Activated Carbon Materials Research Articles

Activated carbon cellulose acetate based as effective adsorbent of contaminants from water

Various methods can be employed to remove pollutants from wastewater. Among these, adsorption using activated carbon materials has proven effective. This work proposes the use of a hazardous waste made from a semisynthetic polymer, cellulose acetate from cigarette butts, as raw material to produce activated carbons (AC). Four adsorbents were prepared from dirty and clean cigarette butts; two chemically activated carbons using phosphoric acid and two physically activated carbons using water vapor at 623 K. The carbons were characterized using FTIR, SEM, Nitrogen adsorption, and their points of zero charge. AC produced showed high potential as adsorbents for cleaning hazardous dyes from aqueous solutions. Adsorption isotherms were constructed for the textile dyes on the carbons, and these data were treated using Langmuir's equation to quantitatively describe the adsorption process. The adsorption of dyes with an initial concentration of 300 mg dm−3 showed adsorption percentages closed to the 100% for cationic dyes, while these oscillated between 40% and 100% for anionic dyes with the four activated carbons. The highest values of monolayer capacity (am) were achieved with the activated carbon prepared from cellulose acetate without prior treatment. Monolayer capacity with values ranging from 185 to 277 mg g−1 for cationic dyes and 126–178 mg g−1 for anionic dyes were obtained. Therefore, any waste of cellulose acetate can be used to obtain activated carbons with excellent adsorption capacities for dyes Methylene Blue, Crystal Violet, Malachite Green, Sirius Turquoise and Fluorescein.

Cocoa husk as precursor of carbonaceous materials for supercapacitors electrodes

Activated carbon materials are widely used as high-performance electrodes for supercapacitors because they allow improving the electrochemical performance of these devices. The development of high surface areas and high porosity contributes to the energy storage by double electric layer, whereas the content of different functional groups on their surface to the pseudocapacitive storage. In addition, they can be obtained from lignocellulosic wastes providing a novel and economic perspective for the development of carbon-based electrodes. In this work, activated carbons were synthesized from cocoa husks using KOH as activating agent. The materials were obtained at three impregnation ratios (1:1, 3:1, 5:1) and three carbonization temperatures (500, 650, and 800 °C), optimizing the best conditions to obtain materials with high surface areas and porosity together with surface functional groups to improve energy storage. The results show that the 800 °C synthesized material with 3:1 impregnation ratio presents a capacitance of 120 F/g at 1 A/g, with a retention capacity of 93 % after 12,000 cycles, being the best electrochemical behavior among the carbons prepared. This is attributed to the adequate micro-mesoporosity, content of surface oxygenated functional groups and high surface area (1444 m2/g).

Time-dependent synthesis of tungsten disulfide for flexible supercapacitors

Tungsten disulfide (WS2) with various nanostructures was synthesized for times ranging from 6 to 72 h, using a simple and easy hydrothermal technique, for high-performance supercapacitor applications. The synthesized WS2 for 24 h (WS2–24), among other synthesized WS2, exhibited flower-like structures, composed of numerous nanosheets, demonstrating superior electrochemical properties in terms of electrochemical surface area, charge transfer resistance, specific capacitance, and rate capability. In addition, WS2–24 was coated on a flexible activated carbon cloth substrate to make flexible electrodes and assemble a flexible symmetric supercapacitor with a gel electrolyte. The flexible supercapacitor exhibited a specific capacitance of 262.5 F g−1 at 1 A g−1 with an energy density of 23.6 Wh kg−1 and a power density of 802 W kg−1. It also showed excellent capacitance retention of 94.5 % and a Coulombic efficiency of 86.4 % after 5000 cycles. The remarkable electrochemical properties of the synthesized WS2 materials highlight them as highly effective active materials for high-performance supercapacitor electrodes.

Activated carbon cloth versus silver-based dressings in a population with diabetic foot ulcer: a randomised controlled trial.

