Preparation Of High Surface Area Research Articles

Production and evaluation of activated carbon from Saudi Arabian Acacia Tortilis tree bark by microwave and low temperature activation process

In the present work, activated carbon was prepared from Acacia Tortilis tree bark, utilizing phosphoric acid chemical activation, and microwave irradiation (AC-MWI). Activated carbon was also prepared by conventional phosphoric acid chemical activation and low temperature carbonization (AC-CA). Characterization of the activated carbons were performed by proximate analysis adopting ASTM standard procedures. BET-specific surface area, total ash content, bulk density, moisture content, pH, pore volume and iodine number were determined. Comparison of characteristics for both carbons, with the characteristics of AC available in the literature and commercially available in the market was performed. Comparison showed that activated carbon produced from Acacia Tortilis tree bark is well comparable with the reported characteristics of AC in literature and commercially available in market. It was found that AC-MWI has higher BET-specific surface area than AC-CA (836 m2/g and 687 m2/g respectively). Results depict that there is an increase of 22.3% in microspores component and 21.7% BET- specific surface area obtained in AC-MWI as compared to AC-CA. Similarly, the corresponding pore volume obtained (4.97 cm3/g and 4.07 cm3/g respectively) demonstrating better values as compared to the commercial ACs (<1 cm3/g). Additionally, it was found that AC can be produced by microwave irradiation in about 48.5% less time when compared to conventional low temperature heating. The adsorption study of produced ACs was performed using methylene blue as a contaminant. Study showed that MB removal rate initially increased with increase in contact time, which decreased with time until steady state was reached. Adsorption data of MB was fitted to Freundlich, Langmuir and Temkin adsorption isotherm models. All models show reasonable correlation, however, Freundlich isotherm is best to describe the MB adsorption on AC-MWI based on correlation coefficient R2 value (0.9985). The results revealed the feasibility of microwave heating for preparation of high surface area activated carbons from Acacia Tortilis tree bark.

Production and evaluation of activated carbon from Saudi Arabian Acacia Tortilis tree bark by microwave and low temperature activation process

In the present work, activated carbon was produced from Acacia Tortilis tree bark, utilizing phosphoric acid chemical activation, and microwave irradiation (AC-MWI). Activated carbon was also produce by conventional phosphoric acid chemical activation and low temperature carbonization (AC-CA). Characterization of produced activated carbons performed by proximate analysis adopting ASTM standard procedures. BET-specific surface area, total ash content, bulk density, moisture content, pH, pore volume and iodine number were determined. Comparison of characteristics for both carbon, with the characteristics of AC available in the literature and commercially available in the market was performed. Comparison showed that activated carbon produced from Acacia Tortilis tree bark is well comparable with the reported characteristics of AC in literature and commercially available in market. It was found that AC-MWI has higher BET-specific surface area than AC-CA (836 m2/g and 687 m2/g respectively). Results depict that there is an increase of 22.3% in microspores component and 21.7% BET- specific surface area obtained in AC-MWI as compared to AC-CA. Similarly, the corresponding pore volume obtained (4.97 cm3/g and 4.07 cm3/g respectively) demonstrating better values as compared to the commercial ACs (<1 cm3/g). Additionally, it was found that AC can be produced by microwave irradiation in about 48.5% less time when compared to conventional low temperature heating. The adsorption study of produced ACs was performed using methylene blue as a contaminant. Study showed that MB removal rate initially increased with increase in contact time, which decreased with time until steady state was reached. Adsorption data of MB was fitted to Freundlich, Langmuir and Temkin adsorption isotherm models. All models show reasonable correlation, however, Freundlich isotherm is best to describe the MB adsorption on AC-MWI based on correlation coefficient R2 value (0.9985). The results revealed the feasibility of microwave heating for preparation of high surface area activated carbons from Acacia Tortilis tree bark.

