C | June 2023 - Browse Articles

18 pages, 2619 KiB

Open AccessArticle

Carbon Nanotubes as Biosensors for Releasing Conjugated Bisphosphonates–Metal Ions in Bone Tissue: Targeted Drug Delivery through the DFT Method

by Fatemeh Mollaamin and Majid Monajjemi

C 2023, 9(2), 61; https://doi.org/10.3390/c9020061 - 19 Jun 2023

Cited by 3 | Viewed by 1425

Abstract

Bisphosphonate (BP) agents have attracted much attention for their precise therapy in some skeletal maladies demonstrated by enhancing osteoclast-mediated bone resorption. In this work, the use of CAM-B3LYP/6-311+G(d,p)/LANL2DZ to estimate the susceptibility of single-walled carbon nanotube (SWCNT) for adsorbing alendronate, ibandronate, neridronate, and [...] Read more.

Bisphosphonate (BP) agents have attracted much attention for their precise therapy in some skeletal maladies demonstrated by enhancing osteoclast-mediated bone resorption. In this work, the use of CAM-B3LYP/6-311+G(d,p)/LANL2DZ to estimate the susceptibility of single-walled carbon nanotube (SWCNT) for adsorbing alendronate, ibandronate, neridronate, and pamidronate chelated to two metal cations of 2Mg²⁺, 2Ca²⁺, and 2Sr²⁺ through nuclear magnetic resonance and thermodynamic parameters has been accomplished. For most biological medications, oral bioavailability is too low to reach a therapeutic level, and advanced delivery systems such as formulations including permeation enhancers or enzyme inhibitors, lipid-based nanocarriers, and microneedles will likely increase the oral bioavailability of these medications properly. Therefore, the measurements have described that the eventuality of using SWCNT and BP agents becomes the norm in metal chelating of the drug delivery system, which has been selected through (alendronate, ibandronate, neridronate, pamidronate) → 2X (X = Mg²⁺/Ca²⁺/Sr²⁺) complexes. The NMR results of chelated alendronate, ibandronate, neridronate, and pamidronate complexes adsorbed onto (5,5) armchair SWCNT have remarked the location of active sites of tagged nitrogen (N), phosphorus (S), oxygen (O), and metal cations of magnesium (Mg²⁺), calcium (Ca²⁺), and strontium (Sr²⁺) in these molecules which replace the movement of the charge electron transfer in polar bisphosphonates (BPs) toward (5,5) armchair carbon nanotube (CNT). The thermodynamic results have exhibited that the substitution of 2Ca²⁺ cation by 2Sr²⁺ cation in the compound of the bioactive glasses can be efficient for treating vertebral complex fractures. However, the most fluctuation in the Gibbs free energy for BPs → 2Sr²⁺ has been observed at 300 K. This manuscript aimed to show that (5,5) armchair SWCNT can easily penetrate in the bone cells, delivering chelated BP–cations directly to the bone tissue. Drug delivery systems can improve the pharmacological profile, therapeutic profile, and efficacy of BP drugs and lower the occurrence of off-targets. Full article

(This article belongs to the Special Issue Carbon Nanohybrids for Biomedical Applications)

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17 pages, 3888 KiB

Open AccessArticle

Phosphorus/Sulfur-Enriched Reduced Graphene Oxide Papers Obtained from Recycled Graphite: Solid-State NMR Characterization and Electrochemical Performance for Energy Storage

by Mariana A. Vieira, Tainara L. G. Costa, Gustavo R. Gonçalves, Daniel F. Cipriano, Miguel A. Schettino, Jr., Elen L. da Silva, Andrés Cuña and Jair C. C. Freitas

C 2023, 9(2), 60; https://doi.org/10.3390/c9020060 - 12 Jun 2023

Viewed by 1556

Abstract

The reduction of graphene oxide (GO) by means of thermal and/or chemical treatments leads to the production of reduced graphene oxide (rGO)—a material with improved electrical conductivity and considered a viable and low-cost alternative to pure graphene in several applications, including the production [...] Read more.