Activated carbon cloth (ACC), known as Zorflex dressing, has emerged as an innovative approach in managing bacterial infection in diabetic foot ulcer (DFU) treatment. This pilot study was undertaken to determine the efficacy of Zorflex ACC dressing (Chemviron Carbon Cloth Division, UK) compared to standard silver-based dressing on DFUs. An open label, comparative, randomised controlled trial enrolling patients who attended the diabetic foot clinic was conducted between August 2022 and August 2023. The primary endpoint was a difference of 20% in wound area reduction with the ACC dressing compared to silver-based dressing within eight weeks. The secondary endpoints were proportion of complete healing, time to healing and adverse events. The cohort comprised 40 patients. The mean wound reduction percentage at 8 weeks for patients in the ACC arm was 85.40±16.00% compared with 65.08±16.36% in the silver-based dressing arm. Complete healing was observed in six of 20 patients in the ACC arm compared to two of 20 in the silver-based dressing arm. These data suggest that the ACC dressing promotes better ulcer healing in DFU patients than the silver-based dressing.

Morphology reconstruction of nickel cobalt layered double hydroxides induced by electrolyte concentrations triggers high performance of supercapattery storage

AbstractNickel cobalt layered double hydroxides (NiCo LDHs) have emerged as ideal electrode materials for supercapattery due to their high specific surface area and excellent cycling stability. Morphology control plays a unique role in regulating the performance of the NiCo LDHs. Herein, the morphology of NiCo‐LDHs electrode is optimized for enhancing energy storage by a simple activation process with different concentrations of the electrolyte. During the activation process, electrochemical morphology reconstruction occurs on the electrode surface. With a 2 m KOH electrolyte, the NiCo‐LDH electrode transforms from nanosheets to nanoflower, which aids in reducing the distance of ion transport. The reconstructed NiCo‐LDH exhibits an ultra‐high specific capacity of 2809 C g−1 at a current density of 1 A g−1, outperforming most of NiCo LDHs. At a high current density of 10 A g−1, the capacity retention rate remains above 72.7% after 3000 cycles. An asymmetric supercapacitor is fabricated with activated carbon material as the negative electrode, the energy density is 36 Wh kg−1 at the power density of 732 W kg−1. The strategy proposed in the study, which involves concentration‐controlled morphology optimization for energy storage enhancement, holds great practical significance for the field of supercapatteries.

Removal of Heavy Metal Ions (Pb2+, Co2+, and Cd2+) by Activated Carbon from Cypress Fruit: An Investigation of Kinetics, Thermodynamics, and Isotherms

In this study, activated carbon cloth (ACC) derived from cypress fruit was employed to investigate the adsorption of Pb2+, Cd2+, and Co2+ from synthetic aqueous systems. The correlation between adsorption features (pH, adsorbent dosage, temperature, initial ion concentration, and contact time) and adsorbent removal efficiency was investigated. Analysis by FT-IR, SEM, and EDS was employed to confirm the adsorption of metal ions onto the ACC. Results revealed the best adsorption efficiencies for heavy metal ions were attained at pH = 7, 11, 6; the adsorbent dosage of 0.06, 0.08, and 0.04 g for Pb2+, Cd2+, and Co2+, respectively; the ion initial concentration of 50 mg·L−1 for Pb2+ and 70 mg·L−1 for both Co2+ and Cd2+; and contact time of 90 minutes for both Pb2+ and Co2+ and 120 minutes for Cd2+. Kinetic studies exposed the second-order adsorption of all aforementioned heavy metal ions. Additionally, the equilibrium data were fitted by Langmuir and Freundlich’s isotherms, while the former performed better than the latter. The maximum adsorption capacity values for Pb2+, Co2+, and Cd2+ were attained to 81.87, 55.30, and 117.3 mg·g−1, respectively. Considering the thermodynamic data, the studied processes were exothermic and spontaneous.

Detoxification of toxic nerve agent sarin utilizing cupric oxide functionalized activated carbon fabric composite for advanced NBC Protective Clothing