High Surface Area “3D Graphene Oxide” for Enhanced Sorption of Radionuclides

AbstractHere preparation of high surface area activated reduced graphene oxide (arGO) oxidized into a 3D analogue of defect‐rich GO (dGO) is reported. Surface oxidation of arGO results in carbon to oxygen ratio C/O = 3.3, similar to the oxidation state of graphene oxide while preserving high BET surface area of about 880 m2 g−1. Analysis of surface oxidized arGO shows high abundance of oxygen functional groups which converts hydrophobic precursor into hydrophilic material. High surface area carbons provide the whole surface for oxidation without the need of intercalation and lattice expansion. Therefore, surface oxidation methods are sufficient to convert the materials into 3D architectures with chemical properties similar to graphene oxide. The “3D graphene oxide” shows high sorption capacity for U(VI) removal in an extraordinary broad interval of pH. Notably, the surface oxidized carbon material has a rigid 3D structure with micropores accessible for penetration of radionuclide ions. Therefore, the bulk “3D GO” can be used as a sorbent directly without dispersing, the step required for GO to make its surface area accessible for pollutants.

Maximizing Energy Density of Nanostructured Electrochemical Capacitors: From Proof of Concept to Reliable Manufacturing

Currently, portable energy storage devices are lacking in the overall performance characteristics needed to meet desired energy and power density performance demands. Furthermore, these performance demands for long-lasting energy storage devices for portable electronics continue to constantly increase. Batteries remain the main source of portable energy storage, but they generally lack the pulsed-power delivery capability required by many applications, as well as have limited cycle life. Thus, improvements in devices that show a high operational cycle life in addition to delivering high energy and power densities are extremely desirable over a wide range of physical sizes, footprints, and power delivery capabilities. Conventional electrostatic capacitors provide some of these benefits compared to batteries, including high power density and extended cycle life, but are lacking in the energy density capability required to replace batteries in many applications.Electrochemically-based double-layer capacitors (EDLCs) or ultracapacitors offer a promising solution to bridging the gap between maintaining the high-power density capability of electrostatic capacitors while providing a path to improving the energy density to be comparable to batteries –significantly broadening their applicability. An EDLC’s power density and energy density are based on the highly reversible surface charge adsorption-based mechanism of energy storage. This provides benefits in terms of high frequency responses as well as providing a route to supply power for longer duration pulses. Additionally, since the stored capacity is based on the surface charge adsorption-based energy storage, it provides an essentially indefinite lifespan as long as the materials do not degrade. However, current EDLC technologies still provide significantly lower energy density than is available from batteries. This energy density gap must be narrowed if the EDLCs are going to make further inroads toward replacing batteries.The capacitance and energy density are driven by the electrode’s available solution-accessible surface area. Thus, our approach to increasing the energy density of electrochemical capacitors is through the development of carbon nanotube-based electrode structures with a precise, highly controlled and ordered nanostructured porosity. To further improve power and energy density, these electrode structures are used in combination with an ionic liquid electrolyte with high voltage window, thus providing an increased operating voltage. While traditional electrode materials are generally comprised of randomly ordered porous structures, we have developed electrodes with an adjustable and highly controlled pore structure that provide very high surface area. These electrodes are produced using a nanotemplated approach that allows for preparation of high surface area aligned and vertically oriented carbon nanotube (CNT)-based electrodes. The templated approach has the added benefit of a achieving a greater areal CNT density than available in traditional carpet-grown CNT forests as well as providing more uniform and controllable CNT outer and inner diameters. The ability to control these dimensions allows for tailoring the electrode geometry for a specific electrolyte.Ionic liquids are becoming increasingly popular in a variety of applications as a result of their unique properties and highly tailorable chemistry. In electrochemical applications, their large voltage stability window, low vapor pressure, excellent thermal stability at temperatures above most organic solvents’ boiling points, and lower temperature conductivity make them an excellent electrolyte choice. Ionic liquids are ideal for use in higher temperature electronics applications, especially in small-scale microelectronics formats where confined spaces make efficient heat removal very difficult. By making use of ionic liquid electrolytes and optimizing the interaction of the electrolyte with our templated CNT electrodes, we have developed an energy storage technology with high-energy density and high-power density.In this talk, we will discuss the challenges and solutions to scaling up the fabrication and testing of reproducible, nanostructured electrodes from 3.14 cm2 or smaller single-sided lab cells to multiple 200 cm2 electrodes on both sides of an aluminum current collector. We will discuss the electrode fabrication scale-up and performance validation from small coin or disc cells tested in a glove box to larger area sealed pouch cells with integration of an optimized ionic liquid electrolyte. We discuss cell fabrication challenges and solutions including verifying the performance of the electrodes as they are scaled up, and the cell fabrication including ensuring the electrode and separator are reliably wetted with the ionic liquid electrolyte. The challenges of optimizing the practical tradeoff of electrode active depth and minimizing the current collector thickness as we move the electrode and overall cell design to a fully packaged cell while maintaining the optimized electrochemical performance characteristics will be discussed.[DISTRIBUTION STATEMENT A. Approved for public release; Distribution is unlimited 412TW-PA-21154]