The reduction of graphene oxide (GO) by means of thermal and/or chemical treatments leads to the production of reduced graphene oxide (rGO)—a material with improved electrical conductivity and considered a viable and low-cost alternative to pure graphene in several applications, including the production of supercapacitor electrodes. In the present work, GO was prepared by the oxidation of graphite recycled from spent Li-ion batteries using mixtures of sulfuric and phosphoric acids (with different H₂SO₄/H₃PO₄ ratios), leading to the production of materials with significant S and P contents. These materials were then thermally reduced, resulting in rGO papers that were investigated by solid-state ¹³C and ³¹P nuclear magnetic resonance, along with other methods. The electrochemical properties of the produced rGO papers were evaluated, including the recording of cyclic voltammetry and galvanostatic charge–discharge curves, besides electrochemical impedance spectroscopy analyses. The samples obtained by thermal reduction at 150 °C exhibited good rate capability at high current density and high capacitance retention after a large number of charge–discharge cycles. The results evidenced a strong relationship between the electrochemical properties of the produced materials and their chemical and structural features, especially for the samples containing both S and P elements. The methods described in this work represent, then, a facile and low-cost alternative for the production of rGO papers using graphite recycled from spent batteries, with promising applications as supercapacitor electrodes. Full article

(This article belongs to the Special Issue Carbon and Related Composites for Sensors and Energy Storage: Synthesis, Properties, and Application)

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16 pages, 5276 KiB

Open AccessArticle

Sustainable Supercapacitors Based on Polypyrrole-Doped Activated Biochar from Wood Waste Electrodes

by Ravi Moreno Araujo Pinheiro Lima, Glaydson Simões dos Reis, Ulla Lassi, Eder Claudio Lima, Guilherme Luiz Dotto and Helinando Pequeno de Oliveira

C 2023, 9(2), 59; https://doi.org/10.3390/c9020059 - 05 Jun 2023

Cited by 5 | Viewed by 1865

Abstract

The synthesis of high-performance carbon-based materials from biomass residues for electrodes has been considered a challenge to achieve in supercapacitor-based production. In this work, activated biochar has been prepared as the active electrode material for supercapacitors (SCs), and an effective method has been [...] Read more.

The synthesis of high-performance carbon-based materials from biomass residues for electrodes has been considered a challenge to achieve in supercapacitor-based production. In this work, activated biochar has been prepared as the active electrode material for supercapacitors (SCs), and an effective method has been explored to boost its capacitive performance by employing polypyrrole (PPy) as a biochar dopant. The results for physicochemical characterization data have demonstrated that PPy doping affects the biochar morphology, specific surface area, pore structure, and incorporation of surface functionalities on modified biochar. Biochar-PPy exhibited a surface area of 87 m² g⁻¹, while pristine biochar exhibited 1052 m² g⁻¹. The SCs were assembled employing two electrodes sandwiched with PVA solid-state film electrolyte as a separator. The device was characterized by standard electrochemical assays that indicated an improvement of 34% in areal capacitance. The wood electrodes delivered high areal capacitances of 282 and 370 mF cm⁻² at 5 mA cm⁻², for pure biochar and biochar doped with PPy, respectively, with typical retention in the capacitive response of 72% at the end of 1000 cycles of operation of the supercapacitor at high current density, indicating that biochar-PPy-based electrode devices exhibited a higher energy density when compared to pure biochar devices. Full article

(This article belongs to the Special Issue Nanoporous Carbons for Hydrogen Sorption and Electrochemical Energy Storage)

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11 pages, 2289 KiB

Open AccessArticle

Permafrost Effect on the Spatial Distribution of CO₂ Emission in the North of Western Siberia (Russia)

by Olga Goncharova, Georgy Matyshak, Maria Timofeeva, Stanislav Chuvanov, Matvey Tarkhov and Anna Isaeva

C 2023, 9(2), 58; https://doi.org/10.3390/c9020058 - 01 Jun 2023

Cited by 2 | Viewed by 1370

Abstract

The landscapes in the discontinuous permafrost area of Western Siberia are unique objects for assessing the direct and indirect impact of permafrost on greenhouse gas fluxes. The aim of this study was to identify the influence of permafrost on the CO₂ emission [...] Read more.

