Activated Carbon Materials Research Articles

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.

Preparation and characterization of polyvinyl chloride based carbon materials with high specific surface area

Using PVC as raw material and KOH as activator, the carbon adsorption material with ultra-high specific surface area up to 5677.2 m2/g was prepared by chemical activation method, and its structure was characterized to study its adsorption performance on methylene blue solution; the activated mixture was analyzed for chlorine element and the recovery of chlorine element was calculated. The results show that the surface of the obtained activated carbon material is in the shape of smooth lotus root flakes with well-developed pore structure; the adsorption value of methylene blue adsorption can reach 765.0 mg/g, which can adsorb methylene blue solution quickly and efficiently; the elemental chlorine can be recovered efficiently with a recovery rate of 95.33 %, which can effectively reduce the toxic hydrogen chloride gas produced in the process of PVC pyrolysis. Excellent adsorption capacity of H2, CO2 and CH4. This experiment can provide an effective method for the harmless treatment of PVC.

Orange peel magnetic activated carbon for removal of acid orange 7 dye from water

Magnetic activated carbon resources with a remarkably high specific surface area have been successfully synthesized using orange peels as the precursor and ZnCl2 as the activating agent. The impregnation ratio was set at 0.5, while the pyrolysis temperature spanned from 700 to 900 °C. This comprehensive study delved into the influence of activation temperatures on the resultant pore morphology and specific surface area. Optimal conditions were discerned, leading to a magnetic activated carbon material exhibiting an impressive specific surface area at 700 °C. The Brunauer–Emmett–Teller surface area reached 155.09 m2/g, accompanied by a total pore volume of 0.1768 cm3/g, and a mean pore diameter of 4.5604 nm. The material displayed noteworthy properties, with saturation magnetization (Ms) reaching 17.28 emu/g, remanence (Mr) at 0.29 emu/g, and coercivity (Hc) of 13.71 G. Additionally, the composite demonstrated super-paramagnetic behaviour at room temperature, facilitating its rapid collection within 5 s through an external magnetic field. Factors such as absorbent dose, initial concentration of the adsorbate, contact time, and pH were systematically examined. The adsorption behaviour for acid orange 7 (AO7) was found to adhere to the Temkin isotherm models (R2 = 0.997). The Langmuir isotherm model suggested a monolayer adsorption, and the calculated maximum monolayer capacity (Qm) was 357.14 mg/g, derived from the linear solvation of the Langmuir model using 0.75 g/L as an adsorbent dose and 150–500 mg/L as AO7 dye concentrations. The pseudo-second order model proved to be the best fit for the experimental data of AO7 dye adsorption, with a high coefficient of determination (R2) ranging from 0.999 to 1.000, outperforming other kinetic models.

A novel activated carbon material from peanut shells for the removal of methyl orange and methylene blue dyes from wastewater: kinetics, isotherms and mechanism

A novel activated carbon material from peanut shells for the removal of methyl orange and methylene blue dyes from wastewater: kinetics, isotherms and mechanism

EFFICIENT AND REUSABLE MATERIALS WITH PYROCHLORE STRUCTURE FOR REMOVING RED DYE FROM AQUEOUS MEDIA

Mixed oxides of pyrochlore structure of the type La2Zr2O7 and La2M0.3Zr1.7O7 (M = Fe or Ni) were synthesized through the modified proteic method and calcined at 900 °C for 2 h, this is a synthesis route not yet explored for materials with this structure and were characterized by X-ray diffraction, scanning electron microscopy images, point of zero charge (PZC) and specific surface area. Its abilities to remove pollutants from aqueous media by adsorption process were investigated using a model compound. Data analysis revealed that the synthesized materials correspond to the pyrochlore phase (La2Zr2O7). They present particulate morphology with grains of different sizes and pores in their structure. The results of the adsorption studies show that the materials are efficient adsorbents for the removal of model compound in aqueous media, with efficiency above 90%. The adsorption kinetics of the compound in the adsorbents was studied. The materials were applied in reuse studies five times and maintained high efficiencies, highlighting the better performance presented by the material without doping. The obtained adsorbents were also submitted to removal of contaminants of industrial effluent tests and compared with the silica gel and activated carbon materials and also proved to be promising materials.

