Carbon Letters 2021 KCI Impact Factor : 0.52

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2021, Vol.31, No.5

  • 1.

    Characterization of prepared eco-friendly biochar from almond (Terminalia catappa L) leaf for sequestration of bromophenol blue (BPB) from aqueous solution

    Jabar Jamiu Mosebolatan , Owokotomo Ignatius Adekunle , Ayinde Yusuf Timilehin and 3 other persons | 2021, 31(5) | pp.1001~1014 | number of Cited : 0
    Abstract
    Novel eco-friendly adsorbents were prepared through pyrolysis and acid activation of raw almond leaf (RAL) to form almond leaf biochar (ALB) and chemically activated almond leaf biochar (CAL), respectively. The prepared adsorbents were characterized using TGA, FTIR, SEM–EDX, BET and XRD techniques and their physicochemical properties investigated. RAL, ALB and CAL were utilized for adsorption of BPB dye from aqueous solution using batch technique under optimum conditions. The optimum dye adsorbed by RAL, ALB and CAL were 92.83, 93.21 and 94.89%, respectively at pH 3, dye initial conc. (100 mg/L), adsorbent dose (0.04 g/25 mL), 60 min contact time and 301 K adsorption temperature. Although, Langmuir maximum monolayer adsorption capacities were found to be 365.36, 535.62 and 730.46 mg/g for RAL, ALB and CAL, respectively, but isotherm conformed to Freundlich model. Kinetic study confrmed suitability of pseudo-second-order model with rate constant 9.33×10–4, 9.91×10–4 and 12.60×10−4 g mg−1 min−1 for RAL, ALB and CAL, respectively. Negative values of thermodynamic parameters (∆G and ∆H) established sequestration process to be spontaneous and exothermic. RAL, ALB and CAL were discovered to be highly efcient adsorbents that could be used in place of expensive commercial adsorbents.
  • 2.

    Size dependent conduction characteristics of catalyst-multi-walled carbon nanotube junction

    Barnett Chris J. , Orbaek White Alvin , Barron Andrew R. | 2021, 31(5) | pp.1015~1021 | number of Cited : 0
    Abstract
    Multi-walled carbon nanotubes (MWCNTs) grown by chemical vapor deposition retain the residual catalyst particles from which the growth occurred, which are considered a detriment to MWCNTs’ performance, especially electrical conductivity. The frst direct measurements have been made of the electrical transport through the catalyst cap into the MWCNT using nanoscale 2-point-probe to determine the efects of the catalyst particle’s size and the diameter ratio with its associated MWCNT on the electrical transport through the catalyst cap as compared to the inherent conductivity of the MWCNT. The MWCNT diameter is independent of the catalyst size, but the ratio of the catalyst cap diameter to MWCNT diameter (DC/DNT) determines the conduction mechanism. Where DC/DNT is greater than 1 the resulting I–V curve is near ohmic, and the conduction through the catalyst (RC+NT) approaches that of the MWCNT (RNT); however, when the DC/DNT<1 the I–V curves shift to rectifying and RC+NT> >RNT. The experimental results are discussed in relation to current crowding at the interface between catalyst and nanotube due to an increased electric feld.
  • 3.

    The use of semi-coke for phenol removal from aqueous solutions

    Krasnova Tamara A. , Gora Natalia V. , Belyaeva Oxana V. and 3 other persons | 2021, 31(5) | pp.1023~1032 | number of Cited : 0
    Abstract
    The paper deals with a comparative study of equilibrium and kinetics of phenol adsorption from aqueous solutions by means of commercial activated carbons and semi-cokes, difering in the nature of feedstock, production technology and structural characteristics. The main adsorption parameters are calculated with the usage of Langmuir and Dubinin–Radushkevich equations. The change in the characteristics of the structure and state of the surface of semi-coke P2 as a result of modifcation is estimated. It was found that phenol adsorption kinetics is described by a pseudo-second-order model. The adsorption rate constants and the coefcient of external difusion mass transfer are calculated. It is proved that phenol extraction from aqueous solutions presents a mixed-difusion nature, and the process rate is limited by external mass transfer for 13 min for SKD-515 and 22 min for ABG. To increase the adsorption capacity, the oxidative modifcation of the semi-coke P2 was carried out. Considering the economic and technological aspects, ABG semi-coke is recognized as a promising sorbent for phenol extraction from aqueous media.
  • 4.