The landscapes in the discontinuous permafrost area of Western Siberia are unique objects for assessing the direct and indirect impact of permafrost on greenhouse gas fluxes. The aim of this study was to identify the influence of permafrost on the CO₂ emission at the landscape and local levels. The CO₂ emission from the soil surface with the removed vegetation cover was measured by the closed chamber method, with simultaneous measurements of topsoil temperature and moisture and thawing depth in forest, palsa, and bog ecosystems in August 2022. The CO₂ emissions from the soils of the forest ecosystems averaged 485 mg CO₂ m⁻² h⁻¹ and was 3–3.5 times higher than those from the peat soils of the palsa mound and adjacent bog (on average, 150 mg CO₂ m⁻² h⁻¹). The high CO₂ emission in the forest was due to the mild soil temperature regime, high root biomass, and good water–air permeability of soils in the absence of permafrost. A considerable warming of bog soils, and the redistribution of CO₂ between the elevated palsa and the bog depression with water flows above the permafrost table, equalized the values of CO₂ emissions from the palsa and bog soils. Soil moisture was a significant factor of the spatial variability in the CO₂ emission at all levels. The temperature affected the CO₂ emission only at the sites with a shallow thawing depth. Full article

(This article belongs to the Special Issue Permafrost and Carbon Dioxide Emission)

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16 pages, 7962 KiB

Open AccessArticle

From Waste to Resource: Utilizing Sweet Chestnut Waste to Produce Hydrothermal Carbon for Water Decontamination

by Silvia Izquierdo, Nazaret Pacheco, Carlos J. Durán-Valle and Ignacio M. López-Coca

C 2023, 9(2), 57; https://doi.org/10.3390/c9020057 - 01 Jun 2023

Viewed by 1290

Abstract

Carbonaceous materials are a highly appealing class of adsorbents, owing to their exceptional properties, such as high surface area and thermal and chemical stability. These materials have found successful applications in water purification. Sweet chestnut (Castanea sativa) cupules are disposed of [...] Read more.

Carbonaceous materials are a highly appealing class of adsorbents, owing to their exceptional properties, such as high surface area and thermal and chemical stability. These materials have found successful applications in water purification. Sweet chestnut (Castanea sativa) cupules are disposed of as waste. Valorization of these residues is a step forward in terms of circular economy and sustainability. Meanwhile, per- and poly-fluoroalkyl substances (PFASs) pose significant concerns due to their persistence, bioaccumulation, and toxicity, emerging as contaminants of concern for human health and the environment. This study focuses on preparing carbonaceous material by hydrothermal carbonization from chestnut cupules, followed by their use as adsorbents for PFAS removal from polluted water. The cupule waste material was crushed, ground, sieved, and subjected to hydrothermal treatment at temperatures ranging from 180–200 °C to produce hydrothermal carbons. The adsorbents obtained were characterized by various techniques such as nitrogen adsorption isotherm, porosimetry, point of zero charge, Fourier-transform infrared, scanning electron microscopy, and thermal, elemental, and energy dispersive X-ray analyses. Surface area (S_BET) values of 42.3–53.2 m²·g⁻¹ were obtained; pH_PZC ranged from 3.8 to 4.8. This study also determined the adsorption kinetics and isotherms for removing perfluorooctanoate-contaminated water. The equilibrium was established at 72 h and q_e = 1029.47 mg·g⁻¹. To summarize, this research successfully valorized a biomass residue by transforming it into hydrothermal carbon, which was then utilized as an adsorbent for water decontamination. Full article

(This article belongs to the Special Issue Biomass—a Renewable Resource for Carbon Materials (2nd Edition))

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11 pages, 19286 KiB

Open AccessArticle

Synthetic Pitch from Solvent Extraction of Coal as a Source for High-Quality Graphite

by Akshay Gharpure, Randy L. Vander Wal and Sarma Pisupati

C 2023, 9(2), 56; https://doi.org/10.3390/c9020056 - 01 Jun 2023

Cited by 5 | Viewed by 1499

Abstract

This work evaluates the potential for obtaining graphitizable precursors from domestically available coal as a possible solution to the declining availability of high-quality precursors and projected rapid growth driven by demand for synthetic graphite in the US. The graphitizability of a coal-derived synthetic [...] Read more.

This work evaluates the potential for obtaining graphitizable precursors from domestically available coal as a possible solution to the declining availability of high-quality precursors and projected rapid growth driven by demand for synthetic graphite in the US. The graphitizability of a coal-derived synthetic pitch (Synpitch) obtained by a novel solvent extraction process is compared with a commercially available petroleum pitch. The process outlined in this paper offers the advantages of lower temperature, pressure, and hydrogen addition requirement. An upgraded (higher H/C) aromatic pitch with low quinoline insoluble (QI) and ash content is obtained. The distinctions between the pitches have been characterized using Fourier transform infrared spectroscopy, nuclear magnetic resonance, and thermogravimetric analysis/differential scanning calorimetry. The pitches have been graphitized at 2500 °C and characterized by X-ray diffraction and transmission electron microscopy for graphitic quality assessment. The Synpitch showed larger crystallites (by over 50%) and markedly better nanostructure compared to the commercial pitch used in this study. The structural differences between the pitches are highlighted here to explain the significantly better graphitic quality of the Synpitch. Full article

