Performance Of Activated Carbon Research Articles

An enhanced electrochemical energy storage performance based on porous activated carbon and hard carbon derived from natural maple leaf

The recent development of the nanostructured electrode materials with a large porous carbon structure assures the next-generation material for the high-energy storage application. Herein, we report hard carbon (HC), and activated carbon (AC) materials from natural maple leaf derived. A facilely synthesized zinc chlorate presence and non-presence maple leaf were prepared for the pyrolysis temperature of 800 °C under the nitrogen atmosphere. Various analytical techniques investigated the as-prepared HC and AC samples. The HC and AC modified electrode performances were analyzed using cyclic voltammetry (CV) and galvanostatic charge/discharge in the presence of 6.0 M KOH electrolyte. The most efficient AC and HC performance derived from maple leaves shows the specific capacitance values of 217 F g−1 and 118 F g−1, respectively. The AC-modified electrode showed a promising candidate for high energy storage performance for a practical application.

Lignin Based Activated Carbon Using H3PO4 Activation.

Activated carbon (AC) with a very high surface area of over 2000 m2/g was produced from low sulfur acid hydrotropic lignin (AHL) from poplar wood using H3PO4 at a moderate temperature of 450 °C (AHL-AC6). ACs with similar surface areas were also obtained under the same activation condition from commercial hardwood alkali lignin and lignosulfonate. Initial evaluation of AC performance was carried out using nitrogen adsorption-desorption and dye adsorption. AHL-AC6 exhibited the best specific surface area and dye adsorption performance. Furthermore, the adsorption results of congo red (CR) and methylene blue (MB) showed AHL-AC6 had greater adsorption capacity than those reported in literature. The dye adsorption data fit to the Langmuir model well. The fitting parameter suggests the adsorption is nearly strong and near irreversible, especially for MB. The present study for the first time provided a procedure for producing AC from lignin with Brunauer–Emmett–Teller (BET) surface area >2000 m2/g using low cost and low environmental impact H3PO4 at moderate temperatures.

Recirculating coking by-products and waste for cost-effective activated carbon (AC) production and its application for treatment of SO2 and wastewater in coke-making plant

Utilization of coke-making by-products/wastes and purification of waste gas and wastewater are critical issues for the coke-making industry. Activated carbon (AC) is effective in the removal of various pollutants from gas to aqueous solutions. This paper proposes a feasible and cost-effective approach to produce AC by recirculating coking by-products and waste for pollutants removal in coke-making plant. The results show that AC’s physiochemical structure and its performance could be regulated by altering the coke powder (C) and benzene residue (B)’ addition. Simultaneously addition of C and B slightly promotes AC’s graphitization and has no obvious effect on surface functional groups, and the mechanism was proposed. The sulfur capacity declined obviously with the addition of C and slightly increased with B’s addition, which indicates that about 20% by-products and waste’s addition could achieve similar performance of unmodified AC (51.2 mg/g). As-prepared AC with C and B’s addition could retain coking wastewater’s color and COD removal ability. The engineering practice and implications elucidate the advances and challenges associated with attaining practical, economical, eco-friendly AC production and environmental protection. The objective of this investigation is to explore a scientific basis for better coking by-products and waste utilization and provide an economic sustainability approach through achieves carbon cycle in coking plant for pollutant treatment.

Carbon nanocomposite electrodes for electrical double layer capacitor

Abstract Activated carbons (ACs) have been used as electrode material in commercial electric double-layer capacitors (EDLC) due to their low cost, high specific surface area, and chemical stability. Unfortunately, the supercapacitive performance of AC is not satisfactory due to their low conductivity.On the other hand, carbon nanofibers (CNFs) based EDLC exhibit low equivalent series resistance (ESR) but not such energy storage values as AC ones. Here in this paper, we report on the synthesis of new nanocomposites based on a mixture of ACs and CNFs using a simple powder processing route and evaluating their electrochemical behavior as electrode materials in symmetric EDLC. The EDLC, with 10 wt. % CNFs in AC/CNFs as the electrodes have displayed a high conductivity and surface area resulting in the enhancement of the energy and power delivers in aqueous electrolyte. On the contrary, with 90 wt.% CNFs in AC/CNFs as the electrodes, higher specific power, low ESR, and low value of relaxation time constant are achieved. The highest value of specific capacitance estimated is around 207 F g−1 at 5 mV s−1 and the highest specific energy is 13.2 Wh kg−1 at 1 A g−1 for the 10 wt.% CNFs in AC/CNFs.

