Two-step Carbonization Process Research Articles

Utilization of macadamia nutshell-derived activated carbon for enhanced congo red adsorption

This study addresses the challenge of removing Congo red (CR) from aqueous solutions using activated carbon (AC) derived from macadamia nutshells (MNS). A unique two-step carbonization and pyrolysis process was employed to produce MNS-AC with high surface area and porosity. Key experimental variables, including initial CR concentration, contact time, and pH, were systematically varied in batch mode. Results indicated that the modified AC achieved significantly higher removal percentages compared to unmodified charcoal. At pH 2.0 and an initial dye concentration of 50 mg L−1, CR removal reached 97.48 % for MNS-AC3. The maximum adsorption capacity (qmax) of 58.29 mg g−1 was observed at an initial dye concentration of 200 mg L−1. The pseudo-second-order kinetic model closely matched the experimental data, and equilibrium data analysis using Langmuir and Dubinin-Radushkevich (D-R) isotherm models provided excellent fits. This research demonstrates the potential of using industrial biomass waste to develop sustainable solutions for dye removal in wastewater treatment.

Carbon Nanosheet Preparation By Low-Temperature Two-Step Carbonization: A Study of Their Properties and Mechanism of Adsorption of Oxidized H2S.

Straw, as a kind of biomass waste, has the advantages of low cost and abundant storage, which makes it a promising renewable resource. Using rice straw as a carbon source, carbon nanosheets were prepared by a two-step carbonization method combining low-temperature pyrolysis and low-temperature hydrothermal, and they were used as H2S removal agents. The results showed that during the two-step carbonization process, the adsorption performance of carbon nanosheets for H2S showed a tendency of enhancing and then weakening with the increase of pyrolysis temperature in the first step, and the sulfur capacity could reach 3.1 mg/g at the maximum of the pyrolysis temperature of 200 °C, which was superior to or close to that of the modified or activated carbon. The XPS, EPR, and CO2-TPD tests showed that the surface of carbon nanosheets was alkaline, containing a large number of hydroxyl groups and the presence of phenoxy persistent free radicals or semiquinone persistent free radicals. It was analyzed that the direct or indirect oxidation of H2S by the persistent radicals under an alkaline environment could convert the -2-valent sulfur into -1-, 0- and +6-valent sulfur to realize the adsorption and removal of H2S. This work, while offering the possibility of utilizing carbon nanosheets made from straw as a material for H2S adsorption and removal, also expands the application of straw waste in exhaust gas treatment.

N, S co-doped coal-based hard carbon prepared by two-step carbonization and a molten salt template method for sodium storage

Hard carbon, known for its abundant resources, stable structure and high safety, has emerged as the most popular anode material for sodium-ion batteries (SIBs). Among various sources, coal-derived hard carbon has attracted extensive attention. In this work, N and S co-doped coal-based carbon material (NSPC1200) was synthesized through a combination of two-step carbonization process and heteroatom doping using long-flame coal as a carbon source, thiourea as a nitrogen and sulfur source, and NaCl as a template. The two-step carbonization process played a crucial role in adjusting the structure of carbon microcrystals and expanding the interlayer spacing. The N and S co-doping regulated the electronic structure of carbon materials, endowing more active sites. Additionally, the introduction of NaCl as a template contributed to the construction of pore structure, which facilitates better contact between electrodes and electrolytes, enabling more efficient transport of Na+ and electrons. Under the synergistic effect, NSPC1200 exhibited exceptional sodium storage capacity, reaching 314.2 mAh g-1 at 20 mA g-1. Furthermore, NSPC1200 demonstrated commendable cycling stability, maintaining a capacity of 224.4 mAh g-1 even after 200 cycles. This work successfully achieves the strategic tuning of the microstructure of coal-based carbon materials, ultimately obtaining hard carbon anode with excellent electrochemical performance.

Graphene-containing biocarbon from burlap waste: Property comparison with commercial grade graphene nanoplatelets

In this paper, we report a method for synthesizing high-yield graphene-containing biocarbon from burlap waste through a simple two-step carbonization process. The first step involves feedstock carbonization at 600 °C, followed by ball milling and then graphitization at 1200 °C using KOH. A comparative analysis between the obtained bio-graphene and commercial graphene revealed superior graphene properties of the burlap-based graphene. Notably, this bio-based graphene exhibited exceptional characteristics such as a very high BET surface area in the range of 1021 m²/g, low defect-to-graphene ratio of 0.12 in the Raman spectra, and an overall yield of 19% wt. These findings highlight the potential of burlap waste as a sustainable precursor for high-quality graphene synthesis and its potential for various applications.