    Probe on hard carbon electrode derived from orange peel for energy storage application

    Meenatchi T. , Priyanka V. , Subadevi R. and 3 other persons | 2021, 31(5) | pp.1033~1039 | number of Cited : 0
    Abstract
    Activated non-graphitizable hard carbon using orange peel with mesoporous structure has been prepared by pyrolyzation at 700, 800, 900 °C using chemical activation method. The activated orange peel-derived hard carbon has been characterized for its mesoporous and disordered structure. TG-DSC gives the information for the changes about sample composition and thermal stability of the materials. Increasing the carbonization temperature for orange peel precursor using NaOH as activating agent, elevates the pore diameter, which thereby facilitating the insertion of Na+. Raman and X-ray difraction confrms the presence of disordered carbon. The surface morphology of the material was analyzed by scanning eletron microsope and nitrogen (N2) adsorption and desorption analysis give the morphology, mesopore size (3.374, 3.39 and 4 nm) and surace area (60.164, 58.99 and 54.327 m2 /g) of the orange peel-derived hard carbon. Hence, this work strongly evidences that the biomass-derived hard carbon with good porosity and paves way of superior electrochemical performance for emerging sodium ion batteries.
  • 5.

    Capacitive behavior of functionalized activated carbon-based all-solid-state supercapacitor

    Leekyuseok , Seo Ye Ji , Jeong Hyeon Taek | 2021, 31(5) | pp.1041~1049 | number of Cited : 0
    Abstract
    In this report, we incorporate activated carbon (AC) onto aluminum substrate via doctor blade method to produce an all-solid-state supercapacitor. The electrochemical properties of the all-solid-state supercapacitor were characterized by cyclic voltammetry and electrochemical impedance spectroscopy. Galvanostatic charge/discharge tests also were carried out to exhibit stability of the AC-based supercapacitor. The impedance and charge/discharge curves of the all-solid-state supercapacitor showed good capacitive behavior after functionalized AC. The highest specifc capacitance obtained for the AC-based supercapacitor was 106 F g−1. About 160% of specifc capacitance increased after functionalization of the AC, which indicated that modifcation of the AC by nitric acid was able to introduce functional groups on the AC and improve its electrochemical performances.
  • 6.

    Coulomb mechanism of Raman radiation in graphene

    Melkonyan S. V. | 2021, 31(5) | pp.1051~1059 | number of Cited : 0
    Abstract
    The phenomena of single-layer graphene resonant photoluminescence and Raman radiation are discussed taking into account the photo-generated electron–hole Coulomb interaction. On the base of general principles of a many-particle interactions and the interband resonance optical transitions a photon radiation new mechanism (Coulomb mechanism) is proposed. Through Stokes 2D’-mode particular case analysis has shown that the graphene photoluminescence and the resonant Raman radiation are characterized by the same frequency shifts. Probabilities of resonance photo-radiation processes have been presented where the electron–hole Coulomb attraction has been taken into account. The probabilities are the same fourth-order small values. The weak photo-radiation Coulomb mechanism has a common character. It is applicable to both zero and nonzero band gap crystals.
  • 7.

    First-principles calculation of volatile organic compound adsorption on carbon nanotubes: Furan as case of study

    Torres Ana M. , Correa J. D. | 2021, 31(5) | pp.1061~1070 | number of Cited : 0
    Abstract
    Sensing of volatile organic compounds (VOCs) is a growing research topic because of the concern about their hazard for the environment and health. Furan is a VOC produced during food processing, and it has been classifed as a risk molecule for human health and a possible biomarker of prostate cancer. The use of carbon nanotubes for VOCs sensing systems design could be a good alternative. In this work, a theoretical evaluation of the interactions between furan and zigzag single-wall carbon nanotubes takes into account diferent positions and orientations of the furan molecule, within a density-functional theory frst-principles approach. The van der Waals interactions are considered using diferent exchange-correlation functionals (BH,C09, DRSLL and KBM). The results indicate that vdW-functionals do not signifcantly afect geometry; however, the binding energy and the distance between furan and nanotube are strongly dependent on the selected exchange-correlation functional. On the other hand, the efects of single and double vacancies on carbon nanotube are considered. It was found that the redistribution of charge around the single-vacancy afects the bandgap, magnetic moment, and binding energy of the complex, while furan interaction with a double-vacancy does not considerably change the electronic structure of the system. Our results suggest that to induce changes in the electronic properties of carbon nanotubes by furan, it is necessary to change the nanotube surface, for example, by means of structural defects.
  • 8.