Optimizing microwave-assisted production of waste-based activated carbons for the removal of antibiotics from water

This work aimed at the microwave-assisted production of activated carbon (AC) from primary paper mill sludge (PS) for the adsorption of antibiotics from water. Production conditions, namely pyrolysis temperature, pyrolysis time and activating agent (KOH):PS ratio, were optimized as a function of product yield, specific surface area (SBET), total organic carbon (TOC) content and adsorptive removal percentage of two target antibiotics (amoxicillin (AMX) and sulfamethoxazole (SMX)). Under the optimized conditions (pyrolysis at 800 °C during 20 min and a KOH:PS ratio of 1:5), a microporous AC (MW800-20-1:5, with SBET = 1196 m2 g−1, TOC = 56.2% and removal of AMX and SMX = 85% and 72%, respectively) was produced and selected for further kinetic and equilibrium adsorption studies. The obtained results were properly described by the Elovich reaction-based kinetic model and the Langmuir equilibrium isotherm, with maximum adsorption capacities of 204 ± 5 mg g−1 and 217 ± 8 mg g−1 for AMX and SMX, respectively. Considering the satisfactory comparison of these results with the performance of commercial and alternative AC produced by conventional pyrolysis, this work demonstrated the feasibility of the microwave-assisted production of environmentally and energetically sustainable waste-based AC to be applied in the efficient removal of antibiotics from water.

Effect of dispersant on the synthesis of cotton textile waste-based activated carbon by FeCl2 activation: characterization and adsorption properties.

Considering the accumulation and high consumption of activating agents, anhydrous ethanol (AE) could be used to dissolve them to improve the dispersion effect, which was an effective way of improving the practical utilization rate. In this study, FeCl2 was dissolved in AE and further impregnated cotton textile waste (CTW) to prepare activated carbons (ACs) by pyrolysis. Afterward, ACs prepared in optimal conditions determined by the orthogonal experiment evaluated the physicochemical properties and adsorption capacities for Cr(VI). The results illustrated that AE greatly increased the dispersion of FeCl2 on CTW, reduced the conventional impregnation dosage, and remarkably improved the activation efficiency. Textural analyses revealed that ACs exhibited excellent porosity properties and graphite carbon structure. FeCl2 catalyzed the decomposition of volatile substances to produce gaseous products and promoted the transformation of amorphous carbon to graphite carbon that was conducive to pore development, followed by the formation of developed micropores and crystal structures. The adsorption performance of ACs was estimated using Cr(VI), and the adsorption was fitted with the pseudo-second-order kinetic and the Langmuir isotherm. Furthermore, the ACs possessed superior magnetization and reusability. Graphical abstract.

Exploring the factors that influence the adsorption of anionic PFAS on conventional and emerging adsorbents in aquatic matrices

Per and polyfluoroalkyl substances (PFASs) have raised great concern due to their ubiquity in aquatic environments, and adsorption technologies are among the most promising treatment solutions. This study investigated the key factors that influence the adsorption of anionic PFASs on conventional and emerging adsorbents. Batch adsorption experiments were conducted to evaluate the removal of 20 target PFASs at environmentally relevant concentrations by three different activated carbon (AC) materials and two different β-cyclodextrin polymers (CDPs). Experiments were conducted in Milli-Q water and in groundwater. Major physical properties of the adsorbents were measured, along with general water chemistry parameters for each groundwater sample. Principal component analysis (PCA) was subsequently employed to extract the important associations from the multivariate dataset. The distinct performances of ACs and CDPs were attributed to their different surface chemistry and the distinct nature of their adsorption binding sites. Hydrophobic interactions dominated PFAS adsorption onto ACs while CDPs mostly attracted anionic PFASs via favorable electrostatic interactions. ACs of a smaller average particle size performed better, with our data pointing to an increased external specific surface area as the likely reason. pH and the concentration of cations were the primary contributors to adsorption inhibition in groundwater. Higher pH values limit anionic PFAS adsorption by deprotonating the functional groups on adsorbent surfaces. The elevated levels of cations in some groundwater samples limited the effects of attractive electrostatic interactions. Knowledge of PFAS adsorption mechanisms gained from this study can be used to design more efficient adsorbents and to predict their performance under a range of environmental scenarios.