Unravelling the role of pore structure of biomass-derived porous carbon in charge storage mechanisms for supercapacitors.

This study presents findings on the production and analysis of activated carbon (AC), which exhibits a significantly expansive surface area derived from readily available and inexpensive agroforestry waste, specifically coconut shells. The carbon materials displayed encouraging features for electrochemical energy storage applications with a high specific surface area (2920 m2 g-1), an ordered mesoporous structure (∼2.5 nm), and substantial electronic conductivity. By altering the surface properties of AC materials, they exhibited different energy storage responses while using an ionic liquid as an electrolyte. Electrodes composed of AC sourced from coconut shells demonstrated notably high specific capacitance (78 F g-1) and retained capacitance when assessed within symmetric electrical double-layer capacitors (EDLCs) employing organic electrolytes. Interestingly, the AC cell in an organic electrolyte delivered a specific energy (Es) of 67 W h kg-1 at a specific power (Ps) of 1237 W kg-1 at the current density of 1 A g-1 and still provided Es of 64, 60, 58, 57, and 52 W h kg-1 at Ps of 2477, 3724, 4971, 6218 and 12 480 W kg-1 at the current density of 2, 3, 4, 5 and 10 A g-1. This work demonstrates the effect of different pore volumes on the electrocatalytic activity of AC derived from natural product waste. Our results indicate the feasibility of employing these electrodes for lab-scale applications. Thus, the AC material emerges as a highly promising substance, poised to advance the creation of cost-efficient, environmentally sustainable, high-performance, high-power devices.

Targeted design strategies for a highly activated carbon cloth cathode/anode to construct flexible and cuttable sodium Ion capacitors with an all-woven-structure

A flexible carbon cloth cathode and anode with high energy storage activity are constructed via targeted strategies using cotton cloth. The assembled all-cloth sodium ion capacitor provides stable power output even under bending/cutting conditions.

Axial ligand-induced high electrocatalytic hydrogen evolution activity of molecular cobaloximes in homo- and heterogeneous medium.

Three new molecular cobaloxime complexes with the general formula [ClCo(dpgH)2L] (1-3), where L1 = N-(4-pyridylmethyl)-1,8-naphthalimide, L2 = 4-bromo-N-(4-pyridylmethyl)-1,8-naphthalimide, L3 = 4-piperidin-N-(4-pyridylmethyl)-1,8-naphthalimide, have been synthesized and characterized by UV-Vis, multinuclear NMR, FT-IR and PXRD spectroscopic techniques. The crystal structures of all complexes have also been reported. The electrocatalytic activity of complexes is investigated under two catalysis conditions: (i) homogeneous conditions in acetonitrile using acetic acid (AcOH) as a proton source and (ii) heterogeneous conditions upon immobilization onto the surface of activated carbon cloth (CC). Complex 3 exhibited high electrocatalytic HER activity under both homogeneous and heterogeneous conditions. It catalyses proton reduction to molecular hydrogen in acetonitrile solution at a lower overpotential (640 mV) with a high turnover frequency (TOF) of 524.57 s-1 and demonstrates good stability in acidic conditions. Furthermore, catalytic (working) electrodes are prepared by immobilizing the complexes onto the surface of activated carbon cloth (CC) for electrocatalytic HER under heterogeneous conditions. An impressive HER performance was again obtained with catalytic electrode 3@CC in 1.0 M KOH, achieving a current density of -10 mA cm-2 at an overpotential of 262 mV. Chronoamperometric (CA) studies showed no significant decay of the initial current density for 10 h, indicating the excellent stability of 3@CC. Additionally, UV-Vis and NMR spectral studies of the recovered catalyst after electrocatalysis revealed no structural changes, demonstrating its robustness under reaction conditions.