A highly pyrrolic-N doped carbon modified SiOx anode for superior lithium storage.

The poor interfacial stability and undesirable cycling performance caused by their dramatic volume change hinder the large-scale commercial application of SiOx materials for high-energy-density lithium-ion batteries. Herein, a simple two-step carbonization process is employed to prepare highly pyrrolic-nitrogen-doped carbon modified SiOx anode materials (SiOx@NC). The designed SiOx@NC materials exhibit high electron conductivity and favorable electrochemical kinetics. As expected, the SiOx@NC electrode delivers a high specific capacity of 1003.46 mA h g-1 after 200 cycles at 500 mA g-1. The NCM622||SiOx@NC full cell also demonstrates excellent cycling stability and rate performance.

Preparation of spherical porous carbon from lignin-derived phenolic resin and its application in supercapacitor electrodes

Lignin is the most abundant aromatic biomass resource in nature and is the main by-product of paper industry and biorefinery industry, which has the characteristics of abundant source, renewable and low cost. Deep eutectic solvents (DES) are a nascent environmentally friendly solvent option that is gaining traction. DES composed of p-toluenesulfonic acid and choline chloride is used for batch treatment of alkaline lignin, and the bio-oil obtained is ternary polymerized with formaldehyde and phenol to obtain lignin phenolic resin. The porous carbon material is produced through a two-step carbonization process, utilizing phenolic resin derived from lignin as the primary source of carbon. The morphology and composition of the carbon were analyzed by SEM, TEM, XRD, TGA, XPS and Raman spectroscopy, the specific surface area and pore size distribution were analyzed by BET. The results showed that the specific surface area of the lignin-based phenolic resin was significantly higher than that of the pure phenolic resin carbon, and the porous carbon material that was acquired demonstrated a specific surface area of as much as 1026 m2/g. In the three-electrode system, the specific capacitance of DLPFC can reach 245.8 F/g (0.25 A/g), with a very small decrease in the value of specific capacitance at 10,000 cycles, with a retention of 97.62% (10 A/g). The porous carbon demonstrated a specific capacitance of 112.4 F/g at a current density of 0.5 A/g, and the capacitance retention rate could still reach 98.8% after 5000 charge/discharge cycles, with high cycling stability (in the two-electrode system). The prepared symmetrical supercapacitors exhibited high energy density and power density of 3.9 Wh/kg and 125.0 W/kg. The results suggest a new idea of high value-added application of lignin phenolic resin for high-performance supercapacitor electrodes.

Boosting supercapacitor performance through the facile synthesis of boron and nitrogen co-doped resin-derived carbon electrode material

In this study, we present the synthesis of porous carbon materials designated as B, N co-doped porous carbon materials (PRNB), co-doped with boron and nitrogen through a two-step carbonization process of self-made phenolic resin. Among them, urea, boric acid, and potassium oxalate were used as the heteroatom dopants and activator, respectively. The co-doping of boron and nitrogen induced a unique electronic structure, resulting in improved capacitance performance compared to single-doped materials. Moreover, the addition of potassium oxalate as an activator facilitated the etching of the carbon framework during pyrolysis. Owing to the co-doping effect of boron and nitrogen and the abundant micropores, the PRNB material exhibited a remarkably high specific capacitance of 330 F g−1 at 1 A g−1. It also displayed excellent rate performance (70 %) and stability, with only a 6 % loss after 10,000 cycles compared to other materials. The symmetric electrode based on PRNB achieved an energy density of up to 29.7 Wh kg−1 in a neutral electrolyte, which provides a novel approach for resin-derived carbon to improve electrochemical performance.

Precisely tuning porosity and outstanding supercapacitor performance of phenolic resin-based carbons via citrate activation

Developing a facile, inexpensive, and efficient approach for preparing porous carbon materials with high electrochemical properties is critical to the commercial viability of supercapacitors (SCs). Herein, a novel hierarchical porous carbon with extraordinary SCs performance is developed via a two-step carbonization process by employing low-temperature self-made phenolic resin as raw materials. Therein, the introduction of citrate is the key to generate distinct configurations and obtain high electrochemical properties. Particularly, the potassium citrate and sodium citrate (mass ratio of 3:1) activated sample (RFN-KNa) exhibits large specific surface area (1089.78 m2 g−1), high nitrogen content (2.91 at.%) and outstanding specific capacitance (280 F g−1 at 1 A g−1). Additionally, the RFN-KNa-based symmetric SCs also possesses ultrahigh energy densities, which are found to be 24.79 Wh kg−1 (at 900.1 W kg−1) and 17.42 Wh kg−1 (at 703.4 W kg−1) in 1 M Na2SO4 and 6 M KOH electrolyte, respectively. Meanwhile, the SCs also displays eminent rate capability and cycle stability. This work offers a new insight for preparing hierarchical porous carbon materials and opens up a new avenue for applying resin materials in the field of energy storage.