    Synthesis and characterization of microporous activated carbon from rubberwood by chemical activation with KOH

    Thongpat Wasutha , Taweekun Juntakan , Maliwan Kittinan | 2021, 31(5) | pp.1079~1088 | number of Cited : 0
    Abstract
    This research aims to study the efect of impregnation ratio and activation temperature on microporous development of activated carbon (AC). Rubberwood chips, which are wasted from home furnishing industry, were used as precursors for synthesized of activated carbon by chemical activation employing Potassium hydroxide (KOH) as activation agent. Rubberwood char was carbonized at 400 °C for 1 h under inert gas. In this experiment, the rubberwood chars were impregnated with KOH solution by 1:1–3 (char: KOH) impregnation ratio for 24 h, then the samples were activation at 600–800 °C. Surface area, pore volume, micropore volume, pore size distribution, adsorption isotherm and porous structure were analyzed in this experiment to identify the properties of derived activated carbon. According to the investigation, the activated carbon, activated at 800 °C with impregnation ratio of 1:3, demonstrated the highest surface area, pore volume and micropore volume as 1491.75 m2 /g, 0.6777 cm3 /g, and 0.5813 cm3 /g, respectively. Its average pore size was 1.82 nm and it also showed type I adsorption isotherm which indicates as microporous solid.
  • 9.

    Comparison of ultrasonic-treated rice husk carbon with the conventional carbon black towards improved mechanical properties of their EPDM composites

    Kim In Tae , Lee Kwang Ho , SINHA TRIDIB KUMAR and 1 other persons | 2021, 31(5) | pp.1071~1077 | number of Cited : 0
    Abstract
    Because of depletion of fossil fuel from the earth curst and increase of environmental concerns, in search of an efcient alternative to the traditional carbon black (CB), a biochar known as rice husk carbon (RHC) has been examined here as a fller material to develop the EPDM composite. In this regard, the ball milled RHC was further treated with ultrasonic wave and used with or without its surface treatment by the silane coupling agent [i.e., 3-mercaptopropyl triethoxysilane (3-MPTMS)]. Among the RHC, ultrasonic treated RHC (UHC) and silane treated UHC (USHC), the EPDM composite of USHC showed nearly similar tensile strength to that of the CB (e.g., CB: 33.88 kgf/cm2 , USHC: 31.38 kgf/cm2 at 20 wt% fller loading) with an enhanced elongation at break (e.g., CB: 206%, USHC: 342% at 20 wt% fller loading) and surprisingly much less compression set value (CB: 40.87%, USHC: 18.95% even after 40 wt% of fller loading). Compared to RHC, the UHC also showed its better performance next to the USHC. In addition to presence of both the carbon and silica in RHC and additional silica within the fexible aliphatic chain in USHC, the disintegration of RHC by ultrasonic treatment towards its narrow particle distribution, smaller particle size, and increased surface area is considered very much efective to develop the corresponding high performance EPDM composites. Thus, the use of waste material, i.e., rice husk through the ultrasonication of RHC followed by its surface treatment can be used as a potential fller material to prepare the environment friendly and cost efective high performing composites to be used in diferent efcient end products, and motivated further for industrial upscaling.
  • 10.

    Hydrogenation effects on the thermal and magnetic properties of mono- and bilayer graphene

