Activated Carbon Materials Research Articles

Анализ особенностей аппаратурно-технологического оформления процесса высокотемпературной активации углеродного материала

The relevance of research in the development of activated carbon materials with a high specific surface area and porosity, which can be used as materials for the separation or storage of various liquid and gaseous media, is shown. A plurality of approaches to the implementation of the activation process is noted, characterized mainly by the accumulation of experimental data and laboratory studies. The process of high-temperature activation of carbon material was studied using the synergistic effect of two activators on the activated material. The features of the flow of this process and the relationship between the regime parameters and the design of the equipment are established. The characteristics of the obtained activated carbon material, namely the parameters of the specific surface area and porosity, are analyzed. Solutions are proposed aimed at reducing the ambiguity in the design of hardware and technological design of the high-temperature activation process.

Four-step constant voltage operation of hybrid capacitive deionization with composite electrodes for bifunctional deionization and lithium recovery

Efficient recovery of valuable resources from wastewater has emerged as a critical challenge in the era of carbon neutral society. Capacitive deionization (CDI) has been employed in electrochemical lithium recovery (ELR) processes based on selective Li+ intercalation to LiMn2O4 (LMO). We herein propose a four-step constant voltage operation (forward/zero/reverse/zero) of bifunctional hybrid CDI to produce deionized water as well as Li+-rich concentrate within a cycle. Especially, selective Li+ enrichment was possible without influent replacement since adsorption of competing ions and liberation of Li+ could occur simultaneously. This unique performance was enabled by composite electrodes on capacitive activated carbon cloth (ACC) impregnated with redox-active materials; LMO@ACC and Ag@ACC. Together with material characterization and electroanalysis on the composite electrodes, deionization (step 1; forward voltage) and Li+ enrichment (step 3; reverse voltage) by assembled LMO@ACC//Ag@ACC cell were evaluated by single pass experiments with binary NaCl and LiCl solution (10 mM each). Besides, a multi-stage operation with internal recycle confirmed long-term stability and continuous increase of Li purity for practical implementation. The advanced bifunctional CDI (ELR coupled with water treatment) paved a way to advance the resource recycle from wastewater.

One-step synthesis of a sustainable carbon material for high performance supercapacitor and dye adsorption applications

The sustainable transformation of bio-waste into usable, material has gained great scientific interest. In this paper, we have presented preparation of an activated carbon material from a natural mushroom (Suillus boletus) and explor its properties for supercapacitor and dye adsorption applications. The produced cell exhibited a single electrode capacitance of ∼247 F g−1 with the energy and power density of ∼35 Wh kg−1 and 1.3 kW kg−1, respectively. The cell worked well for ∼20,000 cycles with ∼30% initial declination in capacitance. Three cells connected in series glowed a 2.0 V LED for ∼1.5 min. Moreover, ultrafast adsorption of methylene blue dye onto the prepared carbon as an adsorbent was recorded with ∼100% removal efficiency in an equilibrium time of three minutes. The performed tests indicate that the mushroom-derived activated carbon has the potential to become a high-performance electrode material for supercapacitors and an adsorbent for real-time wastewater treatment applications.

Adsorption of Hydrogen Sulfide on Activated Carbon Materials Derived from the Solid Fibrous Digestate.

The goal of this work is to develop a sustainable value chain of carbonaceous adsorbents that can be produced from the solid fibrous digestate (SFD) of biogas plants and further applied in integrated desulfurization-upgrading (CO2/CH4 separation) processes of biogas to yield high-purity biomethane. For this purpose, physical and chemical activation of the SFD-derived BC was optimized to afford micro-mesoporous activated carbons (ACs) of high BET surface area (590-2300 m2g-1) and enhanced pore volume (0.57-1.0 cm3g-1). Gas breakthrough experiments from fixed bed columns of the obtained ACs, using real biogas mixture as feedstock, unveiled that the physical and chemical activation led to different types of ACs, which were sufficient for biogas upgrade and biogas desulfurization, respectively. Performing breakthrough experiments at three temperatures close to ambient, it was possible to define the optimum conditions for enhanced H2S/CO2 separation. It was also concluded that the H2S adsorption capacity was significantly affected by the restriction to gas diffusion. Hence, the best performance was obtained at 50 °C, and the maximum observed in the H2S adsorption capacity vs. the temperature was attributed to the counterbalance between adsorption and diffusion processes.