Electrospun PVDF Membranes Incorporated with Functionalized Carbon-based Material for Removal of Cationic Dyes

In this study, polyvinylidene fluoride (PVDF) polymeric membranes with addition of functionalized carbon-based material (CBM) were fabricated by using electrospinning technique for the removal of cationic dyes from wastewater. CBM was prepared through a two-step carbonization process from cotton linter as an agricultural waste biomass. The characterization of CBM was performed by using Brunauer–Emmett–Teller (BET) surface analysis, fourier transform infrared spectrometry (FTIR) and elemental analysis. The morphologies of electrospun membranes were observed by scanning electron microscope (SEM) which clearly revealed that nanofibers with a smooth surface were produced by incorporation of CBM. According to the results obtained from FTIR and differential scanning calorimetry (DSC), crystallization behavior of PVDF membranes was promoted by increasing the percentage of CBM in the membrane. PVDF membrane prepared with the addition of 3 wt % CBM exhibited the highest water flux performance with a dye rejection of 74.6 % in comparison with the pure PVDF one.

MIL-101(Fe)-derived iron oxide/carbon anode for lithium-ion batteries: Derivation process study and performance optimization

Metal-organic frameworks (MOFs) have attracted extensive attention due to their tunable porosity and abundant metal ions, making them promising precursors for preparing functional materials for energy storage and conversion. Therefore, a study of their derivatization process is important for designing derivatives with specific functional properties. Herein, MIL-101(Fe) was pyrolyzed to prepare iron oxides/carbon composites, and semi-in-situ gas chromatography and in situ powder X-ray diffraction were used to investigate the derivatization process. When evaluated as a lithium-ion battery anode, MIL-101(Fe)-800–400 prepared by a two-step carbonization process exhibited a higher specific capacity than the material prepared by one-step carbonization under N2. The reason for the improved electrochemical properties was explored. This work provides a better understanding of the carbonization process of MOFs, which allows the controllable synthesis of other MOF-based functional materials.

Economically feasible thermochemical process for methanol production from kenaf

This paper presents a thermochemical process design and techno-economic analysis for the production of methanol (MeOH) from Kenaf cultivated in Korea. The proposed process combines three main subsystems to allow for the processing of 2000 tons of kenaf a day: kenaf-to-syngas, syngas-to-MeOH, and a combined heat and power cycle. In the first subsystem, clean syngas is produced from kenaf via a two-step carbonization and steam gasification process. The clean syngas is then catalytically upgraded to MeOH using a commercial Cu/ZnO/Al2O3 catalyst. The third subsystem allows for the generation of heat and electricity to close the energy balance by combusting the biomass residues. Energy analysis and optimization of the heat exchanger network allowed for all energy requirements to be satisfied internally, high overall energy efficiency (60.6%), and the selling of 3.3 MW of excess electricity. Furthermore, an economic feasibility analysis of the process showed that the minimum selling price of MeOH (99.9 wt%) was 0.413 US$/kgMeOH. Importantly, the process economics could be in the range of the market price with respect to incorporating different types of H2 production technology into the process.

Origin analysis and the elimination of the columnar crystal defects in the 3C-SiC/Si (1 0 0) heteroepitaxial layers by the modified two-step carbonization process

New columnar crystal defects were formed on the surface of 3C-SiC epitaxial growth on Si (100) substrates by a modified two-step carbonization process. The density of columnar crystal defects was reduced with the increase in the C/Si mole ratio. However, the defects could not be completely removed, even after increasing the C/Si mole ratio from 0.8 to 2.0. The size of the columnar crystal defects in 3C-SiC epi-layer growth in the SiH4-C3H8-H2 system was around 4 μm, and was unaffected by the C/Si mole ratio. The FIB and TEM investigations showed that the columnar crystal defects originated from the supersaturation of Si vapor. The columnar crystal defect was also present along 〈002〉 orientation and inclined along [111] direction at an angle of about 54.7°. HCl was used to inhibit the homogeneous gas-phase nucleation of Si, which was regarded as the formation introducing a factor of columnar defects. When the Cl/Si mole ratio was increased to 5.0, columnar crystal nucleation was completely suppressed.