    Sohrabi Sani Shahdokht , Mousavi Hamze , Jalilvand Samira and 1 other persons | 2021, 31(5) | pp.1089~1096 | number of Cited : 0
    Abstract
    In the present study, the nearest-neighbor tight-binding model has been employed to calculate the density of states (DOS), electronic heat capacity (EHC), and Pauli magnetic susceptibility (PMS) of hydrogenated systems, namely monolayer graphone and graphane, bilayer graphone–graphene, and bilayer graphane–graphene. Then, the results have been compared with that of monolayer and simple bilayer graphene. It was found that the behaviors of hydrogenated systems difer from those of monolayer and bilayer graphene near the Fermi Level. Also, monolayer graphone and bilayer graphone–graphene exhibit a high peak near the Fermi level. Graphane monolayer, on the other hand, has no states around the Fermi level. Furthermore, bilayer graphane–graphone, similar to graphene, is a semimetal. Also, Schottky anomaly peaks in the EHC curves and crossovers in the PMS curves can be observed, which have divided the domain into two regions of low and high temperature. Compared to hydrogenated systems, the Schottky anomaly in graphene monolayer and bilayer graphene occurred at lower temperatures, while the PMS of monolayer graphone and bilayer graphone–graphene were faster than other systems in reaching the crossover. From the theoretical standpoint, these phenomena are due to the proportional relation of the PMS and EHC with the DOS.
  • 11.

    Synthesis and characterization activated carbon using a mix (asphalt-polypropylene waste) for novel azo dye (HNDA) adsorption

    Toohi Homam T. S. AL-Sayd , Rabeea Muwafaq Ayesh , Abdullah Jasim Ali and 1 other persons | 2021, 31(5) | pp.837~849 | number of Cited : 0
    Abstract
    This work reveals a modifed method for the preparation of activated carbon (P-ACA) using low-cost materials (mix natural asphalt: polypropylene waste). The P-ACA was prepared at 600 °C by assisting KOH and HF. The morphological variations and chemical species of the P-ACA were characterized using SEM–EDX and FTIR. The active surface area, density and ash content of the P-ACA were also investigated. Adsorption properties of P-ACA were used for the thermodynamic and kinetic study of 4-((2-hydroxy naphthalenyl) diazenyl) antipyrine (HNDA), which was prepared as a novel azo dye in this work. The optimal conditions (initial concentration, adsorbent dose, contact time and temperature) of the adsorption process were determined. Adsorption isotherms (Freundlich and Langmuir) were applied to the experimental data. These isothermal constants were used to describe the nature of the adsorption system, and the type of interaction between the dye and the P-ACA surface. The results have indicated that the mixture (Natural asphalt-polypropylene waste) is efcient for the synthesis of P-ACA. The synthesized P-ACA demonstrates the presence of pores on the surface with various diameter ranges (from 1.4 to 4.5 μm). Furthermore, P-ACA exhibits an active surface area of 1230 m2 g−1, and shows a high adsorption capacity for HNDA.
  • 12.

    Activated carbon@MgO@Fe3O4 as an efficient adsorbent for As (III) removal

    Esmaeili Hossein , Mousavi Seyyed Mojtaba , Hashemi Seyyed Alireza and 2 other persons | 2021, 31(5) | pp.851~862 | number of Cited : 0
    Abstract
    In this study, Fe3O4/MgO/Activated carbon composite was used to remove arsenic ion (As (III)) from aqueous media. To this end, Frangula Alnus was used to prepare activated carbon (AC) by calcination in the furnace at 700 °C for 4 h and was then used to synthesize the MgO/Fe3O4/AC composite. To study the surface properties of the composite, various analyses such as SEM, EDX/Mapping, FTIR, DLS, BET and VSM were applied. According to the BET analysis, the specifc surface area and average pore size of the Fe3O4/MgO/AC composite were obtained as 190.92 m2 /g and 7.57 nm, respectively, which showed that the aforementioned nanocomposite had a mesoporos structure with an excellent specifc surface area. Also, VSM analysis indicated that the composite had a superparamagnetic property and could be easily separated from the solution by a magnet. Moreover, the results of the As (III) sorption indicated that the highest uptake efciency was obtained 96.65% at pH=7, adsorbent dosage=0.13 g/L, t=35 min, T=45 °C and Co=6 mg/L. In addition, the pseudo-second-order model could better describe the kinetic behavior of the sorption process. Furthermore, Langmuir model was the best model to describe the equilibroium behavior of the As(III) ion sorption. Besides, according to the the thermodynamic study, enthalpy change and entropy change were obtained 58.11 kJ/mol and 224.49 J/mol.K, respectively, indicating that the sorption process was spontaneous and endothermic. According to the results, the Fe3O4/MgO/AC composite was a good adsorbent with the extraordinary properties, which can be used on an industrial scale.
  • 13.

