Properties Of Activated Carbon Research Articles

Air-mediated phosphoric acid activation strategy for preparation of oxygenated functional groups rich activated carbon for capacitive deionization

Atmosphere during H3PO4 activation is vital to the texture structure and surface-interface properties of activated carbon (AC), but the researches are way out of sufficiency. In this work, it is found that the air in the H3PO4 activation process is not only conducive to the introduction of more-oxidized oxygenated functional groups on ACs, but also beneficial to the formation of micropores rather than mesopores. Besides, as the air content increases in H3PO4 activation, the ACs’ ash, phosphorous content and conductivity reduce, but their wettability, disorder degree and defect number increase. In addition, the potential of zero charge of the as-prepared ACs is positively correlated with the O-CO content, which show a pattern of first increasing and then decreasing with the increase of air content. Benefit from the improved hydrophilicity, electrolyte-affinity, additional adsorption sites for sodium ions, the optimal AC exhibits excellent salt adsorption capacity of 12.08 mg g−1 and good cycling stability at 1.0 V in single-pass capacitive deionization. This work not only establishes a novel and effective method for regulating the texture structure and surface properties of ACs, but also provides promising cathode candidates for capacitive deionization application.

Activated carbon and their nanocomposites derived from vegetable and fruit residues for water treatment

Water pollution remains a pressing environmental issue, with diverse pollutants such as heavy metals, pharmaceuticals, dyes, and aromatic hydrocarbon compounds posing a significant threat to clean water access. Historically, biomass-derived activated carbons (ACs) have served as effective adsorbents for water treatment, owing to their inherent porosity and expansive surface area. Nanocomposites have emerged as a means to enhance the absorption properties of ACs, surpassing conventional AC performance. Biomass-based activated carbon nanocomposites (ACNCs) hold promise due to their high surface area and cost-effectiveness. This review explores recent advancements in biomass-based ACNCs, emphasizing their remarkable adsorption efficiencies and paving the way for future research in developing efficient and affordable ACNCs. Leveraging real-time communication for ACNC applications presents a viable approach to addressing cost concerns.

Biomass derived activated carbons in wastewater treatment – The aim of metallurgical industry

In the presented study, two commercial powder activated carbons (ACs) produced from low-cost biomass: coconut shells and wooden chips, were used in the adsorption process. The treated solution was wastewater obtained from production area of metallurgical industrial plant, which was analysed before and after the adsorption process using atomic absorption spectrometry (AAS). The adsorption process proceeded at two pH levels 7 and 9. The removed pollutants were Cd, Co, Cu, Ni, Sb, and Zn. Based on the adsorption results, the correlation between adsorption efficiency, pH and ACs properties was determined. The complicated composition of the tested wastewater causes that the adsorption mechanism did not have to be obvious due to the phenomena occurring in the multi-component system. Both ACs adsorbed ions efficiently, better results were obtained for AC derived from coconut shells. It was found that higher pH correlate with higher adsorption efficiency for every checked type of ions. AC with higher iodine number, mainly basic surface groups and higher micropores volume had better efficiency for adsorption Cd, Co, Cu, Ni and Zn. AC with higher surface area and presence of acidic surface groups only, had better efficiency in Sb adsorption process.

Machine learning application for predicting key properties of activated carbon produced from lignocellulosic biomass waste with chemical activation

The successful application of gradient boosting regression (GBR) in machine learning to forecast surface area, pore volume, and yield in biomass-derived activated carbon (AC) production underscores its potential for enhancing manufacturing processes. The GBR model, collecting 17 independent variables for two-step activation (2-SA) and 14 for one-step activation (1-SA), demonstrates effectiveness across three datasets—1-SA, 2-SA, and a combined dataset. Notably, in 1-SA, the GBR model yields R2 values of 0.76, 0.90, and 0.83 for TPV, yield, and SSA respectively, and records R2 of 0.90 and 0.91 for yield in 2-SA and combined datasets. The model highlights the significance of the soaking procedure alongside activation temperature in shaping AC properties with 1-SA or 2-SA, illustrating machine learning's potential in optimizing AC production processes.