(This article belongs to the Special Issue Characterization of Disorder in Carbons (2nd Edition))

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18 pages, 3263 KiB

Open AccessArticle

IR Spectroscopy of Vacancy Clusters (Amber Centers) in CVD Diamonds Nanostructured by Fast Neutron Irradiation

by Andrey A. Khomich, Roman Khmelnitskii, Maria Kozlova, Alexander V. Khomich and Victor Ralchenko

C 2023, 9(2), 55; https://doi.org/10.3390/c9020055 - 27 May 2023

Viewed by 1969

Abstract

We investigated the IR absorption spectra of CVD diamond damaged by fast neutrons (>0.1 MeV) with high fluences ranging from 1 × 10¹⁸ to 2 × 10¹⁹ cm⁻² and annealed at temperatures of 200 °C to 1680 °C. After annealing [...] Read more.

We investigated the IR absorption spectra of CVD diamond damaged by fast neutrons (>0.1 MeV) with high fluences ranging from 1 × 10¹⁸ to 2 × 10¹⁹ cm⁻² and annealed at temperatures of 200 °C to 1680 °C. After annealing above 1000 °C, the formation of “amber-centers” (ACs), associated with multivacancy clusters, is detected as deduced from the appearance of a strong absorption line at 4100 cm⁻¹. Moreover, the concentration of the ACs in the irradiated diamond can be an order of magnitude higher than that observed previously in the darkest brown natural diamonds. A number of other absorption lines, including the H1b center at 4936 cm⁻¹ (0.612 eV) and new lines at ~5700 cm⁻¹ (0.706 eV) and 9320 cm⁻¹ (1.155 eV) not reported before in the literature, are observed, and their intensity evolutions at annealing temperatures are documented. At the highest fluences, all the lines show reduced intensities and broadening and spectral shifts due to a very high defect concentration and partial amorphization. The obtained experimental data can be used for the analysis of defect generation, transformations and healing in irradiated synthetic and natural diamonds. Full article

(This article belongs to the Special Issue Characterization of Disorder in Carbons (2nd Edition))

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13 pages, 5319 KiB

Open AccessArticle

Effective Elastic Modulus of Wavy Single-Wall Carbon Nanotubes

by Chensong Dong

C 2023, 9(2), 54; https://doi.org/10.3390/c9020054 - 26 May 2023

Viewed by 1128

Abstract

A simple method for determining the effective elastic modulus of wavy single-wall carbon nanotubes (SWCNTs) is presented in this paper. The effective modulus of curved SWCNTs is derived using Castigliano’s theorem. The effect of curvature on the effective modulus is studied. This method [...] Read more.

A simple method for determining the effective elastic modulus of wavy single-wall carbon nanotubes (SWCNTs) is presented in this paper. The effective modulus of curved SWCNTs is derived using Castigliano’s theorem. The effect of curvature on the effective modulus is studied. This method is verified by finite element analysis (FEA). The distributions of effective moduli are studied by Monte Carlo simulation. The effective modulus of a general wavy SWCNT is derived by considering the SWCNT as a number of curved SWCNT sections. Full article

(This article belongs to the Collection Nanocarbon-Based Composites and Their Thermal, Electrical, and Mechanical Properties)

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21 pages, 2335 KiB

Open AccessArticle

A New View on the Global Redox-Cycle of Biosphere Carbon

by A. A. Ivlev

C 2023, 9(2), 53; https://doi.org/10.3390/c9020053 - 23 May 2023

Viewed by 1244

Abstract

The global carbon cycle model is presented as a natural self-regulating machine that provides renewable biomass synthesis during evolution. The machine consists of two parts, geological and biosphere. Between the parts, there is an interaction. The geological part is controlled by the movement [...] Read more.