ABSTRACT This investigation delves into the development of cupric oxide functionalized activated carbon fabrics (ACF@CuO) as a filter material for self-decontaminating protective clothing designed to counter chemical warfare agents (CWAs). Three variants of samples were developed by controlling functionalization levels (7.5%, 13.0%, 16.0% w/w) through optimized precursor concentrations, integrating CuO particles onto ACF surfaces. Comprehensive analysis using techniques like FTIR, BET surface area, SEM, EDX, STEM, XRD, TGA, and XPS explored the material’s properties. The studies concentrated on evaluating the performance through kinetic studies of self-detoxification of CWA Sarin (GB) using developed ACF@CuO materials analyzed by Gas Chromatography-Mass Spectrometry (GC-MS). ACF@CuO with 16% w/w functionalization exhibited superior self-decontamination against GB, achieving 92.87% efficiency within 18 hours, in contrast to 26.55% for ACF alone. Additionally, materials were tested for tensile strength, air-permeability, and Sulfur Mustard breakthrough time (HDBTT) as per IS 17377:2020 standard. The material with 13% w/w functionalization emerged as the recommended filter layer for CWA protective clothing designed for defense and civilian safety applications. The significant improvements in the self-decontamination efficiency of the material were attributed to the synergistic effects of ACF’s adsorption capabilities combined with the decontamination properties of CuO rod-shaped crystals embedded in the surface of ACF.

Nitrogen-phosphorus dual-doped auricularia auricula porous carbon as host for Li-S battery.

A nitrogen-phosphorus dual-doped porous spore carbon (NP-PSC) positive electrode matrix was prepared using native auricularia auricula as solid medium based on the principle of biomass rot. Yeast was introduce and cultured by the auricularia auricula solid medium. The freeze-drying and carbonization activation processes made the materials present a three-dimensional porous spore carbon aerogel properties. Yeast fermentation transformed auricularia auricula from blocky structure to porous structure and introduced nitrogen-phosphorus dual-doping. The physical and chemical properties of the prepared materials were characterized in detail. Electrochemical performance of NP-PSC in Li-S batteries was systematically investigated. Porous structure and heteroatom-doping improved the electrochemical performance, which is much superior to conventional activated carbon materials.

The production of a novel adsorbent from forest waste (Platanus orientalis L.) for dye adsorption: Adsorption process optimization and experimental design

In the study, a novel activated carbon material was produced using forest waste commonly found in nature. The activation was completed by modifying the surface of the material with H3PO4. Using this adsorbent material, we investigated the adsorption of the hazardous dyestuff, methylene blue, from the water environment. The adsorbent was characterized using BET, SEM, and FT-IR analyses. The characterization processes revealed that the adsorbent has a wealth of functional groups and many cavities and protrusions on its surface. Moreover, according to the BET analysis result, it was observed that it is an adsorbent with a high surface area (876.01 m2 g−1). Kinetic, equilibrium and thermodynamic studies have been conducted to fully understand the nature of methylene blue adsorption. The pseudo-second order kinetic model best represents the adsorption process data, and the Langmuir isotherm aligns with the equilibrium data. According to the Langmuir isotherm data, the maximum adsorption capacity (qmax) was determined to be 198.01 mg g−1. The thermodynamic results showed that the process of adsorption of methylene blue on various surfaces is spontaneous and occurs via physisorption. Additionally, in addition, the effects of the parameters (adsorbent dose, time, and concentration) determined for the methylene blue adsorption process were optimized using the surface response method. Activated carbon from plane tree fruits (Platanus orientalis L.) has the potential to be a novel adsorbent due to its unique surface morphology and strong adsorption capabilities.

Porous carbon prepared by thermal dissolution of coal and biomass for high-performance supercapacitors

Porous carbon materials have been considered a kind of promising materials for supercapacitors due to high specific surface area and excellent electronic conductivity. Soluble portions (SPs) acquired from thermal dissolution of carbon-based raw materials have been used as the carbon source for hierarchical porous carbons (HPC). In this work, mixtures of rice straw and coal at different mass ratios were selected as the raw materials for co-thermal dissolution to obtain SPX. The variation of soluble proportions and subsequent impacts on the electrochemical properties of HPCX were investigated. During thermal dissolution, the addition of rice straw increased the content of nitrogen-containing compounds in SPX. Therefore, the specific capacitance of HPC1/4 is 355 F/g. The specific capacitance of activated carbon material without rice straw is only 299 F/g. The relationship between the molecular characteristics of carbon source and the performance of supercapacitors has been determined. In addition to oxygen-containing compounds, the presence of nitrogen-containing compounds can also lead to a higher electrochemical property for porous carbon materials.