Effect of Preparation Process on the Physicochemical Properties of Activated Carbon Prepared from Corn Stalks

The preparation of activated carbon (AC) from agricultural and forestry wastes is one of the effective methods for resource utilization. In this study, AC was prepared from corn stalk (CS) by pyrolysis, one-step activation, and two-step activation to determine the optimum preparation method. Based on this, a single-factor design was used to investigate the influence of activating agents (KOH, NaOH, KOH/NaOH), activation temperatures (600, 700, 800 °C), and activation times (60, 90, 120 min) on the physicochemical properties of AC. The physicochemical properties of AC were characterized by Thermal gravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Scanning electron microscopy (SEM), and Cyclic voltammetry (CV). The results showed that the AC obtained by the one-step activation method (KOH, 800 °C, 120 min) exhibited a rich pore structure and excellent electrochemical properties (Ipa = 159.8 μA, Ipc = −169.5 μA). However, for the two-step activation method, the AC exhibited a poor pore structure and electrochemical properties (Ipa = 130.8 μA, Ipc = −129.9 μA). In addition, one-step activation provides high-quality AC in a shorter activation time than two-step activation.

Integrated Constructed Wetland–Microbial Fuel Cell Systems Using Activated Carbon: Structure-Activity Relationship of Activated Carbon, Removal Performance of Organics and Nitrogen

This study designed integrated constructed wetland–microbial fuel cell (CW–MFC) systems using activated carbon (AC) as both CW substrates and MFC anodes and investigated the structure-activity relationship of six kinds of commercial columnar AC, as well as the organics and nitrogen removal, microbial activity and diversity of CW–MFCs. Results showed that the nitrogen adsorption by AC tended to be a linear process in which physical adsorption played a leading role and micropores made great contributions. A higher specific surface area, developed mesopores, and oxygen functionalities were conducive to the capacitance properties of AC, while a higher specific surface area and developed micropores were conducive to reduce material resistance and improve ion permeability. Coconut-shell-based AC had both excellent nitrogen adsorption capacity and electrochemical properties, making it ideal as both CW substrates and MFC anodes for CW–MFCs. The electricity generation, coulombic efficiency, internal resistance, and organics and nitrogen removal of CW–MFCs were positively correlated with the total depth of AC anodes. The total depth of AC anodes can be determined based on the influent organics/nitrogen loadings and organics/nitrogen removal load of AC, and a relatively smaller depth of a single AC anode (5 cm) was recommended. The MFC effectively improved the enzymatic activity (by 10.33% dehydrogenase, 8.72% catalase, and 7.35% ammonia monooxygenase), nitrification/denitrification intensity (by 9.53%/6.68%), and microbial diversity (by 1.64–4.07%) of AC (MFC anodes) in CW–MFCs, while the depth of a single AC anode barely influenced the microbial activity and diversity. MFCs increased COD and NH3-N removal in CW–MFCs by 11.60% and 3.4%, respectively. The increased total adsorption capacity of AC with the increase of its total depth narrowed the difference in COD removal resulting from the promotion of MFCs on organics degradation. MFCs increased TN removal in CW–MFCs by 5.29% through promoting denitrification in cathodes and enhancing NH3-N assimilation in anodes. The phyla of EAB (Proteobacteria, Bacteroidetes, Firmicutes, and Acidobacteria) and genera of EAB (Citrobacter, Geobacter, and Pseudomonas) accounted for 85–86% and 15.58–16.64% of the microbial community on AC anodes in CW–MFCs, respectively.

A Study on the Influence and Mechanism of Temperature and Dosage on PCDD/Fs Adsorption via Coal-Based Activated Carbon

Using a trace polychlorinated-ρ-dibenzodioxins and dibenzofurans (PCDD/Fs) stabilizing generator, an experimental study related to the influence of temperature (150, 165, and 180 °C) and activated carbon (AC) dosage (0.10, 0.15, and 0.20 g) on the adsorption effect of gas-phase PCDD/Fs via coal-based AC was conducted. Increasing the AC dosage is the most efficient method to improve the PCDD/Fs adsorption efficiency from 65.8% (0.10 g) to 93.0% (0.20 g) at 150 °C in an exponential trend. Both the polychlorinated-ρ-dibenzodioxins (PCDD)/polychlorinated dibenzofurans (PCDF) ratio and the Cl-PCDD/Fs value showed positive correlations, with the AC dosage under the same temperature. Increasing adsorption temperature declined the adsorption capacity of AC, resulting in the exponentially decreased average I-TEQ value adsorbed per gram of AC, from 131.3 ng TEQ/Nm3 (150 °C) to 55.9 ng TEQ/Nm3 (180 °C). The coal-based AC used in this study preferred to adsorb lower chlorinated PCDD/Fs, tetrachlorianted dibenzo-p-dioxin and dibenzofurans (TCDD/Fs), and pentachlorianted dibenzo-p-dioxin and dibenzofurans (PeCDD/Fs) than highly chlorinated PCDD/Fs, heptachlorianted dibenzo-p-dioxin and dibenzofurans (HpCDD/Fs), hexachlorinated dibenzo-p-dioxin and dibenzofurans (HxCDD/Fs), and octachlorianted dibenzo-p-dioxin and dibenzofurans (OCDD/Fs), which was aggravated by the increasing temperature. The characterization of the surface properties of AC revealed that slight oxidation occurred on the AC surface during the adsorption process, introducing oxygen to the competitive adsorption. In addition, it was found in this study that an increased temperature led to a higher content of hydrophilic carboxyl and anhydride groups and weakened π-π interactions, which were also partly responsible for the negative impact of the increasing temperature on the AC adsorption capacity. The results of this study can contribute to the operation optimization for controlling PCDD/F emissions from municipal solid waste incineration (MSWI).