The global carbon cycle model is presented as a natural self-regulating machine that provides renewable biomass synthesis during evolution. The machine consists of two parts, geological and biosphere. Between the parts, there is an interaction. The geological part is controlled by the movement of lithosphere plates, which is under the guidance of gravitational forces from celestial bodies acting on the Earth. The movement of the lithosphere plates is divided into a phase of a relatively quick movement, occurring in the tectonically active state of the Earth’s crust, named the orogenic period, and a phase of a relatively slow movement, occurring in the phase of the tectonically quiet state of the crust, named geosynclinal period. In the orogenic period, the energy of moving plates’ collisions is sufficient to initiate sulfate reduction, proceeding in the subduction zone. This is the reaction where sedimentary organic matter is oxidized. Resultant CO₂ is injected into “atmosphere—hydrosphere” system of the Earth. Its concentration achieves maximal values, whereas oxygen concentration drops to a minimum since it reacts with the reduced sulfur forms that evolve in the thermochemical sulfate reduction and due to binding with reduced forms of metals, coming to the Earth’s surface with volcanic exhalations. Carbon dioxide initiates photosynthesis and the associated biosphere events. In the geosynclinal period, the sulfate reduction ceases, and CO₂ does not enter the system anymore, though photosynthesis in the biosphere proceeds in the regime of CO₂ pool depletion. Under such conditions, the surface temperature on the Earth decreases, ending with glaciations. The successive depletion of the CO₂ pool results in a regular sequence of climatic changes on the Earth. The ratio of CO₂/O₂ is the key environmental parameter in the orogenic cycle providing climatic changes. They consistently vary from hot and anaerobic in the orogenic period to glacial and aerobic by the end of the geosynclinal period. The climatic changes provide biotic turnover. Especially abrupt changes accompany the transition to a new orogenic cycle, resulting in mass extinction of organisms and the entry of huge masses of biogenic material into the sediment. This provided the conditions for the formation of rocks rich in organic matter (“black shales”). It is shown that the suggested model is supported by numerous geological and paleontological data evidencing the orogenic cycles’ existence and their relationship with the evolution of photosynthesis. Full article

(This article belongs to the Special Issue Permafrost and Carbon Dioxide Emission)

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17 pages, 6671 KiB

Open AccessArticle

Temperature- and Pressure-Reducing Regimes in the Growth Cell of HPHT Diamonds, Optimal for Preserving Crystal Integrity after Growth Completion

by Nikolay I. Alekseyev, Anton P. Broyko, Ivan K. Khmelnitskiy, Alexander V. Kolyadin, Vagarshak M. Aivazyan and Ivan V. Oreshko

C 2023, 9(2), 52; https://doi.org/10.3390/c9020052 - 18 May 2023

Viewed by 1452

Abstract

With its exceptional strength characteristics, diamond has some mechanical drawbacks, significant brittleness being among them. In particular, some HPHT-grown diamonds crack when the extreme parameters inherent to the diamond growth process gradually decrease. The cracking is caused by excessive stress due to the [...] Read more.

With its exceptional strength characteristics, diamond has some mechanical drawbacks, significant brittleness being among them. In particular, some HPHT-grown diamonds crack when the extreme parameters inherent to the diamond growth process gradually decrease. The cracking is caused by excessive stress due to the poor plastic properties of the diamond growth catalytic medium at certain stages of reducing the pressure and the temperature. An insulating container with the growth cell and heating circuit fragment inside can also make a significant contribution to the probability of cracking. This paper considers the possibility of minimizing the mechanical stress in the growth cell and, consequently, in the diamond crystal by choosing the optimal trajectory for the decrease in the pressure and temperature from diamond growth conditions to normal conditions. Full article

(This article belongs to the Special Issue Advanced in Low Dimensional Carbon: Processing and Applications)

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14 pages, 4486 KiB

Open AccessArticle

Ab Initio Study of Optical Properties of Hybrid Films Based on Bilayer Graphene and Single-Walled Carbon Nanotubes

by Michael M. Slepchenkov, Pavel V. Barkov, Dmitry A. Kolosov and Olga E. Glukhova

C 2023, 9(2), 51; https://doi.org/10.3390/c9020051 - 18 May 2023

Viewed by 1236

Abstract

In recent years, the possibility of combining graphene and carbon nanotubes has attracted much attention from researchers attempting to obtain new multifunctional hybrid materials with promising properties. Optoelectronics shows potential as a field of application for such hybrid structures. The variety of existing [...] Read more.

