Activated Carbon Samples Research Articles

Highly efficient peanut shell activated carbon via hydrothermal carbonization and chemical activation for energy storage applications

In this study, the activated carbon samples from peanut shells (PS) are synthesized through hydrothermal carbonization (HTC) with and without activating agents, and their electrochemical properties are studied for supercapacitor applications. The raw precursor (PS) powder is loaded with an activating agent (ZnCl2 or H3PO4 or KOH) during the hydrothermal treatment at 200 °C for 7 h. The treatment with the activating agent facilitates the generation of oxygen-containing functional groups on the precursor surface, enhancing the porosity and electrochemical performance of the sample. Further, the samples are subjected to carbonization at 400 °C for 3 h. The powder XRD patterns show peaks at around 24–26° and 43°, corresponding to the amorphous and graphitic carbon, respectively. The morphological examination reveals more meso and macro pores when treated with the activating agent. Raman spectra manifest the amorphous carbon nature of the samples exhibiting ID and IG bands. The porous carbon treated with H3PO4 shows a specific surface area of 17.8 m2/g and a pore volume of 0.037 cm3g−1. The H3PO4 treated sample shows a high specific capacity (Cs) of 240 F/g at 1 A/g current density, an energy density (E) of 4.08 W h kg−1, and a power density (P) of 101.3 W kg−1. The Retention rate of the sample is approximately 90 % up to 1200 cycles. These types of hybrid supercapacitor materials are suitable for battery-type applications.

Modelling and prediction of toluene adsorption saturation basing on characteristic values of activated carbons

Herein, the association between the dynamic adsorption capacity of toluene and several important characteristic values on activated carbon (AC) samples was investigated by multidimensional linear regression. Among the characteristic values, the carbon tetrachloride (CTC) adsorption value has demonstrated relatively stronger correlation with the toluene adsorption capacity on AC samples with diverse sources and forms, particularly in exposure to high-concentration toluene. Notably, the relevance of the toluene adsorption capacity to the CTC value could also be extended to a series of other porous adsorbents, which proved the wide applicability of CTC value in characterizing the adsorption behaviors. Based on these results, a mathematical and visual model was then established to predict the toluene adsorption saturation under different conditions (inlet concentration, adsorption time, initial CTC value, etc.) on diverse AC samples, of which the accuracy has later been verified by experimental data. As such, a fast and accurate estimation of the adsorption behaviors over AC samples, and possibly other porous adsorbents, was realized.

Production and characterization of activated carbon foams with various activation agents for electrochemical double layer capacitors (EDLCs) applications

Sucrose-based activated carbons were obtained by carbon foams with sugar and cobalt (II) nitrate as precursors, followed by using different chemical activation agents. The effect of Co(NO3)2 concentration, the carbonization temperature and the activation agent on the surface chemistry, porosity were investigated. Textural characterization and electrochemical tests were performed on the activated carbon samples (CF). The results showed that the activated carbon produced by H2SO4 and KOH at 800°C had a surface area of 691 m2/g and 1125 m2/g, 89% and 80% of the sample pore structure was microporous, and specific capacitance of 8.4 F/g and 162.2 F/g at a constant current density of 250 mA/g, respectively. K2CO3-activated carbon had 918 m2/g surface area and 63% of the sample pore structure with microporous and 1.4 F/g specific capacitance, H3PO4-activated carbon and ZnCl2-activated carbon had 1833 m2/g and 1597 m2/g surface area, 53% mesoporous and 50% mesoporous, 222.4 F/g and 149.9 F/g specific capacitance respectively. The most promosing result was observed in the electrochemical storage behavior of the carbon materials with hierarchical pore structure activated with H3PO4 is associated with increasing defect zones at the edges of micro- and mesoporous morphology, resulting in a higher surface area and increased conductivity of the material.

