparaben (EtPB) from aqueous solution on the activated carbons at 18 °C was studied and related to the interactions between the adsorbate and the adsorbent, which can be quantified through the determination of immersion enthalpies in aqueous solutions of corresponding paraben, showing the lowest-value carbon GM2, which has a surface area of 608 m² × g⁻¹, while the highest values correspond to the activated carbon GCu2, with a surface area of 896 m² × g⁻¹ and the highest content of surface acid sites (0.42 mmol × g⁻¹), such as lactonic and phenolic compounds, which indicates that the adsorbate–adsorbent interactions are favored by the presence of these, with interaction enthalpies that vary between 5.72 and 51.95 J × g⁻¹ for MePB adsorption and 1.24 and 52.38 J × g⁻¹ for EtPB adsorption showing that the process is endothermic. Full article

(This article belongs to the Special Issue Porous Carbon Materials and Their Applications)

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14 pages, 14113 KiB

Open AccessArticle

Nitrogen-Doped Hierarchical Meso/Microporous Carbon from Bamboo Fungus for Symmetric Supercapacitor Applications

by Zhanghua Zou, Yu Lei, Yingming Li, Yanhua Zhang and Wei Xiao

Molecules 2019, 24(20), 3677; https://doi.org/10.3390/molecules24203677 - 12 Oct 2019

Cited by 43 | Viewed by 4005

Abstract

We report the synthesis of nitrogen-doped hierarchical meso/microporous carbon using renewable biomass bamboo fungus as precursor via two-step pyrolysis processes. It is found that the developed porous carbon (NHPC-800) features honeycomb-like cellular framework with well-developed porosity, huge specific surface area (1708 m² [...] Read more.

We report the synthesis of nitrogen-doped hierarchical meso/microporous carbon using renewable biomass bamboo fungus as precursor via two-step pyrolysis processes. It is found that the developed porous carbon (NHPC-800) features honeycomb-like cellular framework with well-developed porosity, huge specific surface area (1708 m² g⁻¹), appropriate nitrogen-doping level (3.2 at.%) and high mesopore percentage (25.5%), which are responsible for its remarkable supercapacitive performances. Electrochemical tests suggest that the NHPC-800 electrode offers the largest specific capacitance of 228 F g⁻¹, asplendid rate capability and stable electrochemical behaviors in a traditional three-electrode system. Additionally, asymmetric supercapacitor device is built based on this product as well. An individual as-assembled supercapacitor of NHPC-800//NHPC-800 delivers the maximum energy density of 4.3 Wh kg⁻¹; retains the majority of capacitanceat large current densities; and shows terrific cycling durability with negligible capacitance drop after long-term charge/discharge for beyond 10,000 cycles even at a high current density of 10 A g⁻¹. These excellent supercapacitive properties of NHPC-800 in both three- and two-electrode setups outperform those of lots of biomass-derived porous carbons and thus make it a perspective candidate for producing cost-effective and high-performance supercapacitors Full article

(This article belongs to the Special Issue Porous Carbon Materials and Their Applications)

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47 pages, 12273 KiB

Open AccessReview

Activated Carbons and Their Evaluation in Electric Double Layer Capacitors

by Krzysztof Kierzek and Grażyna Gryglewicz

Molecules 2020, 25(18), 4255; https://doi.org/10.3390/molecules25184255 - 16 Sep 2020

Cited by 47 | Viewed by 7283

Abstract

This review presents a summary of the manufacturing of activated carbons (ACs) as electrode materials for electric double layer capacitors. Commonly used techniques of open and closed porosity determination (gas adsorption, immersion calorimetry, X-ray and neutrons scattering) were briefly described. AC production methods [...] Read more.

This review presents a summary of the manufacturing of activated carbons (ACs) as electrode materials for electric double layer capacitors. Commonly used techniques of open and closed porosity determination (gas adsorption, immersion calorimetry, X-ray and neutrons scattering) were briefly described. AC production methods (laboratory and industrial) were detailed presented with the stress on advantages and drawbacks of each ones in the field of electrode materials of supercapacitor. We discussed all general parameters of the activation process and their influence on the production efficiency and the porous structure of ACs. We showed that porosity development of ACs is not the only factor influencing capacity properties. The role of pore size distribution, raw material origin, final carbon structure ordering, particles morphology and purity must be also taken into account. The impact of surface chemistry of AC was considered not only in the context of pseudocapacity but also other important factors, such as inter-particle conductivity, maximal operating voltage window and long-term stability. Full article

(This article belongs to the Special Issue Porous Carbon Materials and Their Applications)

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