Tailored Properties of Carbon for Supercapacitors by Blending Lignin and Cellulose to Mimic Biomass as Carbonaceous Precursor.

KOH-activated carbon materials prepared from biomass-derived carbon source, cellulose and lignin, were compared. Mixtures of different ratios of cellulose and lignin were used to partially mimic biomass as carbon source. This allows tailoring and optimizing of the KOH activated carbon materials by getting rid of the restriction of the intrinsic proportion of cellulose and lignin in specific biomass. The results indicate that cellulose use results in a more porous structure, whereas lignin use leads to more partially activated graphite structure. The activated carbon material (CL1) prepared from blend of cellulose with lignin in mass ratio of 1 : 1 exhibits a high specific surface area of 2000.39 m2 g-1 , and in TEABF4 /ACN (tetraethylammonium tetrafluoroborate dissolved in acetonitrile) electrolyte it showed a maximum specific capacitance of 136.10 F g-1 , a maximum energy density of 18.11 Wh kg-1 , and a capacitance retention of 85.04 % under current density as high as 15 A g-1 .

Low-temperature hydrothermal carbonization of activated carbon microsphere derived from microcrystalline cellulose as carbon dioxide (CO2) adsorbent

Activated carbon material produced by the low-temperature hydrothermal processes was needed to further decrease the production cost of CO2 adsorbent materials. In this study, we fabricated cellulose hydrochar microspheres (CHM) materials with a relatively low hydrothermal temperature (200 °C) with prolonged hydrothermal reaction time (48 h) using microcrystalline cellulose as a feedstock. The CHM is then further activated using a thermal and chemical agent. The activated carbon microsphere was then characterized using scanning electron microscopy (SEM), an X-ray diffractometer (XRD), and Fourier transforms infrared (FTIR) spectroscopy. The Brunauer–Emmett–Teller (BET) surface area (SBET) of the thermal activation (ACS) activated carbon was enhanced significantly with further chemical activation with KOH and NaOH, from 589 m2/g to 1334 m2/g and 2296 m2/g, respectively. Moreover, CHONS elemental analysis suggests that the chemical activation process enhances the surface functional group. Increasing textural properties and enrichment of the functional group of the ACS-NaOH and ACS-KOH samples gave a CO2 adsorption capacity up to 7.07 mmol/g after 300 min of contact. This finding enables the possibility of producing cellulose hydrochar microspheres using a low hydrothermal temperature that can be further activated to become CO2 adsorbent materials with great CO2 capture capabilities.

Influence of humidity on activated carbon fabrics scheduled for use in high sensitivity radon detectors

The dependence of radon adsorption on the content of adsorbed water of activated carbon fabrics of ACC-5092-10 and ACC-5092-20 was studied experimentally. Specimens with different content of adsorbed water (from zero to saturation level) were coupled with alpha-track detector and exposed to reference 222Rn concentration. Both materials demonstrated different properties: Radon adsorption in ACC-5092-10 smoothly and monotonically decreases with the increase of adsorbed water and at saturation level it is lower by a factor of 2.5 as compared to the fully dehydrated material. In ACC-5092-20 clear break point was observed at water content of about 20% where radon adsorption sharply drops by a factor of 15. ACC-5092-10 was identified as a material that keeps its high radon adsorption ability even when saturated with water. Coupled with alpha-track detector it may be used for sensitive long-term measurements 222Rn measurements even at high levels of humidity.