Sequestration of hexavalent chromium and paracetamol from water using deoiled hemp stem-twigs and roots and activated carbon

In the present study, deoiled hemp stem-twigs and roots and activated carbon were used to remove chromium and paracetamol. The hemp-based materials were characterized, and the surface area of the activated carbon samples increased more than 55-fold compared to the untreated materials. The pore volume of the carbon samples also increased, which can be attributed to the degradation of volatiles during carbonization and acid treatment. Contact time experiments showed that the uptake rate for hexavalent chromium was fast in the initial phase and equilibrium was reached in about 30 min for activated carbon from stem-twigs and activated carbon from hemp roots, while it took about 40 min for untreated hemp stem-twigs and untreated hemp roots. The trends for paracetamol show that the rate was slow compared to hexavalent chromium. Equilibrium was reached in about 120 min for all materials. pH solution 2 was optimal for the uptake of hexavalent chromium, while pH solution 6 was optimal for the adsorption of paracetamol. The data for enthalpy show that the sorption processes were endothermic and predominantly physisorptive. The values for Gibbs free energy were negative, indicating that the sorption was spontaneous and feasible.

Pore properties and CO2 adsorption performance of activated carbon prepared from various carbonaceous materials

In this study we prepared porous carbon samples from various carbonaceous materials, such as biomass and coal, and evaluated their CO2 adsorption performance. We first prepared activated carbon samples by heat treatment of the carbonaceous materials with a mixture of melamine as a nitrogen source and K2CO3 as a chemical activator. We then investigated their pore properties in detail and tested the CO2 adsorption performance of the prepared activated carbon samples. We found that activated carbon with well-developed pores could be prepared using materials with low carbon and ash content. Significant correlation was found among the specific surface area (SSA: 1840–2640 m2/g), micropore (0.85–1.46 cm3/g) volume, and CO2 adsorption of the prepared activated carbon samples, indicating that the SSA and micropore volume affected the CO2 adsorption performance (400–530 mg/g). Based on these results, we devised guidelines for producing activated carbon with high CO2 adsorption performance.

Bamboo and coconut shell based activated carbon: A Raman spectroscopic study

In this paper, we present a detailed report on Raman spectroscopic analysis of activated carbon (AC) samples obtained from two different biomass sources, namely, bamboo and coconut shell. The detailed analysis revealed that the local structure of the precursors was affected differently by the physical and chemical treatments prior to the preparation of AC. This leads to different structural features of the derived AC samples though processed under similar conditions. The influence of preparation methods and temperature on modifications in the D-, G-, and 2D-peak parameters of bamboo and coconut shell based AC (BAC and CSAC) such as peak positions, peak widths and peak intensity ratio were thoroughly described. We experimentally validate the stage-two of the three-stage Ferrari-Robertson phenomenological model of amorphous carbon for these biomass derived AC. We also show that the observed anomalies in the peak parameters are consistent with the stage-two process combined with the networking properties of biomass derived AC. Physically activated BAC and chemically activated CSAC prepared at a temperature of 600 °C showed greater disorder (ID/IG) values of 1.37 and 1.22 in their AC structures, respectively. Further analysis of 2D-peak indicated the greater turbostratic disorder (quasi 2D-continuous random network) in BAC compared to CSAC.

Sustainable removal of caffeine and acetaminophen from water using biomass waste-derived activated carbon: Synthesis, characterization, and modelling

The removal of caffeine (CFN) and acetaminophen (ACT) from water using low-cost activated carbons prepared from artichoke leaves (AAC) and pomegranate peels (PAC) was reported in this paper. These activated carbons were characterized using various analytical techniques. The results showed that AAC and PAC had surface areas of 1203 and 1095 m2 g−1, respectively. The prepared adsorbents were tested for the adsorption of these pharmaceuticals in single and binary solutions. These experiments were performed under different operating conditions to evaluate the adsorption properties of these adsorbents to remove CFN and ACT. AAC and PAC showed maximum adsorption capacities of 290.86 and 258.98 mg g−1 for CFN removal, 281.18 and 154.99 mg g−1 for the ACT removal over a wide pH range. The experimental equilibrium adsorption data fitted to the Langmuir model and the kinetic data were correlated with the pseudo-second order model. AAC showed the best adsorption capacities for the removal of these pharmaceuticals in single systems and, consequently, it was tested for the simultaneous removal of these pollutants in binary solutions. The simultaneous adsorption of these compounds on AAC was improved using the central composite design and response surface methodology. The results indicated an antagonistic effect of CFN on the ACT adsorption. AAC regeneration was also analyzed and discussed. A statistical physics model was applied to describe the adsorption orientation of the tested pollutants on both activated carbon samples. It was concluded that AAC is a promising adsorbent for the removal of emerging pollutants due to its low cost and reusability properties.