    DFT and experimental study on adsorption of dyes on activated carbon prepared from apple leaves

    Abdel-Aziz Mohamed Helmy , El-Ashtoukhy Elsayed Zakaria , Bassyouni Mohamed and 4 other persons | 2021, 31(5) | pp.863~878 | number of Cited : 0
    Abstract
    This work reports utilization of apple leaves as a source of activated carbon. Activated carbon from apple leaves is prepared by two diferent methods, thermal activation where AC1 is obtained and chemical activation using H3PO4 and ZnCl2 where AC2 and AC3 are obtained, respectively. XRD analysis revealed that all types of prepared ACs have a semi-crystalline nature with a mean crystallite size of 13, 21.02, and 39.47 nm for AC1, AC2, and AC3, respectively. To identify the most suitable desorption temperature, the exothermic behavior was discovered for the three types of ACs by DSC. The exothermic onset temperatures are 340 °C, 200 °C, 400 °C, or AC1, AC2, and AC3, respectively. The point of zero charge for the three types of ACs is 8.6, 7.3, and 2.5 for AC1, AC2, and AC3, respectively. The BET surface area analysis data demonstrated that mesoporous structure was developed in AC1 and AC2, while a microporous structure was developed in AC3. Quantum chemical calculations for ACs is carried out using Density Functional Theory (DFT). Application of the prepared ACs in adsorption of basic dye C.I. base blue 47 is studied. The maximum removal efciency was 65.1%, 96% and 99% for AC1, AC2, and AC3, respectively under the infuence of diferent operating aspects. Adsorption data are modeled by Langmuir, Freundlich, and Temkin isotherms. The data revealed that adsorption of basic dye C.I. base blue 47 on AC1 follows Langmuir isotherm and adsorption on AC2 and AC3 follows Freundlich isotherm.
  • 14.

    Triazine-based 2D covalent organic framework-derived nitrogen-doped porous carbon for supercapacitor electrode

    Vargheese Stella , Dinesh Muthu , Kavya K. V. and 3 other persons | 2021, 31(5) | pp.879~886 | number of Cited : 0
    Abstract
    Doped porous carbon materials have attracted great interest owing to their excellent electrochemical performance toward energy storage applications. In this report, we described the synthesis of nitrogen-doped porous carbon (N-PC) via carbonization of a triazine-based covalent organic framework (COF) synthesized by Friedel–Crafts reaction. The as-synthesized COF and N-PC were confrmed by X-ray difraction. The N-PC exhibited many merits including high surface area (711 m2 g−1), porosity, uniform pore size, and surface wettability due to the heteroatom-containing lone pair of electron. The N-PC showed a high specifc capacitance of 112 F g−1 at a current density of 1.0 A g−1 and excellent cyclic stability with 10.6% capacitance loss after 5000 cycles at a current density of 2.0 A g−1. These results revealed that the COF materials are desirable for future research on energy storage devices.
  • 15.

    Production of B-doped reduced graphene oxide using wet-process in tetrahydrofuran

    Shin yunseok , PARK SUNGJIN | 2021, 31(5) | pp.887~893 | number of Cited : 1
    Abstract
    Graphene-based materials show excellent properties in various applications because of their electrical properties, large surface areas, and high tolerance for chemical modifcation. The use of wet-process is a promising way for their mass production. Heteroatom doping is one of the common methods to improve their electrical, physical, and electrochemical properties. In this work, we develop a new route for the production B-doped graphene-based materials using low-temperature wet-process, which is the reaction between graphene oxide suspensions and a BH3 adduct in tetrahydrofuran under refux. Elemental mapping images show well-dispersed B atoms along the materials. Various spectroscopic characterizations confrm the reduction of the graphene oxide and incorporation of B atoms into the carbon network as high as ~2 at%. The materials showed electrocatalytic activity for oxygen reduction reactions.
  • 16.