In recent years, the possibility of combining graphene and carbon nanotubes has attracted much attention from researchers attempting to obtain new multifunctional hybrid materials with promising properties. Optoelectronics shows potential as a field of application for such hybrid structures. The variety of existing structural configurations of graphene-nanotube hybrids requires preliminary detailed studies of their optical properties by computer simulation methods. In this paper, we consider island-type graphene-nanotube hybrid films formed by AB-stacked bilayer graphene and single-walled carbon nanotubes (SWCNTs). In this case, bilayer graphene is located above the surface of the nanotube, forming areas with an increased density of carbon atoms, creating so-called “islands.” To meet the conditions of a real experiment, we chose chiral SWCNTs (12,6) with a diameter of 1.2 nm, which are most often synthesized in real experiments. All constructed atomistic models of bilayer graphene-chiral SWCNT films were tested for thermodynamic stability at room temperature and proved their suitability for research. Using Kubo-Greenwood formalism, we calculated the complex optical conductivity tensor and absorbance coefficient in the wavelengths of ultraviolet, visible, and near-infrared radiations. The photocurrent spectra are calculated based on the obtained absorption spectra and solar radiation spectra on the earth’s surface (AM1.5) and outside the earth’s atmosphere (AM0). The results of calculations revealed regularities in the influence of structural parameters (nanotube diameter, graphene width) on the optical and optoelectronic properties of graphene-chiral SWCNT (12,6) with an island structure. Full article

(This article belongs to the Special Issue Advanced in Low Dimensional Carbon: Processing and Applications)

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20 pages, 8155 KiB

Open AccessArticle

Study of the Influence of Silicon-Containing Diamond-like Carbon Coatings on the Wear Resistance of SiAlON Tool Ceramics

by Marina A. Volosova and Anna A. Okunkova

C 2023, 9(2), 50; https://doi.org/10.3390/c9020050 - 16 May 2023

Viewed by 1175

Abstract

DLC coatings have low adhesive bond strength with the substrate and a high level of residual stresses. This paper is devoted to researching a complex of characteristics of a DLC-Si coating deposited on samples of SiAlON ceramics with intermediate coatings (CrAlSi)N pre-formed to [...] Read more.

DLC coatings have low adhesive bond strength with the substrate and a high level of residual stresses. This paper is devoted to researching a complex of characteristics of a DLC-Si coating deposited on samples of SiAlON ceramics with intermediate coatings (CrAlSi)N pre-formed to improve the adhesive bond strength employing vacuum-plasma spraying. DLC-Si coatings were formed by chemical vapor deposition in a gas mixture of acetylene, argon, and tetramethylsilane supplied through a multichannel gas purge system controlling the tetramethylsilane volume by 1, 4, 7, and 10%. The SiAlON samples with deposited (CrAlSi)N/DLC-Si coatings with different silicon content in the DLC layer were subjected to XPS and EDX analyses. Tribological tests were carried out under conditions of high-temperature heating at 800C. The nanohardness and elasticity modulus of the rational (CrAlSi)N/DLC-Si coating with Si-content of 4.1% wt. were 26 ± 1.5 GPa and 238 ± 6 GPa, correspondingly. The rational composition of (CrAlSi)N/DLC-Si coating was deposited on cutters made of SiAlON ceramics and tested in high-speed machining of aircraft nickel-chromium alloy compared to uncoated and DLC-coated samples. The average operating time (wear resistance) of (CrAlSi)N/DLC-Si(4.1% wt.)-coated end mills before reaching the accepted failure criterion was 15.5 min when it was 10.5 min for the original cutters. Full article

(This article belongs to the Collection Nanocarbon-Based Composites and Their Thermal, Electrical, and Mechanical Properties)

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17 pages, 4047 KiB

Open AccessArticle

Production, Characterization, and Activation of Biochars from a Mixture of Waste Insulation Electric Cables (WIEC) and Waste Lignocellulosic Biomass (WLB)

by Roberta Mota-Panizio, Ana Assis, Luís Carmo-Calado, Catarina Nobre, Andrei Longo, José Silveira, Maria Margarida Goncalves and Paulo Brito

C 2023, 9(2), 49; https://doi.org/10.3390/c9020049 - 09 May 2023

Viewed by 1417

Abstract

Waste insulation electrical cables (WIEC) currently do not have an added value, due to their physical–chemical characteristics. Carbonization is known to enhance feedstock properties, particularly fuel and material properties; as such, this article aimed to study the production and activation of biochars using [...] Read more.