Hindered diffusion of heavy metal cations in the adsorption rate on activated carbon fiber

Water resource pollution caused by heavy metals represents a risk to the environment because of their toxicity. Adsorption on activated carbon materials can be applied to remove heavy metals in aqueous solutions. Activated carbon fiber (ACF) is a microporous material successfully used for adsorbing heavy metals from water solutions; however, the adsorption rate on ACF has yet to be investigated in detail. The adsorption equilibrium and rate of Cd(II), Ni(II) and Zn(II) on ACF were analyzed in this study, and the experimental data were procured in a differential packed bed batch adsorber. The Radke-Prausnitz isotherm successfully interpreted the experimental adsorption equilibrium data. The adsorption rate was analyzed employing a diffusional model, supposing that the external mass transfer along with intraparticle or intrafiber diffusion affect the overall adsorption rate. Besides, the metal intrafiber diffusion was attributed exclusively to diffusion in the pores volume, excluding surface diffusion. The results revealed that intrafiber diffusion is significantly affected by hindered diffusion caused by frictional effects on pore walls (Kr), steric exclusion (Kp), and blocking provoked by metal cations adsorbed onto pore walls (Ka). The hindrance factors Kr and Kp were estimated using literature correlations, and Ka was related to the mass of metal adsorbed.

Proton-self-doped PANI@CC as the cathode for high-performance aqueous zinc-ion battery

Aqueous zinc-ion batteries (AZIB) have several advantages such as low cost, large theoretical capacity and good safety. However, the development of polyaniline (PANI) cathode materials has been limited by slow diffusion kinetics. Herein, proton-self-doped polyaniline@carbon cloth (CC) (PANI@CC) was prepared via in-situ polymerization, where polyaniline was deposited on an activated carbon cloth. The PANI@CC cathode exhibits a high specific capacity of 234.3 mA h g−1 at 0.5 A g−1, and excellent rate performance, delivering a capacity of 143 mA h g−1 at 10 A g−1. Furthermore, the reversible redox conversion during the charge–discharge process was studied using ex-situ X-ray photoelectron spectroscopy (XPS) and ex-situ Raman spectra. The results show that the excellent performance of the PANI@CC battery can be attributed to the formation of a conductive network between the carbon cloth and polyaniline. Also, a mixing mechanism involving insertion/extraction of Zn2+/H+ and a double-ion process is proposed. PANI@CC electrode is a novel idea for developing high-performance batteries.

High mass loading and additive-free prussian blue analogue based flexible electrodes for Na-ion supercapacitors

Supercapacitor electrodes often suffer from the low mass loading of active substances and the unsatisfactory ion/charge transport features due to the use of various additives. Exploring high mass loading and additive-free electrodes is of huge significance to develop advanced supercapacitors with commercial application prospects, which still remains challenging. Herein, high mass loading CoFe-prussian blue analogue (CoFe-PBA) electrodes are developed by a facile co-precipitation method using activated carbon cloth (ACC) as the flexible substrate. The homogeneous nanocube structure, large specific surface area (143.9 m2 g−1) and appropriate pore size distribution (3.4 nm) of the CoFe-PBA endow the as-prepared CoFe-PBA/ACC electrodes with low resistance and appealing ion diffusion characteristics. Typically, the high areal capacitance (1155.0 mF cm−2 at 0.5 mA cm−2) is obtained for high mass loading CoFe-PBA/ACC electrodes (9.7 mg cm−2). Furthermore, symmetrical flexible supercapacitors (FSCs) are constructed using CoFe-PBA/ACC electrodes and Na2SO4/polyving alcohol (Na2SO4/PVA) gel electrolyte, achieving superior stability (85.6% capacitance retention after 5,000 cycles), maximum energy density of 33.8 μWh cm−2 at 200.0 μW cm−2 and promising mechanical flexibility. This work is expected to offer inspirations for the development of high mass loading and additive-free electrodes for FSCs.

Stimulation of the metal doping process of nanoporous carbon material by laser irradiation

It has been established that the doping of activated carbon material with chromium and manganese increases the specific capacitance of storage devices based on the charge-discharge mechanism of a double electric layer (DEL) by ~70 % and leads to a decrease in their internal resistance by 30-35 %. The main reason for this rise is the transformation of the electron energy spectrum due to an increase in the density of electronic states, as a result of which a much larger number of electrolyte ions (primarily positive ones) participate in the formation of DEL and cause an increase in the specific capacitance of these devices. It has been shown that laser irradiation stimulates the metal penetration into the bulk of carbon material.