    Nonlinear buckling analysis of double-layered graphene nanoribbons based on molecular mechanics

    Namnabat Mohammad Sadegh , Barzegar Amin , Barchiesi Emilio and 1 other persons | 2021, 31(5) | pp.895~910 | number of Cited : 1
    Abstract
    Double-layer graphene nanoribbons promise potential application in nanoelectromechanical systems and optoelectronic devices, and knowledge about mechanical stability is a crucial parameter to fourish the application of these materials at the next generation of nanodevices. In this paper, molecular mechanics is utilized to investigate nonlinear buckling behavior, critical buckling stress, and lateral defection of double-layered graphene nanoribbons under various confgurations of stacking mode and chirality. The implicit arc-length iterative method (modifed Riks method) with Ramm’s algorithm is utilized to analyze the nonlinear structural stability problem. The covalent bonds are modeled using three-dimensional beam elements in which elastic moduli are calculated based on molecular structural mechanics technique, and the interlayer van der Waals (vdW) interactions are modeled with nonlinear truss elements. An analytical expression for Young’s modulus of nonlinear truss elements is derived based on the Lennard–Jones potential function and implemented in numerical simulation with a UMAT subroutine based on FORTRAN code to capture the nonlinearity of the vdW interactions during the buckling analysis. The results indicate that the highest critical buckling stress and the minimum lateral defection occur for armchair and zigzag chirality, both with AB stacking mode, respectively. Moreover, the critical buckling stress is found to be directly dependent on the mode shape number regardless of in-phase or anti-phase defection direction of layers. Lateral defection exhibits a similar trend with mode shape in anti-phase mode; however, it is decreasing by increasing mode shape number in in-phase mode.
  • 17.

    Effect of crystallinity and particle size on coke-based anode for lithium ion batteries

    Lee Seung Eun , Kim Ji Hong , Lee, Young-Seak and 2 other persons | 2021, 31(5) | pp.911~920 | number of Cited : 0
    Abstract
    This study examined the efects of micro- (crystallinity) and macro (orientation)-crystalline properties of graphite on the initial efciency, discharge capacity, and rate performance of anodic materials. Needle coke and regular coke were selected as raw materials and pulverized to 2–25 μm to determine the efects of crystalline properties on particle shape after pulverization. Needle coke with outstanding crystallinity had high initial efciency, and smaller particles with larger specifc surface areas saw increased irreversible capacity due to the formation of SEI layers. Because of cavities existing between crystals, the poorer the crystalline properties were, the greater the capacity of the lithium ions increased. As such, regular coke had a 30 mAh/g higher discharge capacity than that of needle coke. Rate performance was more afected by particle size than by crystalline structure, and was the highest at a particle distribution of 10–15 μm.
  • 18.

    Effects of pressurized PFO-based pitch coking conditions on coke yield and graphite conductivity

    Cho Jong Hoon , Bai Byong Chol | 2021, 31(5) | pp.921~927 | number of Cited : 0
    Abstract
    In the present study, pyrolyzed fuel oil (PFO)-based pitch without impurities was used to prepare coke under pressure, and the preparation yield and the powder resistance depending on the graphitization were investigated. The preparation yield of green coke by pressurized coking at 500 °C was about 26–27% higher than that at normal pressure. However, the coke yield after the thermal treatment of green coke at 900 °C was lower by 10.6–14.8% at the pressurization conditions than under normal pressure. This may be because the substances that are not vaporized under the pressurized conditions remain in the reactants and then are discharged later. The coke yield after the thermal treatment at 900 °C was higher by 14.9–28.3% under the pressurized conditions than under the normal pressure, indicating that the low-boiling point materials of the pitch participated more in coke polymerization under the pressurized conditions. The density of the coke prepared under the pressurized conditions was lower than that of the coke prepared under normal pressure, because the low-boiling point materials of the pitch participated in the reaction. However, after graphitization, the density values became similar (2.27–2.26 g/cm3 ). The volume resistivity of the graphitized samples was in a range of 0.499×10–2–0.384×10–2 Ω cm, indicating that the coke samples have similar electrical properties. The results of the present study show that, in comparison with the conventional normal-pressure process, the pressurized coking process can improve the yield through the participation of low-boiling point materials in the polymerization reaction, while maintaining the properties of the prepared coke and graphite, such as the conductivity and density.
  • 19.