Orange peel as a biosource for the synthesis of activated carbon and its application in hydrogen storage

AbstractBACKGROUNDThe reduction of fossil fuels and the environmental threats caused by their combustion has diverted the attention of the scientific community to search for renewable and environmentally safe energy sources. There are some advances in the development of activated carbons (ACs) from different wastes for use as adsorbents in hydrogen storage. In the present work, different ACs were synthesized using a domestic residue (orange peel) as a carbon source.RESULTSTo obtain these carbonaceous materials, a chemical activation was performed using phosphoric acid (50 wt%) as activating agent. Different synthesis conditions, acid/precursor ratio and contact time between them were used. The materials obtained through the revaluation of waste were applied to the adsorption of hydrogen as an alternative in the use of green hydrogen. Hydrogen adsorption was related to some textural properties of ACs, such as specific surface area and meso/microporosity. All the materials obtained have a high specific surface area (between 1000 and 1400 m2 g−1) and meso‐ and microporosity. X‐ray powder diffraction, scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, and Raman spectroscopy analyses were performed to characterize these materials.CONCLUSIONAdsorption increases practically linearly with respect to the specific surface area of ACs. Synergy can be observed between mesopores and micropores since increasing both microporosity and mesoporosity increases hydrogen storage. The highest adsorption capacity was 3.3 wt% at −196.15 °C and 10 bar. © 2023 Society of Chemical Industry (SCI).

Chemical and electrical properties of activated carbon from Samui Island young coconut waste

Solid coconut waste has been a chronic issue that can lead to an environmental problem in Samui Island. Therefore, we are interested in processing this waste into a more valuable product. Many previous studies have evaluated the characteristics of activated carbon (AC) using chemical properties, but not electrical properties. In this work, we analyze the electrical properties of AC to identify a wide range of potential applications. The whole coconut with husk was turned into AC under different activation parameters (temperature, impregnation ratio of KOH and time) using one-factor-at-a-time method. The results showed that with higher activation temperature (750-850°C), the iodine adsorption number increased but the yield decreased. Excessive impregnation ratio and longer activation time could lower the iodine adsorption number due to the collapse of micropores into larger pores. The SEM images revealed that after activation process, a well-developed pore structure is achieved. The highest iodine adsorption number was obtained at 1356.80 mg/g at activation condition of 800°C, impregnation ratio of 1:2 and activation time of 2 hrs. The electrical property of activated carbon was remarkably improved from the initial char, in accordance with the iodine number result. The lowest resistivity was also achieved at the same condition as above.

A Review of Bio-Based Activated Carbon Properties Produced from Different Activating Chemicals during Chemicals Activation Process on Biomass and Its Potential for Malaysia

Activated carbon is the preferred adsorbent for gas and water treatment in various industry across the world due to its efficiency, reliability, and accessibility. Recently, in Malaysia, studies are mainly focused on the fabrication of activated carbon from lignocellulosic biomass-based precursors from agricultural waste such as coconut shell, rice husk, and palm kernel shell. Activated carbon fabrication is a two-step process; the precursor will first undergo carbonization, then, activation is carried out either physically or chemically to develop its porous surface for adsorption purposes. The main benefit of activated carbon is the customizable pore structure for different utilization, which can be easily achieved by the chemical activation process. The types and concentration of chemicals used for activation, pre-treatment of precursor, duration of the activation process, and the mass ratio of precursor to chemicals are proven to effectively influence the resulting pore structure. However, the chemicals used in the activation process can be harmful to the environment. Thus, the chemical recovery process is necessary after the activation process. Nonetheless, more in-depth research on producing activated carbon from abundant biomass materials with bio-based chemical agents for activation is needed to achieve an ecological and sustainable manufacturing process.