Role of the air-water interface in removing perfluoroalkyl acids from drinking water by activated carbon treatment

Contamination of drinking water by per- and polyfluoroalkyl substances (PFASs) is a worldwide problem. In this study, we for the first time revealed the role of the air-water interface in enhancing the removal of long-chain perfluoroalkyl carboxylic (PFCAs; CnF2n+1COOH, n ≥ 7) and perfluoroalkane sulfonic (PFSAs; CnF2n+1SO3H, n ≥ 6) acids, collectively termed as perfluoroalkyl acids (PFAAs), through combined aeration and adsorption on two kinds of activated carbon (AC). Aeration was shown to enhance the removal of long-chain PFAAs through adsorption at the air-water interface and subsequent adsorption of PFAA-enriched air bubbles to the AC. The removal of selected long-chain PFAAs was increased by 50–115 % with the assistance of aeration, depending on the perfluoroalkyl chain length. Aeration is more effective in enhancing long-chain PFAA removal as air-water interface adsorption increases with PFAA chain length due to higher surface activity. After removing adsorbed air bubbles by centrifugation, up to 80 % of the long-chain PFAAs were able to desorb from the sorbent, confirming the contribution of the air-water interface to the adsorption of PFAAs on AC. Aeration during AC treatment of water could enhance the removal of long-chain PFAAs, and improve the performance of AC during water treatment.

Production of activated carbons from four wastes via one-step activation and their applications in Pb2+ adsorption: Insight of ash content.

Natural biomass is a renewable source for precursors of porous carbon. Four agriculture wastes of corn cob (CC), wheat bran (WB), rice husk (RH), and soybean shell (SS) were applied to produce activated carbons (ACs) via one-step activation by sodium hydroxide. The effects of ash contents and NaOH dosage ratio (1-5) on surface area for ACs were investigated. Owing to ash etching, the high ash precursor (like RH) exhibited less alkali consumption and larger surface area than low ash one (like CC). All four ACs expressed developed pore structure and outstanding surface area of ∼2500m2g-1. During adsorption of lead ions in simulated wastewater, RH-based AC revealed superior capture capacity of 492±15mgg-1. One-step activation had the potential to deliver savings around 1/3 of energy consumption, enabling the cost performance of high ash RH-based AC reaching 194±12gPb2+$-1, 76% larger than low ash CC-based AC. High ash biomass is a promising candidate to obtain eco-friendly carbon products.

Role of inherent pyrite in coal on physicochemical structure of activated carbon and adsorption capacity

Pyrite is the most common inorganic iron-bearing mineral in coal. In order to reveal the influence of inherent pyrite on physicochemical structure and adsorption performance of AC, in this study, different content of pyrite (0.5%, 1%, 2%, 3%) were physically mixed with Yangcheng coal and briquetted, carbonized and steam activated for activated carbon (AC) preparation. As-obtained ACs’ morphology, pore texture, carbon crystallite structure and surface chemistry were characterized by SEM, BET, XRD and FTIR, respectively. The results show that pyrite (FeS2) transformed into hematite (Fe2O3) during AC preparation. Pyrite promotes the interaction between water vapor and carbon and enhances the rate of gasification reactivity by inhibiting the growth of heavy aromatic structures, catalyzing the graphitization process and enhancing the surface chemical properties. The total specific area and specific surface area of micropore of 2%FeS2/AC are up to 836 m2/g and 644 m2/g, which are 58.6% and 46.9% higher than AC, respectively. The 2 h sulfur capacity of 2%FeS2/AC is up to 65.2 mg/g, which is 18.8% greater than that of AC (54.9 mg/g), the mechanism of which was proposed: absorbed gaseous SO2 finally transformed into H2SO4 in macropores and forming an acid macro-environment where most Fe2O3 attacked by the generated H2SO4 on the AC’s pore surface to form Fe2(SO4)3. Fe3+ can promote the oxidation of SO3 to form H2SO4, and a redox cycle of Fe2+ and Fe3+ was established. Moreover, 1%FeS2/AC shows the highest Rhodamine B (RhB) adsorption, and the capacity of RhB is 168 mg/g, which is 41.2% higher than that of AC.