Preparation of high surface area Cu‐Au bimetallic nanostructured materials by co‐electrodeposition in a deep eutectic solvent

Our sustainable future requires finding new, affordable and green routes to prepare nanostructured materials used in renewable energy conversion. In this work we present an electrodeposition method in a deep eutectic solvent (DES) to prepare bimetallic high surface area nanostructures of Cu and Au with tunable structure and composition. The metal electrodeposition performed in choline chloride within a urea deep eutectic solvent allows us to tailor the size, morphology and elemental composition of the deposits. We combine electrochemical methods with scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDS) to characterize the electrodeposited nanostructured materials. We assess the increase of the electroactive surface area through the analysis of the lead underpotential deposition (UPD) on the prepared films. Integrated Pb UPD charge values of ca. 1600–4000 μC/cm2 for the prepared Cu-Au films have been calculated, suggesting a 5–14 fold increase of the active surface area compared to flat surfaces of polycrystalline Cu or Au. Our work reports a versatile and environmentally friendly route for the electrodeposition of Cu-Au bimetallic nanostructures in a DES. The combination of a tailored morphology and composition with the high active surface area of the nanostructured materials show that electrodeposition in DES is promising for the development of multimetallic electrocatalysts.

Pseudo Continuous Reactor with Microwave-plasma for Preparation of High Surface Area Activated Carbon

Pseudo Continuous Reactor with Microwave-plasma for Preparation of High Surface Area Activated Carbon

Preparation of High Surface Area Oxidized Activated Carbon from Peanut Shell and Application for the Removal of Organic Pollutants and Heavy Metal Ions

A peanut shell-derived oxidized activated carbon (OAC) with high surface area was prepared by zinc chloride (ZnCl2) chemical activation and subsequent nitric acid oxidation. OAC was characterized by scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR), and N2 adsorption-desorption. The results showed that OAC had the surface area of 1807 m2 g−1, with the total pore volume of 0.725 cm3 g−1 and average pore diameter of 3.8 nm. More importantly, when OAC acted as an adsorbent, it exhibited high efficiency to remove basic blue 41 (BB-41), congo red (CR), phenol, Cr(VI), and Pb(II) from aqueous solution due to its universality in adsorption. Batch adsorption experiments were carried out to study the effect of various parameters such as pH, initial concentration, temperature, and contact time. Also, the isotherms, kinetic models, and thermodynamics of adsorption process were investigated. The equilibrium data for CR and Pb(II) were fitted to Langmuir isotherm model, while Freundlich model was suitable for the equilibrium isotherm of BB-41, phenol, and Cr(VI), respectively. As the result indicated, peanut shell was a suitable raw material to synthesize OAC which could be employed as an efficient and universal adsorbent for removing organic pollutants and heavy metal ions from wastewater.