New insights into the chemical activation of lignins and tannins using K2CO3—a combined thermoanalytical and structural study

Engineering of activated carbons (ACs) through chemical activation of organic precursors has been extensively studied for a wide variety of biopolymers, biomasses, wastes and other fossil-based precursors. Despite huge efforts to engineer evermore performant and sustainable ACs, “searching-for-the-best-recipe” type of studies are more the rule than the exception in the published literature. Emerging AC applications related to energy and gas storage require strict control of the AC properties and a better understanding of the fundamentals underlying their engineering. In this study, we provide new insights into the K2CO3 chemical activation of plant-based polyphenols—lignins and tannins—through careful thermoanalytical and structural analyses. We showed for the the first time that the reactivity of polyphenols during K2CO3 chemical activation depends remarkably on their purity and structural properties, such as their content of inorganics, OH functionalities and average molecular weight. We also found that the burn-off level is proportional to the K2CO3/lignin impregnation ratio (IR), but only within a certain range—high impregnation ratios are not needed, unlike often reported in the literature. Furthermore, we showed for the first time that the K2CO3 chemical activation of different carbon surfaces from lignins and tannins can be modelled using simple global solid-state decomposition kinetics. The identified activation energies lay in the range of values reported for heterogenous gas-carbon surface gasification reactions (O2-C, H2O-C, or CO2-C) in which the decomposition of C(O) surface complexes is the common rate-limiting step.

Mesoporous carbon supported Cu as the efficient catalyst for flow hydrogenation processes toward formation of products with pharmaceutical potential

Herein, we investigate the influence of active carbon properties, metal loading and metal dispersion on the catalytic performance of Cu/C catalysts in liquid phase flow selective hydrogenation of 2-methyl-3-butyn-2-ol, 2-butyne-1,4-diol, and 2-methyl-2-pentenal towards the formation of products with pharmaceutical potential. We have shown the beneficial role of carbon Norit CNR115 on the catalytic performance of Cu/C materials in hydrogenation processes. Our studies also allowed the determination of the optimal reaction parameters and the best Cu dispersion for three hydrogenations. 93% of 2-methyl-3-buten-2-ol (vitamin A and E precursor) was formed at 97% conversion of 2-methyl-3-butyn-2-ol at mild conditions (1 bar, 45 °C) on 2 wt% Cu. 90% of the selectivity towards 2-butene-1,4-diol (precursor of vitamin B6, antibiotics, antitumoral and antiepileptic drugs) at 66% of conversion was obtained at 1 bar and 10 °C during 2-butyne-1,4-diole hydrogenation on 2 wt% Cu. Chemoselective hydrogenation of 2-methyl-2-pentenal with 81% of conversion leads to the formation of 100% of 2-methylpentanal at 45 °C and 60 bar for 6 wt% Cu.

Preparation and Characterization of Activated Carbon/Polymer Composites: A Review.

Activated carbon (AC) and activated carbon fibers (ACFs) are materials with a large specific surface area and excellent physical adsorption properties due to their rich porous structure, and they are used as electrode materials to improve the performance of adsorbents or capacitors. Recently, multiple studies have confirmed the applicability of AC/polymer compo-sites in various fields by exploiting the unique physical and chemical properties of AC. As the excellent mechanical properties, stability, antistatic and electromagnetic interference (EMI) shielding functions of activated carbon/polymer composite materials were confirmed in recent studies, it is expected that activated carbon can be utilized as an ideal reinforcing material for low-cost polymer composite materials. Therefore, in this review, we would like to describe the fabrication, characterization and applicability of AC/polymer composites.

Biomass-derived activated carbon nanocomposites for cleaner production: A review on aspects of photocatalytic pollutant degradation

Nowadays, water contamination resulting from the disposal of industrial and urban waste poses a significant threat to marine life and human. Hence, providing an effective treatment approach to reduce the total cost and duration of the wastewater treatment process is crucial. Although the adsorption and photocatalysis methods show superb potential for removing hazardous pollutants from water, their combination through a suitable synthesis route is one of the most effective ways to overcome their limitations. Activated carbon (AC) significantly accelerates the rate of pollutant degradation for AC-based photocatalysts compared to bare photocatalysts because of its ability to increase the number of attachment sites, strengthen the interaction between pollutants and photocatalysts, and facilitate rapid electron transfer to prevent electron or hole recombination. This study aims to investigate four main objectives: 1) evaluating key parameters to enhance the surface characterization of AC-derived from lignocellulosic sources using physical and chemical techniques; 2) Surveying various approaches for synthesizing AC-based photocatalysts; 3) explaining the mechanism of photocatalytic degradation of pollutants and the operating parameters in the wastewater treatment process; and 4) providing an overview of the opportunities, challenges, suggestions, and potential future outlooks. Future studies should focus on understanding the structural properties of AC to design effective photocatalytic systems for degrading hazardous contaminants. Generally, AC-based nanocomposites reduce both process costs and duration and promote environmental sustainability by effectively eliminating pollutants.