    Evaluation of the sp3/sp2 ratio of DLC films by RF-PECVD and its quantitative relationship with optical band gap

    Sheng Hongxun , Xiong Wenwen , Zheng Songsheng and 3 other persons | 2021, 31(5) | pp.929~939 | number of Cited : 0
    Abstract
    DLC has been attractive as semiconductor materials for solar cell due to its biological friendliness, fexible microstructures, and especially its tunable band gap. In order to fabricate high-efciency multiband gap solar cell, it is important to control the sp3 / sp2 bonds ratio of DLC flm corresponding to optical band gap (Eg). There are many references reporting the relations among the fabrication conditions, Eg, sp3 /sp2 , and ID/IG. However, a more comprehensive database is needed for controllable fabrication. Especially, the quantitative relationship of sp3 /sp2 ratio to Eg of DLC flm by PECVD is unclear. In this paper, 36 sets of DLC flms were fabricated by RF-PECVD. Characterization methods of XPS, Raman spectroscopy, and IR absorption have been used to determine the sp3 /sp2 ratio of DLC flms. UV/visible light absorption method has applied to evaluate Eg. The Eg obtained is in the range 1.45–3.0 eV. Our results agree well with the references. The XPS spectra gives a linear relationship as Eg=− 0.161 (±0.136)+26.095 (±1.704) · {sp3 (XPS)/sp2 }, the Raman spectra shows a linear function that Eg=1.327 (±0.046)+0.428 (±0.036) · (ID/IG), as well as the FTIR analysis demonstrates that Eg=− 0.492 (±0.093)+0.464 (±0.044) · {sp3 (FTIR)/sp2 }.
  • 20.

    Preparation and characterization of chars and activated carbons from wood wastes

    Yan Qiangu , Li Jinghao , Cai Zhiyong | 2021, 31(5) | pp.941~956 | number of Cited : 1
    Abstract
    Preparation of activated carbons from wood waste including northern hardwood pins-fnes and wood dust was conducted and then compared through the following methods: physical pyrolysis and CO2 activation, vacuum pyrolysis and CO2 activation, CO2 gasifcation, and vacuum CO2 gasifcation processes. Experimental results show that chars and activated carbons with high surface area and pore volume are produced from wood waste through a vacuum CO2 pyrolysis/gasifcation process. The efects of operation variables of vacuum pyrolysis/gasifcation on the properties of chars and activated carbons were investigated to identify and optimize the temperature, heating time, and heating rate. The optimized vacuum CO2 gasifcation conditions were found to be a temperature of 800 °C, a heating rate of 20 °C/min, and a holding time of 2 h respectively. The prepared wood-chars and activated carbons were characterized by nitrogen physisorption, scanning electron microscopy (SEM). Fourier transform infrared (FTIR) spectra determined any changes in the surface functional groups produced during diferent preparation stages.
  • 21.

    Production of activated carbon derived from agricultural by-products via microwave-induced chemical activation: a review

    Ahmad Abdulbari A. , Al-Raggad Marwan , Shareef Noama | 2021, 31(5) | pp.957~971 | number of Cited : 0
    Abstract
    Biomass of agricultural waste is getting increasing attention all over the world as it is a kind of renewable, abundantly available, low cost, and environmentally friendly resource. Preparation of activated carbon from agricultural waste via microwave-assisted chemical agent activation. The porosity, surface area, and functional and surface chemistry were featured by means of low-temperature nitrogen adsorption, Scanning Electron Microscopy, (SEM) and Fourier Transform Infrared Spectroscopy (FTIR). The best conditions resulted in activated carbon with adsorption capacity of 517.5 mg/g and carbon yield of 80.99%. The activated carbons from carbonized tobacco stem with K2CO3 activation by microwave radiation is highest of surface area, and total pore volume corresponded to 2557 m2 /g, and 1.647 cm3 /g, respectively, with a high contribution of mesopores, microwave power of 700 W, and irradiation time of 30 min. The results of the review showed that chemical activation could develop both microporosity and mesoporosity. The fndings support the potential to prepare high surface area and micropore-activated carbon from agricultural waste by microwave-induced chemical activation.
  • 22.