Utilization of activated carbon as an effective replacement for a commercialized three-bed sorbent (Carbopack) to quantitate aromatic hydrocarbons in ambient air

The potential use of activated carbon (AC) as an inexpensive and effective alternative sorbent material in thermal desorption is presented and validated for the analysis of aromatic volatile organic compounds (VOCs) such as benzene, toluene, m-xylene, and styrene (BTXS) in air. The optimum desorption conditions of an AC sampling tube (2 mg AC bed) were determined and compared with a commercial three-bed (Carbopack; C + B + X) tube sampler as a reference. The AC sampler exhibited good linearity (R2 > 0.99) and reproducibility (RSE of 2.38 ± 0.21%) for BTXS analysis. The AC tube sampler showed good storability (up to 3 d) and excellent recyclability (up to 50 cycles). An analysis of BTXS in ambient air showed excellent agreement between AC and CBX (bias < 5%). The 1% breakthrough volume values for 2 mg AC, when tested at 100 ppb of benzene as a sole component or in a BTXS mixture, were 10,000 or 5000 L g−1, respectively. The results of this study support the performance of AC as a suitable medium for sampling VOCs as reliable as high-cost commercial sorbent products.

Different mechanisms between biochar and activated carbon for the persulfate catalytic degradation of sulfamethoxazole: Roles of radicals in solution or solid phase

Biochar as a carbonaceous material alternative to activated carbon (AC) has received increasing application in the catalytic degradation of organic pollutants. However, the different underlying mechanism between biochar and AC for the catalytic degradation is still unclear. In this study, two biochar produced from the pyrolysis of peanut shell at 400 °C (BC400) and 700 °C (BC700) were used to assist persulfate (PS) catalytic degradation of sulfamethoxazole (SMX), a commercial AC was included as a comparison. Results showed that BC700 had a comparable high catalytic degradation performance to AC (88.7% vs 91.2%) but less effective degradation was observed for BC400 (30.4%). Strong sulfate radicals and hydroxyl radials contributed to the higher catalytic abilities of BC700 and AC, as evidenced by Electron Paramagnetic Resonance analysis. Degradation of SMX by BC700 + PS system mainly happened in solution (53.1%) with the relatively complete degradation. High sorption and dominance of radicals in solid phase of AC (84.3%) was responsible for the faster catalytic performance of AC, but incomplete degradation was observed. Density functional theory calculations confirmed that S-N bond adjacent to the S atom in SMX was the susceptible site for radical’s attack. Our findings provide new insight into the different catalytic mechanisms for different carbon materials, which is helpful for the specific carbon materials designed for antibiotics wastewater treatment.

Experimental and DFT study on the adsorption of VOCs on activated carbon/metal oxides composites

To enhance the interfacial interaction of activated carbon (AC) with volatile organic compounds (VOCs), the AC surface was modified by depositing metal oxide nanoparticles via an evaporation-induced self-assembly (EISA) method. Taking acetone, toluene and methanol as adsorbates, both dynamic and static VOCs adsorption methods were used to evaluate the adsorption performance of AC and AC/MOx (M = Mg, Zn, Cu and Zr). Compared to pure AC, metal oxide nanoparticles deposition effectively increased the adsorption capacity for acetone and methanol, and AC/ZnO composites showed the best adsorption performance for acetone (415 mg g−1) and methanol (481 mg g−1). In concert with the experiment, a set of systematic theoretical calculations, regarding adsorption energy, adsorption equilibrium distance and charge transfer, were performed to explore the VOCs adsorption mechanism on the metal oxide surface. The adsorption performance can be determined by the Lewis acid-base properties of VOCs-metal oxide systems, the characteristic functional groups and the molecular polarity of VOCs molecules, which paves a new way to develop a novel metal oxide based adsorbent for the VOCs adsorption applications.