Enhancing Electrochemical Properties of Walnut Shell Activated Carbon with Embedded MnO Clusters for Supercapacitor Applications

AbstractActivated carbon (AC) materials from renewable sources are widely used in electrochemical applications due to their well‐known high surface area. However, their application as electrode material in double‐layer electrochemical devices may be limited due to their relatively low electrical conductivity and lightweight. To overcome these limitations, the incorporation of pseudocapacitance metal oxide nanoparticles is an optimum approach. These nanoparticles can provide a second energy storage mechanism to the composite, mitigating the loss of surface area associated with their incorporation. As a result, the composite material is endowed with increased conductivity and higher density, making it more suitable for practical implementation in real devices. In this study, we have incorporated a fine dispersion of 1 % of MnO clusters into a highly porous activated carbon synthesized from walnut shells (WAC). The high‐resolution electron microscopy studies, combined with their related analytical techniques, allow us to determine the presence of the cluster within the matrix carbon precisely. The resulting MnO@WAC composite demonstrated significantly improved capacitive behavior compared with the WAC material, with increased volumetric capacitance and higher charge retention at higher current densities. The composite‘s electrochemical performance suggests its potential as a promising electrode material for supercapacitors, addressing drawbacks associated with traditional AC materials.

Pore-structure control of porous carbon electrode materials and energy-storage performance in water-in-salt electrolytes

The pore structure of carbon-based materials and the voltage window of the electrolyte are two key factors affecting the energy density of carbon-based supercapacitors (SCs). In this paper, activated carbon materials of different pore sizes is successfully synthesized by chemical activation method by adjusting the mass ratio of ZnCl2 to sucrose, and successfully applied to construct SCs based on different electrolyte systems. As the specific surface area of the prepared porous carbon materials shows a tendency to increase and then decrease, reaching a maximum in the presence of micropores. Further summarizing the constitutive relationship between pore structure-electrochemical performance in the high-concentration electrolyte system, it is found that the normalized specific capacity is larger at smaller pore sizes, and with the increase of mesoporous proportion, the normalized specific capacity decreases and tends to be stable. In addition, the different strengths of solvation of anions and cations in the electrolyte, with the cations contributing more to the contrast, and the presence of mesopores providing ion transport channels to improve the efficiency of ion transport in porous materials, which provide directions for designing a suitable pore structure for highly concentrated salt electrolytes, as well as another way of optimizing the properties of carbon-based materials for SCs.

A review on agrowaste based activated carbons for pollutant removal in wastewater systems

Environmental pollution from chemicals utilized in manufacturing, pharmaceuticals, and chemical process industries is of serious concern nowadays due to the contamination that ensues when these chemicals are discharged into water bodies. Activated carbon adsorption provides an efficient and economically viable means for mitigation of toxic chemicals (i.e., heavy metals, dyes, pharmaceutics, and antibiotics). However, the exorbitant cost of commercial activated carbons has resulted in the search for low-cost alternatives for the treatment of contaminated effluents. An exhaustive literature survey in this area is necessary to know the extent of work done in this area and seek out the gaps that future research will provide answers to. In this review, various works on activated carbon utilization, batch adsorption, fixed-bed adsorption (experimental and numerical studies) are summarized. This review elucidates the different kinetic and isotherm models of agrowastes-derived activated carbon materials in context with pollutants (dyes, heavy metals, pharmaceuticals, miscellaneous adsorbates) removal through batch and column methods. In addition, fixed-bed column adsorption/regeneration methods using various activated carbons derived from agrowastes are discussed. Among these methods, heavy metal adsorption from aqueous solutions by the activated carbons is the most efficient. The deployment of mathematical and machine learning approaches (ANN and novel GMDH algorithms) in optimization of batch and continuous adsorption processes are also highlighted. Numerical simulation of fixed-column adsorption systems for more improved industrial-scale column designs is described. Conclusions and future challenges of chemicals removal from polluted wastewater utilizing agrowaste-derived activated carbons are also presented.

Investigation of the Desalination Capacity of Activated Carbon Materials from Water Hyacinth (<i>Eichhornia crassipes</i>) Stems

To reduce the hazards brought by water hyacinth, many applications of water hyacinth have been studied and continuously expanded. The large biomass of water hyacinth is applied in many fields such as for wastewater treatment, wastewater purification, biological raw material sources, animal feed production, medicine, antioxidants, agriculture, and household appliances. This research investigates the desalination capacity of freshwater hyacinths, raw materials from water hyacinths, biochar, and activated carbon materials from water hyacinth stems. Results have shown that the suitable temperature for charring fresh water hyacinth is 420 °C. The activated carbon from the water hyacinth stems with a BET surface area of 200.4 ± 1.9 m²/g can be desalinated under the conditions of 0.4 g of activated carbon mass, 15 min of reaction time, 2.0 ppt of salt concentration, and at neutral pH. In contrast, raw materials from water hyacinths and biochar were unable to desalinate. This study evaluates the desalination ability of the activated carbon material of water hyacinth.