Preparation of high surface area and high conductivity polyaniline nanoparticles using chemical oxidation polymerization technique

In this work, polyaniline nanoparticles were synthesized using a chemical oxidation polymerization technique. The ammonium peroxydisulfate (APS)/aniline ratio, APS dropping time, and polymerization temperature were optimized to increase the surface area and conductivity of the polyaniline.The Fourier-transform infrared (FTIR) spectrum confirmed the formation of emeraldine salt polyaniline. X-ray diffraction (XRD) patterns indicated that amorphous and crystalline phases of the polyaniline were formed with crystallinity less than 40%. Scanning electron microscope (SEM) micrographs showed that the finest nanoparticles with uniform size distribution were obtained at the polymerization temperature of 0°C. A surface area analyzer (SAA) showed that the highest Brunauer-Emmett-Teller surface area (SBET) of 42.14 m2/gwas obtained from an APS/aniline ratio of 0.75 with a dropping time of 0 s at a polymerization temperature of 0°C. A four-point probe measurement conducted at 75–300K indicated relatively high conductivity of the semiconductor characteristic of the polyaniline.

Preparation of high surface area activated carbon from waste-biomass of sunflower piths: Kinetics and equilibrium studies on the dye removal

Sunflower pith (SP), a vast agricultural waste is herein used as a precursor material for highly porous low density activated carbon production. Porosity and flake-like microstructure of the SP in its natural form are shown by micro-computed tomography (Micro-CT). Carbonization process turns the SP into thin, separated carbon flakes of 200 nm thickness. Two types of alkaline based chemical activation with KOH and NaOH are performed to yield SP based activated carbon (AC), K-SPAC and N-SPAC, respectively. Microstructural changes upon carbonization and activation process are elaborated by RAMAN, FTIR and SEM analyses. BET Surface area of the NaOH-activated N-SPAC was calculated as 2690 m2/g and was higher than KOH-activated K-SPAC with 2090 m2/g. Maximum adsorption capacity of N-SPAC was calculated as 965 mg/g whereas it was 580 mg/g for K-SPAC. Adsorption kinetic studies for N-SPAC revealed that at a low initial concentration of dye (500 mg/L), the pseudo first-order kinetic model was predictive. On the other hand, at high initial MB concentration (1000 mg/L), the results indicate that the adsorption kinetics follow the Elovich model with intraparticle diffusion as one of the rate-determining steps.In conclusion, overall results suggest that thanks to its highly porous microstructure, the SP is an alternative renewable AC precursor choice for dye removal applications.

Preparation of High Surface Area Activated Carbon from Spent Phenolic Resin by Microwave Heating and KOH Activation

AbstractThe spent phenolic resin is as raw material for preparing high surface area activated carbon (HSAAC) by microwave-assisted KOH activation. The effects of microwave power, activation duration and impregnation ratio (IR) on the iodine adsorption capability and yield of HSAAC were investigated. The surface characteristics of HSAAC were characterized by nitrogen adsorption isotherms, FTIR, SEM and TEM. The operating variables were optimized utilizing the response surface methodology (RSM) and were identified to be microwave power of 700 W, activation duration of 15 min and IR of 4, corresponding to a yield of 51.25 % and an iodine number of 2,384 mg/g. The pore structure parameters of the HSAAC, i. e., Brunauer–Emmett–Teller (BET) surface area, total pore volume, and average pore diameter were estimated to be 4,269 m2/g, 2.396 ml/g and 2.25 nm, respectively, under optimum conditions. The findings strongly support the feasibility of microwave-assisted KOH activation for preparation of HSAAC from spent phenolic resin.