Activated carbon derived from radiation-processed durian shell for energy storage application

A lignocellulosic biomass, durian shell, modified by radiolytic oxidizing species from gamma and electron beam irradiations, has been used as a starting material for activated carbon (AC) production. Facile hydrothermal carbonization with ZnCl2/FeCl3 and physical activation were employed in addition. The physicochemical and energy storage properties of the graphitic carbons were investigated using Field Emission Scanning Electron Microscope (FESEM), N2 adsorption-desorption, Brunauer-Emmett-Teller (BET), Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Raman spectroscopy, Cyclic Voltammetry (CV), Galvanostatic Charge-Discharge (GCD) and Electrochemical Impedance Spectroscopy (EIS). Biomass modification by radiolytic oxidizing species aided in improving the energy storage properties of the resultant ACs without significantly changing the textural qualities. The radiation type played an important role on the surface functional groups, basal plane, and pore structures of the graphitic materials. The energy storage mechanism was based on a combination of EDLC and pseudo capacitances with high Coulombic efficiency. The highest specific capacitance obtained was 325.20 F/g providing capacity retention of 94.79 % after 10,000 cycles. A promising method of AC production for energy storage application has therefore been successfully demonstrated.

High Adsorption Capacity of Ammonia Gas Pollutant Using Adsorbents of Carbon Composites

Air pollution is one of the most environmentally harmful to the human health and the climate change. The present study is aimed to investigate the effectiveness and capability of novel composite adsorbents prepared from modification of activated carbons (ACs) in the removal of air pollutants. The effect of both triethoxysilane propylamine (TEPSA) and carbon nanotube (CNT) on the adsorption properties of AC (TEPSA/CNT/AC); in addition, silica gel prepared from TEPSA to form silica nanoparticles (SiNP) along with CNT and AC (SiNP/CNT/AC), was studied. Ammonia gas (NH3) was used in this study as a typical emerging gas air pollutant. The physicochemical characteristics of the prepared ACs samples were analyzed using BET surface area, SEM, EDX, TEM and FTIR. Their results proved considerable changes in the porosity and surface functional groups after modifying AC surface with TEPSA or SiNP and CNT instantly. The adsorption findings showed that the NH3 removal efficiency using the prepared AC samples reached almost 97, 86 and 75% during 90 min at 25 °C for each sample of SiNP/CNT/AC, TESPA/CNT/AC and AC, respectively. Adsorption of NH3 relied mainly on the presence of silica particles and mesopore distributions in CNT rather than large total surface area in AC alone. Thus, the combination of SiNP as silanol and siloxane groups with CNT on AC surface raised significantly the adsorption capacity of NH3 from 194 to 300 mg/g. Conclusively, the SiNP/CNT/AC sample exhibited the best performance among all prepared samples used for the adsorption of NH3 gas from the indoor air. Also, Langmuir and Freundlich models were applied, and the results revealed that Freundlich model fits well the equilibrium adsorption data.

Thermal treatment of H3PO4-impregnated hydrochar under controlled oxygen flows for producing materials with tunable properties and enhanced diclofenac adsorption

The chemical activation of biomass with phosphoric acid under an oxygenated atmosphere has been extensively studied in various papers. However, there is still uncertainty about how the oxygenated atmosphere affects the evolution of activated carbon properties, as the concentration of oxygen in the activation atmosphere has not been explored as an activation variable. Hence, this paper aims to fill the gap by exploring the effect of oxygen concentration on the activation process. The H3PO4-impregnated hydrochar was heated at 500 °C, under atmospheres containing various concentrations of oxygen. The evolution of activated carbons' properties was assessed by various techniques, including FTIR, SEM-EDS, N2-physisorption, CHNS/O elemental analysis, pHpzc, and Boehm titration. Additionally, the impact of oxygen concentration on the adsorption capacity was examined using diclofenac as a model pollutant. It was found that the activated carbons’ microporosity and surface functionality can be improved and controlled by changing the oxygen concentration in the activation atmosphere. This led to enhanced π-π and hydrogen bonding interactions between diclofenac molecules and activated carbons, resulting in increased adsorption capacities. This study emphasizes the importance of oxygen concentration as an activation variable, providing valuable insights for designing effective activated carbon adsorbents.