Removal behaviors of phenol from aqueous solution using industrial coal sludge-derived porous carbon sorbent

Porous activated carbon was prepared from industrial coal sludge (CS) by one-step pyrolysis and KHCO3 activation, and applied to remove phenol from aqueous phase. The effects of activation parameters on the characteristics of activated carbon and phenol adsorption performance were investigated. CSAC-900 (obtained at 900 °C) has abundant pores and shows three-dimensional porous structure. The adsorption process of phenol on CSAC-900 are controlled by various mechanisms, such as π-π interaction, hydrogen bond and pore filling. The isotherm fitting agrees with Langmuir model. The maximum adsorption capacity of phenol on CSAC-900 is 305.83 mg/g. The positive ΔH and negative ΔG illustrate the adsorption of phenol onto CSAC-900 is a spontaneous endothermic reaction. Compared with commercial activated carbon materials, the adsorption of phenol by CSAC-900 exhibits significant advantages in adsorption capacity and adsorption rate, and it can also be regenerated and recycled.

Synthesis and evaluation of metal-impregnated carbon cloth supplementation to improve anaerobic digestion performance from municipal sludge

This study investigated the effect of metal-impregnated carbon cloth (CC) supplementation on thermophilic anaerobic digestion (AD) improvement by utilizing municipal sludge as a biomass input. Four types of metal-impregnated CC nanocomposites (Fe/CC, Ni/CC, Ni/Fe/CC, NiPcS/Fe/CC) were synthesized from activated CC (A-CC) using hydrothermal synthesis and compared with untreated CC (U-CC) to evaluate their functional significance for enhanced AD. The main factors inspected were electrical conductivity (EC) and Brunauer–Emmett–Teller (BET) surface area. A-CC had the highest surface area of 386.15 m2/g, followed by Fe/CC, NiPcS/Fe/CC, Ni/CC and Ni/Fe/CC with 140.96, 52.27, 43.52 and 36.07 m2/g, respectively. The A-CC and Fe/CC reactors produced 3.45 and 2.70 times more methane than Control (without CC) in the first 9 days. In contrast, the methane production for U-CC, Ni/CC, Ni/Fe/CC and NiPcS/Fe/CC was only 0.87, 1.26, 1.01 and 1.29 times, respectively, compared to Control. At a higher BET surface (>350 m2/g), the surface area becomes a more dominant factor, and the increase of EC value (>2.9*104 1/Ω.m) does not have an impact on methane enhancement. Microbial community analysis revealed that A-CC had the highest abundances of Syntrophomonas, Coprothermobacter and methanogenic populations, including Methanothermobacter and Methanosarcina, within 3 days compared to Control and metal-impregnated CC. There were minimal changes in microbial community composition in metal-impregnated CC compared to the U-CC. The result implies that the efficacy of CC supplementation for AD upgrading largely depends on the higher surface area compared to metal impregnation or conductivity.

Easy to make highly efficient FG@ACC stable platform for sp3C-CF3 bond generation and NADH regeneration under sun light

The conversion of sun light energy into sustainble greener chemicals are a major obstacle due to the use of expensive and toxic materials. Sun light induced trifluoromethylation emerges as a highly efficient procedure to insert trifluoromethyl groups into the organic compounds. Yet, the expensive and toxic properties of the metal-based photocatalysts creates a major obstacle for the insertion of trifluoromethyl groups. Metal free activated carbon cloth (ACC) emerged as a highly efficient pillar in the area of material science. In this work, we have successfully synthesized self-assembled metal free fast green with activated carbon cloth (FG@ACC) photocatalyst for photocatalytic trifluoromethylation and reduced nicotinamide adenine dinucleotide (NADH) cofactor regeneration (85.89 %, 2 h) under sun light. The sun light induced organic transformation promotes the use of low-cost CF3SO2Na as the CF3 radical source to produce highly selective products with 97% yield.

Activated Carbon Derived from Waste Oil Shale Semi-Coke for Supercapacitor Application.