A Study on the Adsorption of Rhodamine B onto Adsorbents Prepared from Low-Carbon Fossils: Kinetic, Isotherm, and Thermodynamic Analyses.

The aim of this study was to obtain a series of activated carbon samples by the chemical activation of low-rank coal. The precursor was impregnated with a NaOH solution. Activated carbons were characterized by determining their textural parameters and content of surface oxygen functional groups and by using an elemental analysis. The carbons were tested as potential adsorbents for the removal of liquid pollutants represented by rhodamine B. The effectiveness of rhodamine B removal from water solutions depended on the initial concentration of the dye, the mass of rhodamine B, and the pH and temperature of the reaction. The isotherm examination followed the Langmuir isotherm model. The maximum adsorption capacity of the rhodamine B was 119 mg/g. The kinetic investigation favored the pseudo-second-order model, indicating a chemisorption mechanism. The thermodynamic assessment indicated spontaneous and endothermic adsorption, with decreased randomness at the solid-liquid interface. The experiment revealed that a 0.1 M HCl solution was the most effective regenerative agent.

Zn2+ modified activated carbon from spent mushroom substrate for organic wastewater treatment

In this work, a physical adsorption strategy including three steps of “turning waste into treasure-removal of pollutants-adsorption mechanism” have been provided to solve the environmental problems caused by spent mushroom substrate and organic pollution simultaneously. A series of environment-friendly Zn2+ modified activated carbon (AC) with adequate adsorption capacity are prepared by using spent mushroom substrate as raw material. X-Ray Diffraction results indicate weak graphitization of Zn2+ modified AC sample during the calcination process. FTIR results indicate that the AC adsorbents are inevitably entailed with abundant surface functional groups. Zn2+ modified AC calcinated at 600 °C (Zn-AC-600) has the bigger BET surface area of 450 m2·g−1 and excellent adsorption property, it can remove about 95, 75, and 88 % of Rhodamine B, Amoxicillin and Cefixime after 120 min adsorption process. While the maximal adsorption capacity qmax for Rhodamine B, Amoxicillin and Cefixime towards Zn-AC-600 sample is about 202, 123, and 130 mg·g−1, respectively. The adsorption process of all pollutants is found to match well with the pseudo-second-order kinetics. Zeta potential measurements reveal that Zn-AC-600 is negatively charged (-23.5 mV), which can absorb Rhodamine B, Amoxicillin, and Cefixime by electrostatic attraction. This work may provide an effective strategy toward beneficial recycling of spent mushroom substrate wastes and remove pollutants from water.

Synthesis of Activated Carbon from Rice Husk as A Filter For Iron (Fe) And Copper (Cu) In Well Water

This study focuses on the synthesis of activated carbon through the calcination method, designed as an absorber for iron (Fe) and copper (Cu) metals in well water previously investigated. The raw material utilized for activated carbon production is rice husk waste, with variations in calcination temperatures set at 700°C, 800°C, and 900°C. The characterization of the activated carbon involved XRD testing for phase analysis, SEM-EDX analysis on rice husk to discern the morphology and composition of the activated carbon components, and absorption performance analysis using AAS. The XRD testing results revealed an amorphous shape in samples calcinated at 700°C and 800°C. However, the 900°C samples exhibited the formation of the tridymite phase. SEM-EDX results showcased an increased surface area and a more compact pore structure, attributed to high-temperature calcination. AAS testing results indicated an improvement in the absorption capacity of iron (Fe) and copper (Cu) metals. In this research, each 4 g activated carbon sample proved most effective at reducing the initial iron (Fe) metal content from 8.06 mg/L to <0.009 mg/L, achieving an impressive 99.88% absorption. Furthermore, with every 2 g sample, copper (Cu) metal was efficiently absorbed, reducing the initial content from 3.99 mg/L to <0.006 mg/L, achieving a notable 99.85% absorption.