    Activated carbons effectively purified by post-heat treatment under vacuum conditions

    kimjunam , T. Nguyen Hoai Van , Bahk Gyung Jin and 2 other persons | 2021, 31(5) | pp.973~984 | number of Cited : 0
    Abstract
    The efect of heat treatment and vacuum conditions on the textural properties and electrochemical performance of commercially available activated carbons (ACs) was investigated. The AC after post-heat treatment was characterized by nitrogen adsorption–desorption, X-ray difraction, Raman spectroscopy, X-ray photoelectron spectroscopy, and Fourier-transform infrared spectroscopy measurements. The ACs treated under vacuum conditions exhibit a higher specifc surface area and micropore surface area than those treated under nitrogen atmospheric pressure without signifcantly afecting the graphite structure of the AC. Under 800 °C temperature and vacuum conditions (AC-V800), the AC with the highest Brunauer– Emmett–Teller surface area of 1951.9 m2 g−1 (16.4% improvement relative to that of the original AC (1677.2 m2 g−1)) was obtained. This is attributed to the removal of oxygen-containing functional groups and volatile matters in the carbon by thermal treatment under vacuum conditions. Consequently, the electric double-layer capacitor using ACs treated under vacuum conditions (1 kPa) at 800 °C (AC-V800) shows considerably improved electrochemical performance in terms of higher specifc capacitance and better cycling stability at a high working voltage (3.1 V), compared to the nitrogen-treated and commercial ACs.
  • 23.

    A criterion combined of bulk and surface lithium storage to predict the capacity of porous carbon lithium-ion battery anodes: lithium-ion battery anode capacity prediction

    Shaker Majid , Ghazvini Ali Asghar Sadeghi , Qureshi Faisal Raza and 1 other persons | 2021, 31(5) | pp.985~990 | number of Cited : 0
    Abstract
    The high level of lithium storage in synthetic porous carbons has necessitated the development of accurate models for estimating the specifc capacity of carbon-based lithium-ion battery (LIB) anodes. To date, various models have been developed to estimate the storage capacity of lithium in carbonaceous materials. However, these models are complex and do not take into account the efect of porosity in their estimations. In this paper, a novel model is proposed to predict the specifc capacity of porous carbon LIB anodes. For this purpose, a new factor is introduced, which is called normalized surface area. Considering this factor, the contribution of surface lithium storage can be added to the lithium stored in the bulk to have a better prediction. The novel model proposed in this study is able to estimate the lithium storage capacity of LIB anodes based on the porosity of porous carbons for the frst time. Benefting porosity value (specifc surface area) makes the predictions quick, facile, and sensible for the scientists and experts designing LIBs using porous carbon anodes. The predicted capacities were compared with that of the literature reported by experimental works. The remarkable consistency of the measured and predicted capacities of the LIB anodes also confrms the validity of the approach and its reliability for further predictions.
  • 24.

    Waste plastic for increasing softening point of pitch and specific surface area of activated carbon based on the petroleum residue

    Kwak Cheol Hwan , Seo Sang Wan , Kim Min Il and 2 other persons | 2021, 31(5) | pp.991~1000 | number of Cited : 0
    Abstract
    Pyrolysis fuel oil (PFO) is used for the manufacturing of high-purity pitch for carbon precursor due to its high carbon content, high aromaticity, and low heterogeneous element and impurity content. Pitch is commonly classifed with its softening point, which is most considerable physical property afecting to various characteristics of the carbon materials based on pitch, such as electrical and thermal conductivity, mechanical strength, and pore property. Hence, the softening point should be controlled to apply pitch to produce various carbon materials for diferent applications. Previous studies introduce reforming process under high pressure and two step heat treatment for the synthesis of pitch with high softening point from PFO. These methods lead to a high process cost; therefore, it is necessary to develop a process to synthesize the pitch with high softening point by using energy efective process at a low temperature. In this study, waste polyethylene terephthalate (PET) was added to control the softening point of PFO-based pitch. The pitch synthesized by the heat treatment with the addition of PET showed the softening point higher than that of the pitch synthesized with only PFO. The softening point of PFObased pitch synthesized at 420 °C was 138.3 °C, while that of the pitch synthesized by adding PET under the same process conditions was 342.8 °C. It is proposed that the efect of the PET addition on the increase in the softening point was due to the radicals generated from thermal degradation of PET. The radicals from PET react with the PFO molecules to promote the polymerization and fnally increase the molecular weight and softening point of the pitch. In addition, activated carbon was prepared by using the pitch synthesized by adding PET, and the results showed that the specifc surface area of the activated carbon increased by the addition of PET. It is expected that the pitch synthesis method with PET addition signifcantly contributes to the manufacture of pitch and activated carbon.