Waste insulation electrical cables (WIEC) currently do not have an added value, due to their physical–chemical characteristics. Carbonization is known to enhance feedstock properties, particularly fuel and material properties; as such, this article aimed to study the production and activation of biochars using WIEC and lignocellulosic biomass wastes as feedstock. Biochars were produced in a ceramic kiln with an average capacity of 15 kg at different temperatures, namely 300, 350 and 400 °C. After production, the biochars were further submitted to a washing process with water heated to 95 °C ± 5 °C and to an activation process with 2 N KOH. All biochars (after production, washing and activation) were characterized regarding an elemental analysis, thermogravimetric analysis, heating value, chlorine removal, ash content, apparent density and surface area. The main results showed that the increase in carbonization temperature from 300 to 400 °C caused the produced biochars to present a lower amount of oxygen and volatile matter, increased heating value, greater chlorine removal and increased ash content. Furthermore, the activation process increased the surface area of biochars as the production temperature increased. Overall, the carbonization of WIEC mixed with lignocellulosic wastes showed potential in enhancing these waste physical and chemical properties, with prospects to yield added-value products that activates biochar. Full article

(This article belongs to the Special Issue Biomass—a Renewable Resource for Carbon Materials (2nd Edition))

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14 pages, 2657 KiB

Open AccessArticle

Efficient Heating of Activated Carbon in Microwave Field

by Ce Shi, Hongqing Shi, Hui Li, Hui Liu, Ehab Mostafa, Wenke Zhao and Yaning Zhang

C 2023, 9(2), 48; https://doi.org/10.3390/c9020048 - 08 May 2023

Cited by 4 | Viewed by 2269

Abstract

Activated carbon (AC) is widely utilized in water treatment, gas adsorption, and purification as well as the protection of environment due to the characteristics of prominent catalytic and adsorbent effect. The heating performances are therefore of significant importance for the further applications. The [...] Read more.

Activated carbon (AC) is widely utilized in water treatment, gas adsorption, and purification as well as the protection of environment due to the characteristics of prominent catalytic and adsorbent effect. The heating performances are therefore of significant importance for the further applications. The main objective of this study was therefore to detail the heating performance of activated carbon in microwave field, and the factors affecting the heating performance were also explored. In this study, the heating performance of AC as affected by microwave power (400, 450, 500, 550, and 600 W), feeding load (5, 10, 15, 20, and 25 g), and reactor volume (50, 100, 150, 200, and 250 mL) were detailed and reported. The results showed that when the microwave powers were 400, 450, 500, 550, and 600 W, the temperatures of AC increased to the desired value (about 200 °C) within 90, 85, 70, 60, and 35 s with average heating rates of 2.0, 2.2, 2.8, 3.0, and 5.9 °C/s, respectively. When the feeding loads were 5, 10, 15, 20, and 25 g, the temperatures of AC increased to desired temperature within 40, 70, 60, 50, and 50 s with average heating rates of 4.2, 2.8, 3.1, 3.50, and 3.55 °C/s, respectively. When the reactor volumes were 50, 100, 150, 200, and 250 mL, the temperatures of AC increased to the desired temperature within 25, 60, 70, 70, and 160 s with average heating rates of 7.6, 3.3, 2.8, 2.6, and 1.2 °C/s, respectively. In general, the faster heating rate of activated carbon was achieved at higher microwave power, more feeding load, and smaller reactor volume. Fitting formulae were given to predict the transient temperatures of AC in the microwave field, and the relative errors were in the ranges of −15.4~12.4%, −15.4~13.5% and −18.7~12.4% at different microwave powers, feeding loads, and reactor volumes, respectively. Full article

(This article belongs to the Special Issue Adsorption on Carbon-Based Materials)

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14 pages, 6355 KiB

Open AccessArticle

Fabrication of an Electrocatalyst Based on Rare Earth Manganites Incorporated with Carbon Nanofiber Hybrids: An Efficient Electrochemical Biosensor for the Detection of Anti-Inflammatory Drug Mefenamic Acid

by Saranvignesh Alagarsamy, Ruspika Sundaresan, Shen-Ming Chen, J. Meena Devi, Narendhar Chandrasekar and Balaji Ramachandran

C 2023, 9(2), 47; https://doi.org/10.3390/c9020047 - 06 May 2023

Cited by 4 | Viewed by 1869

Abstract

Pharmaceutical and personal care products are emerging as a new category of environmental pollution. Analytical drug detection from a biological sample for detection is still crucial today. Mefenamic acid (MA) is an anti-inflammatory drug utilized for its antipyretic and analgesic properties, which is [...] Read more.