Preparation of high surface area Ni/MgAl2O4 nanocatalysts for CO selective methanation

Methanation of carbon monoxide in the H2-rich gas stream was performed on a series of the Ni/MgAl2O4 catalysts in a fixed bed micro-reactor. The catalysts were synthesized using wetness impregnation method and the prepared samples were characterized by XRD, BET, SEM, TEM, H2-TPR, CO chemisorption and CO-TPD techniques. The catalyst carrier was prepared by a novel sol-gel method using nitrate salts precursors and propylene oxide as a gelation agent. MgAl2O4 as catalyst carrier possessed a high BET area of 340 m2 g−1 with high pore volume (0.563 cc g−1) and small pore size (6.56 nm). The catalysts also showed high BET area, which decreased with the increase in Ni content. These catalysts exhibited mesoporous structure with average nickel crystal size smaller than 20 nm. The catalyst with Ni content of 25 wt% exhibited the maximum CO conversion and CH4 selectivity and can be considered as a catalyst with high catalytic potential for the selective methanation of carbon monoxide.

High surface area, amorphous titania with reactive Ti3+ through a photo-assisted synthesis method for photocatalytic H2 generation

A facile approach for the preparation of high surface area, Ti3+ containing titania with good activity for photocatalytic H2 production is reported.

Precipitation Preparation of High Surface Area and Porous Nanosized ZnO by Continuous Gas-Based Impinging Streams in Unconfined Space

Using the precipitation method, we propose a new process for the preparation of high specific surface area and large pore volume ZnO nanoparticles in unconfined space with NH4HCO3 and ZnSO4·7H2O as the reactants. The mixing performance of the reaction system was improved by gas atomization and continuous gas-based impinging streams before the precipitation reaction. By virtue of the gas environment and gas division, the obtained nanoparticles have a very good dispersion performance. Under optimal conditions, the ZnO nanoparticles were synthesized with a surface area of 88.89 m2/g, an average diameter of 7 nm, and a pore volume of 0.68 cm3/g. The influences of ZnSO4 concentration, pressure, and gas–liquid ratio on the properties of the synthesized nanoparticles were studied. This study aims to provide a feasible and economical way to produce better properties in nanosized ZnO particles, which are widely applied as a new, multifunctional material.

Effect of Microwave Heating Conditions on the Preparation of High Surface Area Activated Carbon from Waste Bamboo

Abstract The present study reports the effect of microwave power and microwave heating time on activated carbon adsorption ability. The waste bamboo was used to preparing high surface area activated carbon via microwave heating. The bamboo was carbonized for 2 h at 600°C to be used as the raw material. According to the results, microwave power and microwave heating time had a significant impact on the activating effect. The optimal KOH/C ratio of 4 was identified when microwave power and microwave heating time were 700 W and 15 min, respectively. Under the optimal conditions, surface area was estimated to be 3441 m2/g with pore volume of 2.093 ml/g and the significant proportion of activated carbon was microporous (62.3%). The results of Fourier transform infrared spectroscopy (FTIR) were illustrated that activated carbon surface had abundant functional groups. Additionally the pore structure is characterized using Scanning Electron Microscope (SEM).

Preparation of high surface area activated carbon from Eupatorium adenophorum using K2CO3 activation by microwave heating

AbstractThe present study attempts to utilize

Preparation of High Surface Area Activated Carbon from Elaeagnus angustifolia Seeds by Chemical Activation with ZnCl2 in One-Step Treatment and its Iodine Adsorption

The present study was conducted with the preparation of activated carbon through one-step chemical activation using zinc chloride (ZnCl2) as the activating agent from Elaeagnus angustifolia seeds (EAS). The effect of impregnation ratio, activation temperature, and activation time on activated carbon surface area was discussed. The properties of activated carbon were characterized by N2 adsorption (BET), thermogravimetric analyses (TGA), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR). The best conditions for preparing activated carbon were identified to be temperature of 500°C, impregnation ratio of 150%, impregnation time of 48 h, and activation time of 60 min with BET surface area of 1836 m2/g. The adsorption capacity was demonstrated by the iodine numbers.