Adsorption and decomposition of tar model compounds over the surface of gasification char and active carbon within the temperature range 250–800 °C

The carbonaceous products of gasification or pyrolysis (chars) and active carbon (AC) have been found effective as adsorbents for tar species and active as catalysts for tar conversion. However, a deeper understanding of the interaction between aromatic compounds and carbonaceous surfaces is needed for the practical implementation and optimization of carbon–based gas cleaning systems. The aim of this work is to investigate the performance of various wood-derived chars and AC within a wide temperature range (250–800 °C). Residual char from gasification, pyrolysis char and two types of AC were tested for their capability to remove tar model compounds (toluene and naphthalene) from a gaseous flow. A dedicated setup was used for this purpose, while post-experimental characterization revealed the modifications occurring at the surface of chars. Adsorption was observed in the lower temperature range, whereas cracking reactions were found to initiate at 600 °C and to become significant at 800 °C. Results suggested that AC represents a better option for tar adsorption applications (e.g. carbon filters) operating at temperatures of 250 °C and possibly below, whereas gasification residual char resulted as the most promising substrate for tar cracking at temperatures of 800 °C and above.

Impact of dissolved organic matter on mercury and methylmercury sorption to activated carbon in soils: implications for remediation.

Activated carbon (AC) amendments have shown promise in reducing inorganic mercury (Hg(ii) complexes, "Hg") and methylmercury (MeHg) risk in contaminated soils. However, the effectiveness of AC in Hg and MeHg immobilization has varied among studies, suggesting that site biogeochemistry might dictate efficacy. In this study, we examined the effect of dissolved organic matter (DOM) on MeHg and Hg sorption to AC. We evaluated the impact of Suwannee River Humic Acid (SRHA) on sorption to AC directly using an isotherm approach and in a soil/AC mixture using slurry microcosms. Aqueous sorption coefficients to AC (log KAC) for Hg-SRHA and MeHg-SRHA complexes were one to two orders of magnitude lower (Hg-SRHA = 4.53, MeHgSRHA = 4.35) than those for chloride complexes (HgCl2 = 6.55, MeHgCl = 4.90) and more closely resembled the log KAC of SRHA (3.64). In anoxic, sulfidic soil slurries, the KAC for sulfide species appeared stronger than for chloride or SRHA species for both Hg and MeHg. AC significantly reduced porewater concentrations of both ambient MeHg and a fresh Me199Hg spike, and the addition of up to 60 mg L-1 SRHA did not reduce sorption to AC. The AC also reduced ambient Hg and 201Hg porewater concentrations, but as SRHA concentration increased, the magnitude of solid phase sorption decreased. Speciation modeling revealed that SRHA may have impacted Hg distribution to the solid phase by reducing HgS precipitation. This study highlights the need for site-specific evaluation of AC efficacy and the value in developing biogeochemical models of AC performance for Hg control.

Fe3O4-CeO2 loaded on modified activated carbon as efficient heterogeneous catalyst

A novel Fe3O4-CeO2/activated carbon (AC) composite was synthesized by an immersion-precipitation process. The Fe3O4-CeO2/AC composite was characterized by BET surface area measurement, Fourier Transform infrared (FTIR), X-ray diffraction (XRD), scanning electron microscope (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopic (XPS), and vibrating sample magnetometer (VSM). Its catalytic activity was evaluated by azo organic dye Orange G (OG) oxidation in heterogeneous Fenton system. Due to excellent performance of AC in adsorption and conductivity, the catalyst exhibited enhanced catalytic activity compared with AC-Fe3O4, CeO2-AC, Fe3O4-CeO2 and AC. Some parameters, such as initial concentration of OG, pH, catalyst loading, H2O2 dosage, were studied. At pH 2.5, H2O2 18 mM, OG 50 mg L−1, Fe3O4-CeO2/AC 0.4 g L−1 and 35 °C, the OG removal rate and the total organic carbon (TOC) removal reached 98.8% and 56.3% within 60 min. The stability and reusability of the Fe3O4-CeO2/AC were also tested. Besides a possible OG degradation pathway was proposed and eight intermediates were determined.