Heterostructure of Fe2O3 doped Alstonia Scholaris wood waste derived activated carbon based electrode for supercapacitor applications

The production of environmentally friendly and long-lasting supercapacitor electrodes employing activated carbons obtained from industrial wood waste from Alstonia Scholaris by traditional chemical activation using H2SO4 at High temperature activation is shown in this paper. The new traits of metal oxide (Fe2O3) doped Alstonia Scholaris wood derived activated carbon employing a slow precipitation technique. The produced activated carbon and the Fe2O3 doped activated carbon samples were examined using a variety of analytical methods, including XRD, FESEM, TEM-HRTEM, elemental mapping, N2 adsorption-desorption, Raman, XPS, and VSM. The BET result of prepared Fe2O3 doped activated carbon exhibits high surface area of 443 m2g−1. However, the assembled ASC cell exhibits high energy density of 38 Wh/kg and power density of 3181 W/kg. This work focuses on an innovative, straightforward process for producing low cost activated carbon from waste wood sources, which might have useful applications in the energy storage system.

Activated carbon treated with different chemical agents for pertechnetate adsorption

The study investigated the adsorption behaviour of different activated carbon samples for pertechnetate under diverse conditions. Characterizations of A-CF-F and A-CF-Z samples were done using BET, FTIR, XRD, XRF and SEM–EDX methods. In batch experiments, maximum adsorption occured at pH 2, with a swift process and an optimal phase mixing time determined as 1 h for all of the samples. Analyzing experimental data using Langmuir and Freundlich adsorption models revealed coefficients of determination R2 exceeding 90%. The Freundlich isotherm was found to be more suitable for describing the adsorption process.

Modeling of the evolution of the porous structure during a physical activation process for the production of activated biocarbon: A novel low conversion approach

Many experimental studies have shown the feasibility of using biomass precursors to produce activated carbon, often improving the properties obtained from traditional materials. However, hardly any models focus on the development of porosity during the process. Among the so-called pore models, the random pore model (RPM) is the most popular and accurately predicts the evolution of the porous structure due to pore growth and coalescence. However, in activation processes with a low degree of conversion, in which pore formation is the dominant mechanism, the RPM does not correctly predict the evolution of the specific surface area since it does not consider the appearance and creation of new porosity. In this work, a new model is proposed that predicts the specific surface area created due to the formation of new pores. Subsequently, it is combined with the determination of the variation of the specific surface area predicted by the RPM due to the growth and coalescence of existing pores. The validation of the new pore evolution model with activated carbon samples obtained at different conversions shows that the model proposed adequately predicts the specific surface area and pore distribution evolution throughout the activation process.

Synthesis and characterizations of conocarpus- and azadirachta-derived activated carbons as wastewater recycling material.

Water being the most important fluid supporting the life as well as industry is getting sparse and polluted day by day. Activated carbon (AC) can be utilized in various applications of significant environmental impact and sustainable living such as carbon dioxide sensing and capturing, air purification, and water recycling. However, in the wake of the recent corona pandemic which resulted in global lockdown and took the entire world by shock, a cost-effective and simple synthesis of such a useful material remains dire need of time. Therefore, this paper describes a simple and cost-effective synthesis of activated carbon (AC) of high porosity and surface area derived from the pruning of conocarpus and azadirachta trees. In reference to the study under consideration, alongside numerous others, a furnace was employed to synthesize activated carbon. However, our approach utilized a more conventional methodology wherein the environmental parameters were not optimized. In furnace-based procedures, factors such as temperature, pressure, and humidity are meticulously regulated, contrasting with the conventional methodologies where such parameters lack optimal control. Consequently, employing a furnace does not constitute a cost-effective approach for the physical activation of organic samples thus proving a furnace is not imperative for physical activation. The synthesis was carried out by physical activation in the form of carbonization followed by chemical activation with potassium hydroxide (KOH). The influence of activated carbon from each pruning over filtration of water containing industrial dye was investigated. Activation temperature and impregnation ratio of 600-800°C and 1:5 were selected respectively. X-ray diffraction patterns (XRD) for all AC samples indicted the appearance of broad peaks at 2θ value of 20-30° which confirms the presence of carbon in the sample. The physical morphology arrangement by SEM analysis showed uneven arrangement of pores of conocarpus which indicated higher iodine number and hence higher adsorption capacity of 442.13mg/g.