Preparation of Activated Carbon Materials from Coal Gasification Ash and Removal of Complexed Copper

Preparation of Activated Carbon Materials from Coal Gasification Ash and Removal of Complexed Copper

The beneficiation of asphalt waste through conversion into an efficient activated carbon adsorbent for diazinon pesticide, optimized through response surface methodology

This study reports on converting waste into an activated carbon material for the efficient removal of diazinon pesticide (DP).

Bio Adsorbent Lemon Peels Charcoal to Remove Fe (III) from Water Sources

This study describes the creation of a low-cost activated carbon from lemon peels material extract as a precursor which is made from inexpensive lemon peels through a simple calcination process at 500°C and a green extraction with water. Nitrogen adsorption-desorption, FTIR analyses, and transmission electron microscopy were used to characterize the samples. The surface area of the obtained mesoporous lemon peels-derived activated carbon material was 282 m2/g1, and the pore size was 5.7 nm. For the adsorption of Fe (III) ions, an excellent adsorbent was obtained. Maximum Fe (III) ion adsorption capacity was 117.9 mg/g, and the effect of temperature, and time on its adsorption capacity were also investigated. The kinetic data fit the pseudo-second-order mode well, and the adsorption isotherms were confirmed with the Langmuir model. The thermodynamic results Negative values of G° indicate that the adsorption process was spontaneous, and negative values of entropy S° indicate that the state of the adsorbate at the solid/solution interface became less random during the adsorption process. According to the findings, prepared lemon peels-derived activated carbon has a high potential for removing heavy contaminating metal ions Fe(III) from aqueous solutions as a low-cost alternative to commercial adsorbents

Shape-transformable long-lasting superhydrophilic carbon cloth for sustainable solar vapor generation

Global water scarcity has spurred the quest for eco-friendly, cost-effective solar-based water desalination and purification methods. However, creating an efficient and durable solar evaporator still remains a formidable challenge. Here, we demonstrated that a rapid and straightforward air plasma activation process can transform a commercially available hydrophobic carbon cloth into a shape-transformable superhydrophilic solar evaporator enriched with nitrogen and oxygen dopants. The activated carbon cloth preserved the merits of the original material and exhibited long-term wettability and salt-rejection properties which are critical for the realization of stable solar vapor generation. Notably, the resulting activated carbon cloth achieved a remarkable vapor evaporation rate of 1.78 kg m-2 h-1 under one-sun irradiation, likely thanks to the abundance of surface intermediate waters that reduce the enthalpy required for evaporation. Furthermore, the constructed column-like solar evaporator with a 5-cm height exhibited an impressive evaporation rate of 3.82 kg m-2 h-1 under one-sun irradiation.

Natural polymers as sustainable precursors for scalable production of N/SOx doped carbon material enabling high‐performance supercapacitors

AbstractNatural polymers‐based carbon electrodes have gained significant research attention for next‐generation portable supercapacitors. Herein, present an environmentally benign and novel approach for the synthesis of N/S‐Ox carbon material derived from natural polymers on gram scale. By capitalizing the synergistic effect of sulfonated lignin and amino‐containing chitosan, this methodology produces a straightforward, low‐budget, and scalable process. The incorporation of sulfonate motifs from lignin contributes to the formation of C‐SOx moieties and multi‐porous architecture with a high surface area. Simultaneously, amino groups in chitosan induce nitrogen doping, enhancing conductivity, and wettability. The resulting N/SOx carbon material exhibits a micro/meso‐porous architecture, facilitating electrolyte diffusion, and demonstrating improved rate capability and pseudocapacitance via Faradaic redox reactions. The N/SOx carbon material showcases notable capacitance (392 F g−1 at 1 Ag−1) as compared with the reported carbon materials form biomass and outstanding cyclic stability (94.8% retention after 5000 cycles). By optimizing various chitosan mass ratios, the most effective N/SOx carbon material SNACM = S/N‐doped activated carbon material (SNACM‐2) was produced using a lignin: chitosan sample ratio of 1:2 for symmetric supercapacitors. Furthermore, the quasi‐solid‐state symmetric supercapacitors based on SNACM‐2 exhibit an excellent specific capacitance of 142 F g−1 at 1 A g−1, coupled with outstanding flexibility. The SNACM‐2 demonstrates a high‐energy density of 9.8 W h kg−1 at a power density of 0.5 kW kg−1. This study presents a successful strategy for transforming low‐valued, eco‐friendly natural polymers into renewable, high‐performance carbon materials for supercapacitors.image