Waste cotton fabric derived porous carbon containing Fe3O4/NiS nanoparticles for electrocatalytic oxygen evolution

Developing low-cost, active and durable electrocatalysts for oxygen evolution reaction (OER) is an urgent task for the applications such as water splitting and rechargeable metal-air battery. Herein, this work reports the fabrication of a metal and hetero atom co-doped fibrous carbon structure derived from cotton textile wastes and its use as an efficient OER catalyst. The free-standing fibrous carbon structure, fabricated with a simple two-step carbonization process, has a high specific surface area of 1796 m2/g and a uniform distribution of Fe3O4/NiS nanoparticles (Fe3O4/NiS@CC). The composite exhibits excellent OER performance with an onset potential of 1.44 V and a low overpotential of 310 mV at the current density of 10 mA/cm2 in a 1.0 M KOH solution, which even surpass commercial RuO2 catalyst. Additionally, this ternary catalyst shows remarkable long-term stability without current density loss after continuous operation for 26 h. It can be believed that the outstanding OER performance is attributed to the synergistic effect between the iron oxides and nickel sulphides, as well as the micro-meso porous carbon structure. This study demonstrates a new strategy to use conventional textile materials to prepare highly efficient electrocatalysts; it also provides a simple approach to turn textile waste into valuable products.

Developing Lignosulfonate-Based Activated Carbon Fibers

In this study, electrospinning technology, physical activation, and carbonization processing were applied to produce lignosulfonate-based activated carbon fibers. The porous structure of the produced lignosulfonate-based activated carbon fibers primarily contained mesopores and a relatively small amount of micropores. Moreover, insufficient carbonization caused fiber damage during CO2 activation. The weight loss rate and specific surface area increased with increase in carbonization time, and products with carbonization temperatures of 700 °C were of higher quality than those with other temperatures. Moreover, the two-step carbonization process provided fibers with improved quality because of a low weight loss rate, improved processing, and high surface area. Lignosulfonate-based activated carbon fibers can be used as a highly efficient adsorption and filtration material, and further development of its applications would be valuable.

Atomic Layer Deposition of Ruthenium Nanoparticles on Electrospun Carbon Nanofibers: A Highly Efficient Nanocatalyst for the Hydrolytic Dehydrogenation of Methylamine Borane.

We report the fabrication of a novel and highly active nanocatalyst system comprising electrospun carbon nanofiber (CNF)-supported ruthenium nanoparticles (NPs) (Ru@CNF), which can reproducibly be prepared by the ozone-assisted atomic layer deposition (ALD) of Ru NPs on electrospun CNFs. Polyacrylonitrile (PAN) was electropsun into bead-free one-dimensional (1D) nanofibers by electrospinning. The electrospun PAN nanofibers were converted into well-defined 1D CNFs by a two-step carbonization process. We took advantage of an ozone-assisted ALD technique to uniformly decorate the CNF support by highly monodisperse Ru NPs of 3.4 ± 0.4 nm size. The Ru@CNF nanocatalyst system catalyzes the hydrolytic dehydrogenation of methylamine borane (CH3NH2BH3), which has been considered as one of the attractive materials for the efficient chemical hydrogen storage, with a record turnover frequency of 563 mol H2/mol Ru × min and an excellent conversion (>99%) under air at room temperature with the activation energy ( Ea) of 30.1 kJ/mol. Moreover, Ru@CNF demonstrated remarkable reusability performance and conserved 72% of its inherent catalytic activity even at the fifth recycle.

Conjugated polymer-mediated synthesis of sulfur- and nitrogen-doped carbon nanotubes as efficient anode materials for sodium ion batteries

Heteroatom-doped carbon nanomaterials have attracted significant attention as anode materials for sodium-ion batteries (SIBs). Herein, we demonstrate a conjugated polymer-mediated synthesis of sulfur and nitrogen co-doped carbon nanotubes (S/N-CT) via the carbonization of sulfur-containing polyaniline (PANI) nanotubes. It is found that the carbonization technique greatly influences the structural features and thus the Na-storage behavior of the S/N-CT materials. The carbon nanotubes developed using a two-step carbonization process (heating at 400 °C and then at 900 °C) exhibit a high specific surface area, enlarged interlayer distance, small charge transfer resistance, enhanced reaction kinetics, as well as a large number of defects and active sites; further, they exhibit a high reversible capacity of 340 mAh·g–1 at 0.1 A·g–1 and a remarkable cycling stability with a capacity of 141 mAh·g–1 at 5 A·g–1 (94% retention after 3,000 cycles). Direct carbonization of conjugated polymers with a specific morphology is an eco-friendly and low-cost technique for the synthesis of dual atom-doped carbon nanomaterials for application in energy devices. However, the carbonization process should be carefully controlled in order to better tune the structure–property relationship.