Preparation of High Surface Area Ce/La/Cu and Ce/La/Ni Ternary Metal Oxides as Catalysts for the SO2 Reduction by CH4

In this work, CeO2–La2O3–CuO and CeO2–La2O3–NiO catalysts were prepared based on the Taguchi L16 experimental design method. The synthesized catalysts were characterized by Scanning electron microscopy, BET, XRD, N2 adsorption isotherm, and BJH pore size distributions. The maximum obtained surface areas for these catalysts were 99.4 and 72.3 m2/g, respectively. The related average crystal size of the above catalysts from XRD tests was about 6.8 nm. The prepared optimum catalysts were tested for SO2 reduction by CH4. The SO2 conversion and sulfur yields at various temperatures were compared between optimized copper and nickel ternary oxide catalysts. The copper catalyst showed better performance at moderate temperatures, while at high temperatures the nickel catalyst exhibited better performance.

Utilization of oil palm biodiesel solid residue as renewable sources for preparation of granular activated carbon by microwave induced KOH activation

In this work, preparation of granular activated carbon from oil palm biodiesel solid residue, oil palm shell (PSAC) by microwave assisted KOH activation has been attempted. The physical and chemical properties of PSAC were characterized using scanning electron microscopy, volumetric adsorption analyzer and elemental analysis. The adsorption behavior was examined by performing batch adsorption experiments using methylene blue as dye model compound. Equilibrium data were simulated using the Langmuir, Freundlich and Temkin isotherm models. Kinetic modeling was fitted to the pseudo-first-order, pseudo-second-order and Elovich kinetic models, while the adsorption mechanism was determined using the intraparticle diffusion and Boyd equations. The result was satisfactory fitted to the Langmuir isotherm model with a monolayer adsorption capacity of 343.94mg/g at 30°C. The findings support the potential of oil palm shell for preparation of high surface area activated carbon by microwave assisted KOH activation.

A facile and green preparation of durian shell-derived carbon electrodes for electrochemical double-layer capacitors

A facile and green preparation of high surface area activated carbons with mixed microporosity and mesoporosity from durian shell waste is reported in this work. The pore structure and surface chemistry of the parent carbon were modified by the combination of ultrasonication and microwave irradiation techniques. The effects of temperature and time in the ultrasonication treatment and power output and time in the microwave irradiation were studied. The electrochemical performance of carbon electrodes for supercapacitors was tested by cyclic voltammeter (CV) and galvanostatic charge–discharge. The results show that the capacitive energy storage of electrodes is critically dependent on the microporosity and surface chemistry of activated carbons. The highest electrode capacitance in this work was 103.6F/g that prepared from activated carbon modified at an ultrasonication temperature of 323.15K for 10min and microwave power output of 900W for 10min.

Preparation of high surface area, graphitic porous carbon monolith using magnetite nanoparticles as catalyst and porogens

A method to prepare monolithic porous graphitic carbon with high surface area was investigated using nanosize monodispersed magnetite particles(~10 nm) as graphitization catalysts and a porogen template,and an oligomer derived from the polymerization of 2,4-dihydroxybenzoic acid with formaldehyde catalyzed by sodium carbonate as carbon source.The magnetite/oligomer composites were carbonized at 700-900 ℃ under a nitrogen atmosphere to generate graphitized carbon composites.Finally,monolithic porous graphitic carbon was obtained after HCl treatment to remove the iron-based particles.Results show that carbonization temperature has a great influence on the graphitization degree and the Brunauer-Emmett-Teller(BET) surface area of the resultant products.The BET surface areas decreased and the graphitization degree of the products increased with carbonization temperature from 700 to 900 ℃.At a low carbonization temperature of 700 ℃,the templating effect of the magnetite particles(as porogens) can be clearly observed.Highly graphitic carbon with a high surface area can be obtained at 800 ℃.