Demineralization of common ivy-derived biomass and biochar and its effect on the resulting activated carbon properties

Biomass waste often contains high amounts of inorganic impurities, which is a limitation for developing high-quality bioproducts, e.g., high-purity activated carbons (ACs). Otherwise, these would be applicable to purify polluted water and air streams. Conventionally, AC’s are purified with non-sustainable and corrosive inorganic acids. This study illustrates the successful removal of the impurities from common ivy, Hedera helix L., through treatment with a natural deep eutectic solvent (NADES), namely choline chloride-malic acid (CCl:MA, 1:1 M). The demineralization efficiency is benchmarked against H2O and dilute hydrochloric acid (HCl). Moreover, the importance of the process sequence, pre- or post- pyrolysis demineralization, for AC-production was investigated. The three solvents showed different biomass (pre-pyrolysis) demineralization efficiencies, they were ranked, from best to worst, as follows: HCl > CCl:MA > H2O. However, demineralizing the biomass after pyrolysis yielded highly porous ACs, with a good mix of meso-and micropores. In this case, no differences in removal performance could be observed between HCl and CCl:MA. Lastly, the ACs phosphate adsorption capacity was highest after demineralizing biomass with either H2O or CCl:MA. Ultimately, this investigation demonstrated CCl:MA’s potential as a green demineralization agent to treat metal-contaminated biomass in future bio-refinery processes.

Prediction of structural properties of activated carbons derived from lignocellulosic biomass components using mixture design of experiments

There is significant interest in using biomass to produce activated carbons for applications such as environmental remediation, energy storage, and construction. To date, the research has primarily focused on exploring the potential of individual biomass sources. There is little research on how interactions between the fundamental components of lignocellulosic biomass affect activated carbons' structural properties, and, therefore, their suitability for various applications. This investigation sought to address this knowledge gap by exploring how the relative compositions of cellulose nanofibers, cellulose nanocrystals, and lignin affected the final properties of activated carbons produced through a two-step KOH activation process. A simplex-lattice mixture design was used to understand how the composition affected activated carbon yield, specific surface area, and micropore fraction. Mixture regression models showed that the specific surface area was highest when the activated carbon was composed of 16.7% cellulose nanofibers, 16.7% cellulose nanocrystals, and 66.7% lignin by mass. In addition, the micropore fraction was largest at 76.3% while also maintaining a high surface area, with a precursor mixture of 50% cellulose nanocrystals and 50% lignin by mass. The results of this investigation provide a foundation for future efforts to be able to predict, and tune, activated carbon properties based on biomass composition.

Structural changes and electrochemical properties of mesoporous activated carbon derived from Eucommia ulmoides wood tar by KOH activation for supercapacitor applications

In this study, mesoporous activated carbon (AC) was synthesized by thermochemical activation of Eucommia ulmoides Oliver (EUO) wood tar by using KOH as the activator. The pore structure, surface characteristics, graphitization degree and electrochemical properties of ACs synthesized by one-step and two-step activation were systematically investigated. The results showed that the two-step activation could effectively improve the relevant properties of AC as compared to those from the one-step activation. The maximum specific surface area (SSA) and pore volume of AR3–1 (1:3 mass ratio of EUO wood tar to activator at one-step activation process) could be increased than AR3–2 (1:3 mass ratio of carbonized product to activator at two-step activation process) by 26.08% and 20.27%, respectively. Additionally, the mesoporous ratio of AR3–2 can reach 71%, indicating a well-developed mesoporous structure. Meanwhile, the highest SSA of AR5–2 (1:5 mass ratio of carbonized product to activator at two-step activation process) synthesized by two-step activation can rise to 3354.8 m2/g, and the pore volume can reach 1.78 m3/g. Besides, the specific capacitance of AR3–2 reached 510.54 F/g at a current density of 0.2 A/g in 1 M KOH aqueous electrolyte in the three-electrode system, possessing better electrochemical stability. Overall, as a precursor of mesoporous activated carbon, the AC synthesized from EUO wood tar exhibits excellent structural and electrochemical performance. This study has a guiding significance for the synthesis of high-performance mesoporous carbon from biomass tar.