Critical Roles of pH and Activated Carbon on the Speciation and Performance of an Archetypal Organometallic Complex for Aqueous Redox Flow Batteries.

A lack of suitable high-potential catholytes hinders the development of aqueous redox flow batteries (RFBs) for large-scale energy storage. Hydrolysis of the charged (oxidized) catholyte typically occurs when its redox potential approaches that of water, with a negative impact on battery performance. Here, we elucidate and address such behavior for a representative iron-based organometallic complex, showing that the associated voltage and capacity losses can be curtailed by several simple means. We discovered that addition of activated carbon cloth (ACC) to the reservoir of low-cost, high-potential [Fe(bpy)3]2+/3+ catholyte-limited aqueous redox flow batteries extends their lifetime and boosts discharge voltage─two typically orthogonal performance metrics. Similar effects are observed when the catholyte's graphite felt electrode is electrochemically oxidized (overcharged) and by modifying the catholyte solution's pH, which was monitored in situ for all flow batteries. Modulation of solution pH alters hydrolytic speciation of the charged catholyte from the typical dimeric species μ-O-[FeIII(bpy)2(H2O)]24+, converting it to a higher-potential μ-dihydroxo form, μ-[FeIII(bpy)2(H2O)(OH)]24+, at lower pH. The existence of free bpyH22+ at low pH is found to strongly correlate with battery degradation. Near-neutral-pH RFBs employing a viologen anolyte, (SPr)2V, in excess with the [Fe(bpy)3]2+/3+ catholyte containing ACC exhibited high-voltage discharge for up to 600 cycles (41 days) with no discernible capacity fade. Correlating pH and voltage data offers powerful fundamental insight into organometallic (electro)chemistry with potential utility beyond battery applications. The findings, with implications toward a host of other "near-neutral" active species, illuminate the critical and underappreciated role of electrolyte pH on intracycle and long-term aqueous flow battery performance.

Improving adsorption materials properties for renewable energy-driven cooling systems

Considering addressing global warming and energy crises, this work presents an alternative cooling system based on adsorption technology. The novelty of this work lies in the improvement of the adsorption properties of the commercial adsorbent AquaSorb2000 (AS2000) for the first time by a chemical method. The AS2000 is improved by mixing with ammonium carbonate and thermally treated at 500 °C in a nitrogen gas flow. The raw AS2000 and the modified (MAS2000) adsorbents were characterized by X-ray powder diffraction, FTIR spectroscopy and N2 gas adsorption/desorption techniques. It was found that the modification led to significant surface changes. Adsorption isotherms of HFC-404A gas were investigated over AS2000 and MAS2000 adsorbents. Experimental results are fitted with Dubinin–Astakhov (D-A) and Sun-Chakraborty (S-C) equations for the isotherms and linear driving force and Fickian diffusion models for the kinetics. Moreover, the performance of the two materials is investigated for adsorption cooling systems (ADSs) using transient simulation modeling. The results showed improvement in the adsorption uptake from 0.50 kgR/kgAC of AS2000 to 0.99 kgR/kgAC of MAS2000 adsorbent. At the optimum conditions of the modified sample, the ADS performance parameters estimated by 124 W/kg specific cooling power (SCP) and 0.17 of coefficient of performance (COP) improved by 63 % and 70 %, respectively, compared to using the indicated original activated carbon material.