Investigating the impact of pore structure and surface chemistry on CO2 adsorption in graphitic slit-pores using GCMC simulation

Carbon capture, storage, and utilization from post-combustion processes using adsorption phenomena has emerged as a promising solution to the greenhouse gas emission crisis. The capacity of solid porous adsorbents dictates the performance of such carbon capture processes. Developments of porous adsorbents with favourable structural and chemical characteristics of the pore have been a major research area. Computational tools, notably the Grand Canonical Monte Carlo (GCMC) simulation, are widely employed to characterize the adsorption process in crystalline adsorbents like metal-organic frameworks and zeolites. Activated carbons are becoming promising alternatives to conventionally-used zeolite adsorbents for CO2 adsorption, because of their abundant microporosity and cost performance. However, the amorphous nature of the activated carbon materials poses a challenge in accurately modelling their pore characteristics and their adsorption process. Therefore, this study systematically explores the effect of pore size distribution and type of functional groups on the adsorption of CO2 on activated carbons using a simplified slit-pore graphite structure representing the activated carbon adsorbent. Four different pore sizes (7 Å, 8.9 Å, 18.5 Å, and 27.9 Å) and three oxygen-containing functional groups (Carbonyl, Hydroxyl, and Carboxyl) were selected to model the graphite structures. Results from the GCMC simulation reveal a significant rise in the CO2 adsorption capacity (from 4 mmol/g to 21 mmol/g) as the pore size was increased from 7 Å to 27.9 Å. Likewise, the functional groups enhance the low-pressure adsorption process by reducing the onset pressure of the pore filling by a factor of 100, especially in ultra-micropores. Likewise, we demonstrate the increase in the isosteric heat of adsorption due to the reduction in the pore size and the presence of functional groups. Additionally, the study illustrates the adsorbed phase behaviour of CO2 concerning the pore characteristics, a facet often overlooked in the existing literature. The adsorbed phase local density and molecular orientation distribution are analysed to understand the variation in the adsorption uptake and isosteric heat of adsorption properties. The study further identifies the adsorbed phase monolayer to multilayer transition and the ‘T′-shaped orientation of the adsorbed CO2 molecules as the key contributors to the high isosteric heat of adsorption in 8.9 Å pore size. It is envisaged that this study will navigate the precision adsorbent development for an efficient carbon capture process.

Nanomaterial grafted polymorphous activated carbon cloth surface for antibacterial, capacitive deionization and oil spill cleaning applications

This work reports the development of multifunctional or polymorphous surfaces using zinc oxide (ZnO) nanorods, silica (SiO2), and fluoropolymer functionalization in a sequential process. Firstly, zinc oxide nanorods were grown on activated carbon cloth (ACC) using a simple low-temperature synthesis process. ZnO nanorods-coated ACC substrate was applied to investigate the antimicrobial properties, and the results showed inhibition of 50% for Escherichia coli (E.coli) and 55% for Bacillus subtilis (B.subtilis) over 48 h of incubation time. Subsequent in-situ modification of silica nanoparticles like layer on ZnO nanorods-coated ACC surface was developed and used as an electrode for brackish water desalination in a capacitive deionization system. ZnO–SiO2 modified ACC surface enhanced the desalination efficiency by 1.6 times, the salt removal rate (SRR) by threefold, and the durability (fouling prevention) for long-term usage compared to pristine ACC. Further modification of the ZnO–SiO2-ACC surface using fluoropolymer rendered the surface superhydrophobic and oleophilic. Vegetable (1.4 g/g) and crude oil (1.6 g/g) adsorption capacities were achieved for modified surface which was 70% enhancement compared with pristine ACC. The dynamic oil spill adsorption test exhibited the complete removal of oil spills on water surfaces within a few seconds, suggesting a potential application in oil spill cleaning.