Electrochemical capacitance and hydrogen adsorption behavior of activated carbon derived from cattail fiber

AbstractIn this paper, we have reported the synthesis of activated carbon (AC) from biomass cattail fiber through hydrothermal carbonization, followed by chemical activation, and its electrochemical capacitance and hydrogen storage properties. The AC exhibits a Brunauer‐Emmett‐Teller (BET) surface area (SBET) of 1597.5 m2g−1, determined from the low‐pressure N2 adsorption isotherm at 77 K using a BET‐multipoint plot. The AC sample shows a reversible hydrogen adsorption capacity of 0.25 wt.% H2 (1.25 mmol H2 g−1) at 293 K and 74 atm. The capacitance performance of AC was investigated with various conductive additives such as carbon nanotubes (CNTs), carbon black (CB), and reduced graphene‐oxide (rGO). From galvanostatic charge discharge (GCD) and cyclic voltammetry (CV) measurements, the as‐derived AC with polymer binder exhibits a specific capacitance (Cs) of 245.2 F g−1 at 0.2 A g−1 and 158.1 F g−1 at 5 mV s−1. Among the investigated conductive additives, AC with CNTs in KOH electrolyte exhibit highest Cs of 326 F g−1 at 0.2 A g−1 and 173 F g−1 at 5 mV s−1. Furthermore, the symmetrical two‐electrode device fabricated using AC with CNTs (as a conductive additive) in 1 M aq. Na2SO4 electrolyte shows a Cs of 97.2 F g−1 at 0.1 A g−1. The energy and power densities of the two‐electrode device were observed to be 28 kW kg−1 and 2.64 Wh kg−1, respectively.

Preparation and characterization of cellulose-based activated carbon by cesium chloride chemical method

Carbon adsorbent material with a specific surface area as high as 436 m2/g was prepared by chemical activation method using cellulose as raw material and cesium chloride as activator, and its structure was characterized. Its adsorption performance on methylene blue solution was investigated, and the adsorption thermodynamics of crystalline violet dye at different temperatures was studied. The results showed that the surface of the prepared activated carbon material was smooth with abundant pores. The methylene blue adsorption value was as high as 176 mg/g, and it could adsorb methylene blue solution quickly and efficiently. It had good adsorption effect on crystal violet solution, the saturated adsorption amount reaches 281 mg/g at 40 °C, and the removal reached 92%, which indicated a self-heating adsorption reaction. Thus, CsCl could be used as an activator of wood raw material for the preparation of activated carbon samples.

Influence of SO2 on CO2 capture by adsorption on activated carbon: Individual pore performance via multiscale simulation

Carbon capture under post-combustion conditions has been the topic of numerous studies in the last decade. Although exhaust gases typically contain different components other than CO2, they are commonly neglected in these studies. The presence of sulfur dioxide, for example, tends to interfere in the carbon capture process through different mechanisms. The present work aimed to evaluate the effects of SO2 on the CO2 retention capacity through the integration of experimental evaluation, column dynamics modeling and molecular simulation (multiscale modeling) for an activated carbon sample under typical conditions found in the post-combustion environment. Results indicate that, under typical post-combustion flue gas conditions, SO2 has little influence on the CO2 retention capacity of the carbon in comparison to other adsorbent materials. The highest concentration of SO2 (5 000 ppmv) led to a decrease of approximately 10 % in the CO2 capture capacity. Significant deactivation (around 40 %) was observed experimentally and by molecular simulation only for very high concentrations of SO2 (50 000 ppmv). Additionally, no evidence of reactions with the material was found and both captured components could be completely desorbed by means of suitable regeneration methods. To access individual pore performance, molecular simulations were implemented for SO2 adsorption using, for the first time, a rigorous heterogeneous pore model (rMD). The results revealed a large deactivation for the 7.0 Å pore, a surprising cooperative effect for the 8.9 Å pore, and indifference for the larger 18.5 and 27.9 Å pores. For SO2 concentrations up to 5 000 ppmv, the use of carbon-based adsorbent could rule out the need of a pre-treatment operation to remove SO2 in carbon capture processes. For higher concentrations, molecular simulation showed that tailoring carbon porosity in the range of 7 Å to 8.9 Å considerably reduces the interference of SO2. Results also point out that the IAST and Langmuir models diverge from the molecular simulation results, particularly at low loadings (up to 5 000 ppmv SO2), indicating the need for caution when applying these models in systems where competitive interactions between molecules are relevant, as is the case with mixtures of CO2 and SO2.