As fossil fuels gradually deplete, oil shale, one of the world's largest energy resources, has attracted much attention. Oil shale semi-coke (OSS) is the main byproduct of oil shale pyrolysis, which is produced in large quantities and causes severe environmental pollution. Therefore, there is an urgent need to explore a method suitable for the sustainable and effective utilization of OSS. In this study, OSS was used to prepare activated carbon by microwave-assisted separation and chemical activation, which was then applied in the field of supercapacitors. Raman, XRD, FT-IR, TEM, and nitrogen adsorption-desorption were adopted to characterize activated carbon. The results showed that ACF activated with FeCl3-ZnCl2/carbon as a precursor has larger specific surface area, suitable pore size, and higher degree of graphitization compared with the materials prepared by other activation methods. The electrochemical properties of several active carbon materials were also evaluated by CV, GCD, and EIS measurements. The specific surface area of ACF is 1478 m2 g-1, when the current density is 1 A g-1, the specific capacitance is 185.0 F g-1. After 5000 cycles of testing, the capacitance retention rate was as high as 99.5%, which is expected to provide a new strategy of converting waste products to low-cost activated carbon materials for high-performance supercapacitors.

Washable All-in-One Self-Charging Power Unit Based on a Triboelectric Nanogenerator and Supercapacitor for Smart Textiles.

Lightweight, portability, and sustainability have become key factors of the power source for the rapid development of multifunctional wearable electronic devices. In this work, a washable, wearable, and durable self-charging system for human motion energy harvesting and storage based on asymmetric supercapacitors (ASCs) and triboelectric nanogenerators (TENGs) is investigated. The all-solid-state flexible ASC is composed of a cobalt-nickel layered double hydroxide grown on a carbon cloth (CoNi-LDH@CC) as the positive electrode and activated carbon cloth (ACC) as the negative electrode and exhibits the performance of small size, high flexibility, and superior stability. The device was able to provide a capacity of 345 mF cm-2 and a cycle retention rate of 83% after 5000 cycles, which shows great potential as an energy storage unit. Additionally, flexible silicon rubber-coated carbon cloth (CC) is waterproof and soft and can be used as a TENG textile to gain energy for stable charging of an ASC, which presents an open-circuit voltage and short-circuit current of 280 V and 4 μA, respectively. The ASC and TENG can be assembled to continuously collect and store energy, which provides an all-in-one self-charging system qualified with washable and durable for potential applications in wearable electronics.

Integrated MnO2/PEDOT composite on carbon cloth for advanced electrochemical energy storage asymmetric supercapacitors

Advanced flexible supercapacitors with high energy/power density are an imperative research objective. In this study, a dually activated carbon cloth is designed as the functional current collector for supercapacitors. An electrodeposition technique is used for engineering Manganese Dioxide (MnO2) nanoflakes and profiting from a Poly (3,4 ethylene dioxythiophene; PEDOT) shield layer, a Li+-based neutral electrolyte high-performance freestanding asymmetric supercapacitors is constructed. The activated carbon cloth (ACC) provides an efficient electron-carrying route and the hierarchical nanostructure of the ACC@MnO2@PEDOT electrode. The integrated ACC@MnO2@PEDOT electrode exhibited exceptional capacitance performance of 1882.5 mF cm−2 (current density 1 mA cm−2) in 1.5 M aqueous LiCl electrolyte benefiting from ACC scaffold, the pseudocapacitive activity of MnO2 and substantial conductivity of the PEDOT polymer. Fabricating the structured electrode into an asymmetric supercapacitor revealed an enhanced areal energy density and an areal power density. The fabricated device demonstrated a broad voltage window of 1.8 V and extraordinary cycling stability of 94.6% after 10000 charge-discharge cycles. The unique scaffold, conducting PEDOT polymer, and MnO2 nanoflakes synergistically improved the cyclic performance and rate proficiency of the electrode, resulting in a supercapacitor with bendable electrical energy storage applications.

Investigation of the performance of activated carbon cloth to remove glyphosate, glufosinate, aminomethylphosphonic acid and bialaphos from aqueous solutions by adsorption/electrosorption.