Study on the SO2 adsorption performance of dual-layer activated carbon cloth cathode air filter for high-power fuel cell

The removal of SO2 contaminant from the cathode air is crucial for the improvement of the efficiency of high-power fuel cell. The SO2 adsorption behaviour of dual-layer activated carbon cloth (ACC) was investigated at 5–15 ppm SO2 and filtration velocities of 0.125–0.45 m/s. The adsorption amount increased following a power function with time. The equilibrium breakthrough rate declines from approx. 88% to 56% when the concentration drops from 20 ppm to 5 ppm at 0.26 m/s and reduces from approx. 81% to 59% as the filtration velocity decreases from 0.45 m/s to 0.125 m/s at 10 ppm of SO2. In comparison to the packed bed filter, the pressure drop per thickness of the ACC media was considerably lower, measuring less than 9 Pa/mm, which can effectively decrease the parasitic power of the air supply unit. To determine filter’s breakthrough time and adsorption amount for the real application condition, a prediction method coupling the Yoon-Nelson model and the adsorption amount prediction model has been developed. The model can predict the breakthrough time and the adsorption amount of the full-scale filter using low-cost performance test data from the ACC materials with less than 10% error.

Electrochemical sulfur-doping as an efficient method for capacitance enhancement in carbon-based supercapacitors

Cost-efficient fabrication of electrochemical supercapacitors can herald high-capacity energy storage devices. In this work, a simple electrochemical sulfur doping in activated carbon (AC) is introduced, where the specific capacitance of the electrochemically sulfur-doped (ECD) supercapacitor is increased significantly from 147 to 440 F g−1 at 1 A g−1. Surface characterizations, especially high-resolution transmission electron microscopy (HR-TEM), energy-dispersive X-ray spectroscopy (EDAX), and Fourier transform infrared spectroscopy (FTIR) confirm induced sulfur element in the carbon electrode after doping, as result of which the electrochemical measurement shows an increase of the specific capacitance. Moreover, a high energy density of ∼15 Wh kg−1 at 1 A g−1 and almost 90 % capacitance retention at 20 A g−1 after 5000 cycles is achieved. In addition, joint density functional theory (JDFT) is used for the rational design and verification of high-energy-density supercapacitors, supporting our experimental observations. This result paves the way toward further investigations on acid-assisted elemental doping of AC materials for energy storage devices.

Electrochemical Analysis and Quantification of Anodic Oxidation on Activated Carbon Cloth Electrodes through Cyclic Voltammetry

Capacitive Deionization (CDI) has applications ranging from water purification to biofuels processing. For CDI to be a viable scalable technology, electrode stability is critical. In extended experiments the activated carbon cloth (ACC), used for the electrode, has been previously observed to degrade as a result of surface oxidation reactions. Carbon cloth oxidation can reduce the surface area and alter the pore structure, in turn reducing the adsorption capacity. While the behavior of oxidation is known, a reliable method of quantifying the extent of degradation is lacking. To quantify it, cyclic voltammetry was explored to measure the capacitance of pristine and oxidized carbon cloth samples. A three-electrode electrochemical cell was used to quantify capacitance of activated carbon cloth in 1M NaCl solution. The specific capacitance of carbon cloth that underwent anodic oxidation was lower than cathodic and pristine carbon cloth. Further tests analyzed the change in the severity of the anodic degradation on whether the initial CDI separations were performed on organic or inorganic ions. Scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS) was utilized to verify and quantify surface oxidation. Cyclic voltammetry is demonstrated as a simple and reliable method for analyzing and quantifying anodic oxidation on activated carbon cloth electrodes in CDI stacks.