Removal of cationic dye by high surface activated carbon prepared from biomass (date pits) by carbonization and activation processes

In this work,we investigated the capacity of activated carbon (AC) to adsorb Methylene Blue (MB) from aqueous solution. AC-H 3 PO 4 and AC-ZnCl 2 was obtained from date pits via a one-step chemical method using H 3 PO 4 and ZnCl 2 as activating agents. The performance of AC was characterized by different analyses techniques: proximate analysis, SEM, XRD and FT- IR and TGA. The experiments results showed that the MB removal increased by increasing each of AC-H 3 PO 4 and AC-ZnCl 2 concentration, contact time and temperature. The efficiency of the adsorption tests are evaluated by the Langmuir and Freundlich isotherm models. Equilibrium data fitted well by Freundlich modelwith a maximum of the adsorption capacity of 95 mg/g at 333 K for AC-ZnCl 2 , However, the adsorption was well adapted to the Langmuir isotherm with a maximum of the adsorption capacity of 125 mg/g at 298 K for AC-H 3 PO 4 . The kinetics data was explained by the pseudo second-order model, and the intra-particle diffusion with some other rate controlling steps has been suggested as the adsorption mechanism. The pseudo-second-order model described better the adsorption process. The thermodynamic study suggested that MB adsorption on AC-ZnCl 2 was endothermic, spontaneous and non-spontaneous for AC-H 3 PO 4 .

Removal Effect of Atrazine in Co-Solution with Bisphenol A or Humic Acid by Different Activated Carbons.

Activated carbons (ACs) based on apricot shells (AS), wood (W), and walnut shells (WS) were applied to adsorb atrazine in co-solutions. To study the effect of Bisphenol A (BPA) on the adsorption behavior of atrazine, the adsorption performance of ACs for BPA in single solution was studied. The results demonstrated that the adsorption kinetics of BPA fitted the pseudo-second-order model, the adsorption isotherms of BPA followed the Langmuir model. Meanwhile, the adsorption kinetics of atrazine fitted the pseudo-second-order kinetics model and the isotherm was consistent with the Freundlich model both in single solution and co-solution. In addition, competitive adsorption was observed when atrazine coexisted with BPA or humic acid. For the adsorption capacity, the adsorption amount of ASAC, WAC, and WSAC for atrazine obviously decreased by 18.0%, 30.0%, and 30.3% in the presence of BPA, respectively, which was due to the π−π interactions, hydrophobic interactions, and H-bonds, resulting in the competitive adsorption between atrazine and BPA. This study contributes to the further understanding of the adsorption behavior for atrazine in co-solution.

Effect of the Feedstock Type on the Volumetric Low-Pressure CO2 Capture Performance of Activated Carbons

Activated carbons (ACs) display attractive gravimetric performance for CO2 capture, but it is unclear which carbon precursor suits preparation of ACs with high adsorption performance on a volumetric basis. Thus, we prepared ACs from five feedstocks (bamboo, rice husk, peanut shell, coconut shell, and anthracite) to study impacts of the feedstock type on the densities, volumetric pore parameters, and volumetric CO2 adsorption performance of ACs. The feedstock type was found to affect tap density of ACs, mainly because ACs possessed different macropore volumes. Because of the influence of tap density, the decreasing order of ACs for volumetric pore parameters was different from that for the corresponding gravimetric parameters. When AC was expected to display a high volumetric fine micropore volume (V<0.7 nm,v and V<1 nm,v), its tap density and gravimetric fine micropore volume should be both high. The feedstock type affected the volumetric CO2 uptakes of ACs at 0.15 and 1 bar, mainly because it changed vol...

Effects of activation temperature on densities and volumetric CO2 adsorption performance of alkali-activated carbons

Activated carbons (ACs) prepared by chemical activation were promising materials for CO2 capture, but how to adjust their densities and volumetric CO2 adsorption performance is unclear. We prepared ACs from petroleum coke by KOH activation to study impacts of activation temperature (540–820 °C) on densities and volumetric CO2 adsorption performance of ACs. As the activation temperature increased, the true density rose whereas the apparent density and tap density decreased. The true density of ACs was dominated by aromatic-carbon ratio, not by the previously-believed graphitization degree. The activation temperature required to achieve the maximum volumetric low-pressure CO2 uptake was lower than that needed to attain the highest gravimetric value (540 °C < 610 °C). When an AC was expected to display a high volumetric CO2 adsorption capacity, its tap density and gravimetric CO2 uptake should be moderate at least. The volumetric CO2/N2 selectivity decreased with increasing activation temperature, mainly because of widening of micropore size distribution. This study provided new insights into ACs' densities, and highlighted judging ACs for CO2 capture by the previously-overlooked volumetric adsorption performance rather than only by the commonly-used gravimetric performance.