Sustainable production of activated carbon from indigenous Acacia etbaica tree branches employing microwave induced and low temperature activation

Growing demand for activated carbon as an efficient and cost effective means of treating environmental pollution necessitates the economical production of good quality activated carbon. It is possible if it is done using low cost precursor materials and economical production methods. In the present study, two types of activated carbon were produced from Acacia etbaica tree branches while employing phosphoric acid as an activating agent. The first sample underwent carbonization by microwave irradiation (AC-MWI), while the second sample was carbonised in a furnace (AC-CA). Characterization of the formed activated carbon samples was executed by proximate and ultimate analysis adopting standard ASTM procedures. In addition to the elemental analysis, hardness, bulk density, pH, moisture and ash content, surface morphology, BET specific surface area, pore volume, volatile matter, fixed carbon, and iodine number were determined. Characteristics of both activated carbon samples were compared with the characteristics of activated carbon available in the literature and activated carbon available commercially in the market. The comparison revealed that the characteristics of the produced activated carbon samples was well comparable with the activated carbons produced from other species of Acacia tree and activated carbon available commercially. Results showed that the produced activated carbon demonstrated high activation efficiency of 39.8% and 48.7% for AC-CA and AC-MWI, respectively. Furthermore, AC-MWI has a BET specific surface area higher than that of AC-CA (1065 m2/g and 773 m2/g respectively). It was found that the BET specific surface area and pore volume of AC-MWI was higher by 37.7% and 12.7%, respectively, as compared to the values acquired for AC-CA. Additionally, activated carbon could be produced by microwave irradiation in about 48% less time as compared to traditional low temperature heating. The adsorption study of produced the activated carbon was performed utilising methylene blue (MB) as a contaminant, and the data was fitted to Langmuir, Freundlich, as well as Harkins–Jura isotherm showing comparable correlation. However, Freundlich isotherm was found to be the best to elaborate the MB adsorption on the produced activated carbon. The results confirmed the viability of microwave irradiation in producing good quality activated carbon from Acacia etbaica tree branches, which demonstrated comparable characteristics with commercially available activated carbon. The strategy could be beneficial for the country in order to produce high quality activated carbon and strengthen its self-reliance.

Green synthesis approach using deep eutectic solvents to enhance the surface functional groups on porous carbon for CO2 capture

This study explores the potential of green solvents using amino acids-based deep eutectic solvents to alter surface functionality of activated carbon thus enhancing the carbon dioxide (CO2) adsorption capacity. Green solvent is prepared by mixing an amino acid (L-Arginine) with ethylene glycol to form amino acid-based deep eutectic solvents. Amino acid-based deep eutectic solvents were used to modify the surface functionalities of activated carbon derived from palm shell waste. The change in surface functional groups and surface morphology of the modified activated carbon samples were characterized by Fourier-transform infrared spectroscopy and Scanning electron microscopy-energy dispersive X-ray analysis. Then, CO2 removal performance was performed using a packed-bed CO2 adsorption reactor to evaluate CO2 breakthrough time and adsorption capacity. CO2 adsorption experiments were measured at a certain temperature (25–45°C), at a fixed feed flow rate and CO2 concentration of 200 mL/min and 15%. It was observed that modified activated carbon showed the highest breakthrough time (15.2 min) compared to raw palm shell (5.2 min) at an adsorption temperature of 25°C. CO2 breakthrough times significantly decreased with increasing adsorption temperature because of physical adsorption.

Carbon composite of NiO hydrothermal impregnation from sugarcane bagasse and its electrochemical properties

Sugarcane bagasse (SB) can synthesize activated carbon (AC) through a two-step calcination process at calcination at 400oC and activation at 800oC. NaOH 0.1 M is used to activate the pre-carbonized sample in the activation step. The AC samples undergo hydrothermal impregnation with nickel oxide (NiO) at 110°C. The X-ray diffraction (XRD) pattern and Energy dispersive X-ray spectroscopy (EDX) confirmed the presence of NiO after this process. Scanning Electron Microscope (SEM) indicates the presence of pore structures in the sample morphology. A three-electrode system with 1 M Na2SO4 as an electrolyte was employed to assess the electrochemical properties. The specific capacitance for activated carbon derived from SB stands at 89.53 F/g at 0.05 A/g current density, while after impregnation with NiO, it increases to 250.53 F/g at the same current density. The results demonstrate the possibility of activated carbon from sugarcane bagasse waste composited with NiO as supercapacitor electrodes.