Preparation and Characterization of Nitrogen and Oxygen Heteroatom Codoped Activated Biocarbons from Edamame Shell

A simple procedure was evaluated to prepare cost-effective heteroatom self-doped porous carbons from edamame shell using a two-step carbonization and activation process. The morphological, structural, textural properties and N2/CO2 adsorption–desorption were investigated. The results showed that edamame shell, which is abundant in nitrogen and oxygen, is an ideal precursor for preparing heteroatom self-doped porous carbons. The N and O contents of the prepared activated carbons (ACs) ranged from 1.20 wt% to 1.81 wt% and 5.13 wt% to 9.98 wt%, respectively. Furthermore, the specific surface area of 1835 m2/g of the N and O doped ACs resulted in mainly microporosity, which suggested that it has promising potential for wide applications in the fields of catalysis, energy conversion, energy storage devices, and adsorption.

Heteroatom self-doped activated biocarbons from fir bark and their excellent performance for carbon dioxide adsorption

A series of cost-effective heteroatom-doped porous carbons has been developed from the agricultural by-products of fir bark by a two-step carbonization and activation process. The morphology, chemical characterization and texture properties were investigated by thermogravimetric analysis (TG), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectrometry (XPS), elemental analysis (EA), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM) and N2 adsorption-desorption at 77 K. The results show that fir bark is a suitable precursor for preparing heteroatom-doped activated carbon, corresponding to hetero-oxygen (2.05–7.35 wt. %) and nitrogen (0.8-1.5 wt. %) doping. The lab-made AC materials derived from fir bark, with a surface area of 1377 m2/g, showed a very excellent sorption performance for CO2 up to 7 mmol/g and 5.2 mmol/g at 273 K and 298 K up to 1 bar, which was significantly higher than the commercial carbon materials and were among the highest compared with other biomass based ACs. The high CO2 uptakes, moderate heat of adsorption (Qst), good selectivity show that the high performance activated carbons for CO2 capturing at low pressure can be prepared by KOH activation of fir bark.

Effect of C/Si Moore Ratio on the Morphology and Crystallinity of 3C-SiC/Si(100) by the Modified Two-Step Carbonization Process

A modified two-step carbonization process was used to growth high oriented 3C-SiC films on Si(100) substrates by using SiH4 and C3H8 as precursors. The investigation revealed that the C/Si Moore ratio has important influences on the SiC nucleation model on Si substrates and the crystal quality of 3C-SiC films. The effect of C/Si Moore ratio on the SiC/Si(100) were evaluated by Microscopy and SEM. This indicates that the growth model of the individual nuclei gradually changed from vertical to lateral growth as the C/Si Moore ratio increased. High-resolution X-ray diffraction and Raman spectra were used to analyze the crystalline quality of 3C-SiC films grown at 1385 °C under different C/Si ratios. The results showed that the optimum C/Si Moore ratio for high oriented and high crystal quality 3C-SiC films was 1.6. The mirro-like high-crystallinity 3C-SiC films on the Si(100) was grown with a 1.6 C/Si ratio at 1385 °C for 1hr. The surface roughness was 3.6nm.DOI: http://dx.doi.org/10.5755/j01.ms.23.3.16323

Thermal & chemical analyses of hydrothermally derived carbon materials from corn starch

Hydrothermal and pyrolytic carbonization were used in this study to prepare a range of carbonaceous materials from corn starch powder. The objective of the study was to investigate the relationship between microstructures of the hydrothermally carbonized materials synthesized by a two-step carbonization process and their thermophysical and thermochemical properties. Differences in thermal behavior, as observed by thermogravimetric measurements conducted in air, were investigated by supplementary studies using elemental and proximate analysis, Fourier transform infrared spectrometry (FTIR), X-ray photoelectron spectroscopy (XPS) characterisation and weight loss kinetic modeling. The results indicated that the degree of the aromatization of obtained materials with higher carbon contents could be increased by subsequent annealing at higher temperatures. The resulting materials with different carbon skeletons displayed different kinetic behavior upon heating. Kinetic modeling of the thermogravimetric data revealed a low temperature and a high temperature combustion region with different kinetics parameters, thus demonstrating the potential of hydrothermal carbonization (HTC) as a synthesis strategy for fine-tuned functional high-purity combustion fuel preparation.