The present study investigates the removal of glyphosate, glufosinate, aminomethylphosphonic acid and bialaphos herbicides from their 5 × 10-5M aqueous solutions onto activated carbon cloth by adsorption and electrosorption. Analysis of these highly polar herbicides was achieved by UV-visible absorbance measurements, after derivatization with 9-fluorenylmethyloxycarbonyl chloride. The limit of quantification values of glyphosate, glufosinate, aminomethylphosphonic acid and bialaphos were 1.06 × 10-6mol L-1, 1.38 × 10-6mol L-1, 1.32 × 10-6mol L-1 and 1.08 × 10-6mol L-1, respectively. Glyphosate, glufosinate, aminomethylphosphonic acid and bialaphos were removed from their aqueous solutions with higher efficiencies by means of electrosorption (78.2%, 94.9%, 82.3% and 97%, respectively) than of open-circuit adsorption (42.5%, 22%, 6.9% and 81.8%, respectively). Experimental kinetic data were fitted to pseudo-first order and pseudo-second order kinetic models. It was determined that pseudo-second order kinetic model represents experimental data better with satisfactory coefficient of determination, r2 (> 0.985) and normalized percent deviation, P (< 5.15) values. Adsorption isotherm data were treated according to Freundlich and Langmuir isotherm models. Based on the r2 (> 0.98) and P (< 5.9) values, it was found that experimental data well fitted to Freundlich isotherm model. Adsorption capacities of activated carbon cloth for glyphosate, glufosinate, aminomethylphosphonic acid and bialaphos, expressed in terms of Freundlich constant, were calculated as 20.31, 118.73, 239.33 and 30.68mmolg-1, respectively. The results show that the studied ACC can be used in home/business water treatment systems as an adsorbent due to its high adsorption capacity.

Determination of Atrazine in Food, Water, and Synthetic Urine by Activated Carbon Cloth (ACC) Micro-Solid-Phase Extraction (µSPE) with High-Performance Liquid Chromatography – Diode Array Detection (HPLC-DAD)

Activated carbon cloth (ACC) was used as a micro solid phase extraction (µSPE) sorbent for the separation-preconcentration and determination of atrazine in water, juice, spice, and artificial urine by high-performance liquid chromatography-diode array detector (HPLC-DAD). The adsorbent mass was 10 mg, the adsorption-desorption duration was 90-s, and the proposed method can be applied to different matrices. The preconcentration factor of the method is 16.7. The limit of detection (LOD) and limit of quantification (LOQ) were 0.7 and 2.2 ng mL−1, respectively. The recovery values of the presented procedure were from 93 to 108% for real samples. This µSPE-HPLC-DAD protocol is practical and sensitive for atrazine and shows that activated carbon cloth is a highly effective adsorbent.

Synthesis of Mesoporous Carbon Adsorbents Using Biowaste Crude Glycerol as a Carbon Source via a Hard Template Method for Efficient CO2 Capture.

Biowaste utilization as a carbon source and its transformation into porous carbons have been of great interest to promote environmental remediation owing to biowaste's cost-effectiveness and useful physicochemical properties. In this work, crude glycerol (CG) residue from waste cooking oil transesterification was employed to fabricate mesoporous crude glycerol-based porous carbons (mCGPCs) using mesoporous silica (KIT-6) as a template. The obtained mCGPCs were characterized and compared to commercial activated carbon (AC) and CMK-8, a carbon material prepared using sucrose. The study aimed to evaluate the potential of mCGPC as a CO2 adsorbent and demonstrated its superior adsorption capacity compared to AC and comparable to CMK-8. The X-ray diffraction (XRD) and Raman results clearly depicted the structure of carbon nature with (002) and (100) planes and defect (D) and graphitic (G) bands, respectively. The specific surface area, pore volume, and pore diameter values confirmed the mesoporosity of mCGPC materials. The transmission electron microscopy (TEM) images also clearly revealed the porous nature with the ordered mesopore structure. The mCGPCs, CMK-8, and AC materials were used as CO2 adsorbents under optimized conditions. The mCGPC adsorption capacity (1.045 mmol/g) is superior to that of AC (0.689 mmol/g) and still comparable to that of CMK-8 (1.8 mmol/g). The thermodynamic analyses of the adsorption phenomena are also carried out. This work demonstrates the successful synthesis of a mesoporous carbon material using a biowaste (CG) and its application as a CO2 adsorbent.