Manganese and Nitrogen Doped Biomass-Based Activated Carbons As Electrocatalysts for Oxygen Reduction and Water Splitting

In this study, an efficient manganese (Mn) and nitrogen (N) co-doped carbon materials were prepared using the three raw materials, namely alder charcoal (Mn-N-CAC), hydrothermally carbonised birch wood (Mn-N-CW), and black liquor (Mn-N-CBL). At first, biomass-based activated carbon materials were synthesized. Mn and N were co-doped in one step using the reaction mixture containing Mn2+ ions source, activated carbon material, and dicyandiamide (DCDA) in dimethylformamide (DMF). DMF was evaporated and the mixture was treated for 60 min at a temperature of 800 ºC. The specific surface area, morphology, structure, and composition of Mn-N-C were determined using BET, TEM, XPS, Raman, XRD, and ICP-OES. Activity of resulted Mn-N-C materials was evaluated for oxygen reduction (ORR) as well as for hydrogen and oxygen evolution (HER and OER) using linear-sweep voltammetry (LSV) with a rotating disk electrode (RDE) in alkaline media.It was found that all Mn-N-C materials had a high specific surface area in the range of approximately of 1800 to 2200 m2 g-1 but the Mn-N-CBL presented a higher contribution of the mesopores in comaparison to Mn-N-CAC and Mn-N-CW which are similar. All synthesized Mn-N-C materials exhibit excellent electrocatalytic activity for ORR with the onset and half-wave potentials of approximately 0.88‒0.90 and 0.80‒0.84 V, respectively, showing the 4e‒ electrons transfer path in 0.1 M KOH solution. The Mn-N-C materials also show enhanced activity for HER and OER in alkaline media. Acknowledgment The “Sustainably Produced Carbon Nanomaterials for Energy Applications (SuNaMa)” benefits from a 988000 € grant from Iceland, Liechtenstein, and Norway through the EEA Grants. The aim of the project is to develop innovative, high-performance, highly conductive, electrocatalytically active, durable, cost-effective, and high surface area nanocarbon materials. Project contract with the Research Council of Lithuania (LMTLT) No. is S-BMT-21-12 (LT08-2-LMT-K-01-055).

Step Potential Electrochemical Spectroscopy (SPECS) Technique to Investigate the Ageing of Carbon Electrodes in Organic-Based Electrochemical Capacitors

Current research on electrode degradation in electrochemical capacitors (ECs) mainly focuses on the application of new materials and the establishment of their stability on the basis of various standards and qualitative tests. However, there exists limited research that focuses on the elucidation and determination of the degradation mechanisms and pathways of carbon electrodes. The proposed study uses an innovative approach with the use of the Step Potential Electrochemical Spectroscopy (SPECS) technique, which allows one to quantify the contribution of different charge-storing mechanisms, and successfully track any changes that take place after accelerated ageing, including structural changes of the electrode in the organic medium. Additionally, the role of oxygen content on the degradation of ECs was explored.In this report carbon material, namely binder-free Activated Carbon Cloth (ACC) Kynol® 507-20 was prepared in a furnace under a nitrogen atmosphere at different temperatures, namely 120, 500, and 1000ᵒC. This is so that the effect of the presence of different oxygen functional groups on the surface of carbon could be investigated. The material was selected as a self-standing electrode to eliminate any influence the binder would have on the electrode porosity. Subsequently, these materials were prepared as electrode materials and assembled in a symmetric two-electrode setup with 1M TEABF4/AN (tetraethylammonium tetrafluoroborate in Acetonitrile solvent). In each cell, the potential range of both electrodes was first determined in a 2-electrode Swagelok® cell with RE using galvanostatic charge/discharge (1 A g-1). The further procedure involved 3 CV cycles (1 mV s-1) at a predetermined potential for each electrode in a 3-electrode set-up, followed by SPECS measurement where 5-minute potentiostatic hold with 10 mV potential steps was applied. The obtained current vs. time plots were used to calculate the corresponding capacitance, diffusion and residual parameters. Floating tests at 2.7 V were then carried out for each system. According to the international standard (IEC 62391-1), system failure is reported when the initial capacitance drops below 80% of its initial value; thus floating experiments were halted after that value was reached for each system or when the resistance of the cell doubled in value. The electrochemical investigation of the individual aged electrodes was then repeated in the same manner.Our study allowed for a thorough examination of individual electrodes prior to and after floating experiments, which helped to elucidate the degradation causes and pathways in organic medium.