N,S‐Co‐Doped Activated Carbon Prepared by a Thiourea‐Assisted “Cutting” Method and their Application as High‐Performance Supercapacitors

AbstractBiomass has been considered a potential source for preparing carbon materials due to its environmentally friendly and renewable characteristics. In this work, N, S co‐doping activated carbon materials were easily prepared by using rice straw as the carbon source. In addition to being heteroatom source, thiourea can fragment the carbon particles into smaller pieces and create plenty of micropores during the carbonization process. Both theoretical and experimental analyses demonstrate that the incorporation of S and N species into carbon can improve the electrochemical performance of supercapacitors. The as‐made N, S co‐doping activated carbon materials, when used as electrodes, exhibit a high specific capacitance of 256 F g−1 at a current density of 1 A g−1 and maintain a good rate capacitance of 65 % even at a high current density of 50 A g−1. This work may offer valuable guidance for the application of rice straw derived carbon in supercapacitors.

Designing activated carbon and porous carbon nanofibers for insight into their differences in adsorption affinity mechanisms of VOCs

The adsorption technology has been considered as an effective and economical strategy to control volatile organic compounds (VOCs) through various types of porous materials. As two potential porous materials, activated carbon and carbon nanofibers were synthesized as VOCs adsorbents. In order to investigate the difference in the adsorption of VOCs between activated carbon and carbon nanofibers, the specific surface area, pore structure and chemical functional groups of VOCs adsorbent were analyzed. In particular, the carbon nanofibers (CNF) activated at 800 ℃ showed an excellent specific surface area (2524 m2·g−1), abundant pores (1.66 mL·g−1), and rich functional groups (N: 8.29 at%). Meanwhile, the carbon nanofibers had a better adsorption performance for acetone (1069.82 mg·g−1) and toluene (427.72 mg·g−1) than activated carbon materials. Furthermore, the theoretical calculations were conducted to reveal the mechanism of favorable adsorption on the CNFs. The theoretical adsorption energies of CNF are −31.9 kJ·mol−1 (acetone) and −67.5 kJ·mol−1 (toluene), respectively, which have more favorable adsorption sites and stronger charge redistribution than activated carbon. This research guided the approach to obtain the porous carbon nanofibers and provided the evidence for CNFs (curved carbon) exhibiting a better adsorption ability to VOCs.

A difunctional interlayer of an activated carbon cloth supported with MoO2 catalyst for high-rate magnesium–sulfur batteries

The main challenges faced by magnesium-sulfur (Mg–S) batteries are the polysulfide shuttle effect and slow kinetics of S cathode, causing the severe self-discharge behavior and rapid capacity decay. Herein, we elaborately design a MoO2-loaded activated carbon cloth (denoted as MoO2@ACC) functional interlayer to realize high-performance Mg–S batteries. The ACC possesses a remarkable adsorption effect, which can effectively mitigate the polysulfide shuttle effect and enable the Mg–S batteries with a high voltage plateau. Besides, the MoO2 can observably reduce the polarization during charge/discharge process attributed by the fast reaction kinetics due to the catalytic effect. The Mg–S battery with this MoO2@ACC interlayer achieves a high energy density and good capacity retention (80.3 %) after 100 cycles (0.5 C) and effectively mitigates the Mg–S battery's self-discharge as well. This work illustrates the significant role of the interlayer with both adsorption and catalytic functions to boost the usability of the Mg–S batteries.

Biomass-Derived Catalytically Active Carbon Materials for the Air Electrode of Zn-Air Batteries.

Given the growing environmental and energy problems, developing clean, renewable electrochemical energy storage devices is of great interest. Zn-air batteries (ZABs) have broad prospects in energy storage because of their high specific capacity and environmental friendliness. The unavailability of cheap air electrode materials and effective and stable oxygen electrocatalysts to catalyze air electrodes are main barriers to large-scale implementation of ZABs. Due to the abundant biomass resources, self-doped heteroatoms, and unique pore structure, biomass-derived catalytically active carbon materials (CACs) have great potential to prepare carbon-based catalysts and porous electrodes with excellent performance for ZABs. This paper reviews the research progress of biomass-derived CACs applied to ZABs air electrodes. Specifically, the principle of ZABs and the source and preparation method of biomass-derived CACs are introduced. To prepare efficient biomass-based oxygen electrocatalysts, heteroatom doping and metal modification were introduced to improve the efficiency and stability of carbon materials. Finally, the effects of electron transfer number and H2O2 yield in ORR on the performance of ZABs were evaluated. This review aims to deepen the understanding of the advantages and challenges of biomass-derived CACs in the air electrodes of ZABs, promote more comprehensive research on biomass resources, and accelerate the commercial application of ZABs.