Pharmaceutical and personal care products are emerging as a new category of environmental pollution. Analytical drug detection from a biological sample for detection is still crucial today. Mefenamic acid (MA) is an anti-inflammatory drug utilized for its antipyretic and analgesic properties, which is harmful to patients at higher dosages and is also recognized as a chemical pollutant that harms the environment. In this view, Dysprosium manganite/carbon nanofiber (DMO/CNF) was prepared by hydrothermal method for the electrochemical detection of MA. DMO/CNF/GCE exhibits high selectivity, excellent anti-interference, good stability, and reproducibility toward the detection of MA. The enhanced electrochemical performance of DMO/CNF/GCE was attributed to their synergetic interaction. Under optimized conditions, DMO/CNF/GCE shows a wide linear range of 0.01–741 μM and a low LOD of 0.009 μM. Satisfactory recoveries were obtained for human blood and tablet samples. Thus, the proposed DMO/CNF nanocomposite emerges as a promising material for the detection of MA. Full article

(This article belongs to the Special Issue Carbon Nanohybrids for Biomedical Applications)

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18 pages, 7665 KiB

Open AccessArticle

Recovery of Pd(II) Ions from Aqueous Solutions Using Activated Carbon Obtained in a Single-Stage Synthesis from Cherry Seeds

by Tomasz Michałek, Konrad Wojtaszek, Stanisław Małecki, Kamil Kornaus, Szymon Wandor, Julia Druciarek, Krzysztof Fitzner and Marek Wojnicki

C 2023, 9(2), 46; https://doi.org/10.3390/c9020046 - 28 Apr 2023

Cited by 1 | Viewed by 1737

Abstract

This paper describes a single-stage synthesis process for activated carbon using cherry seeds. The influences of the carbonization temperature and the time were investigated. Using the BET method, the surface area of the obtained activated carbons was determined, as well as the pore [...] Read more.

This paper describes a single-stage synthesis process for activated carbon using cherry seeds. The influences of the carbonization temperature and the time were investigated. Using the BET method, the surface area of the obtained activated carbons was determined, as well as the pore distribution, while SEM images provided further insight into the structure of the surface. Next, the adsorption isotherm was derived. For the test, Pd(II) chloride complex ions were used. It was found that the obtained activated carbon were suitable for palladium(II) recovery from diluted aqueous solutions. Out of the tested parameters of carbon synthesis, the most optimal one was found to be 500 °C for 3 h. Additionally, it was confirmed that the increase in the adsorption temperature affects the increase in palladium load from 1.6 mg/g at 20 °C to 15.6 mg/g at 50 °C (for the best-performing sample). This fact may suggest that the process of adsorption is associated with chemical reactions. Full article

(This article belongs to the Special Issue Adsorption on Carbon-Based Materials)

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10 pages, 10516 KiB

Open AccessArticle

Synthesis of Graphene Quantum Dots Coupled to Au Nanoparticles: A Facile and Versatile Route Using Different Carbon Sources

by David Ibarra, Oxana Kharissova and Idalia Gomez

C 2023, 9(2), 45; https://doi.org/10.3390/c9020045 - 27 Apr 2023

Cited by 1 | Viewed by 1961

Abstract

A top-down synthesis of graphene quantum dots (GQD) was carried out by hydrothermal method from different carbon sources (graphene, multi-walled carbon nanotubes, and black carbon) and

H_{2} O_{2}

as an oxidizing agent, with an N source added in the reaction to [...] Read more.

A top-down synthesis of graphene quantum dots (GQD) was carried out by hydrothermal method from different carbon sources (graphene, multi-walled carbon nanotubes, and black carbon) and

H_{2} O_{2}

as an oxidizing agent, with an N source added in the reaction to modify the chemical surface of the GQD, giving rise to the nanomaterial N-GQD. The modified chemical surface of N-GQD partially allowed the nucleation and coupling of gold nanoparticles from a

H A u C l_{4}

solution. The X-ray diffraction spectrogram confirms the amorphization of the precursor materials, while the functionalized surface of N-GQD was characterized through UV-Vis, Fourier transform infrared, and photoluminescense spectrometry; TEM and FE-SEM show particle sizes between 8 and 15 nm. N-GQD@AuNP presence can be confirmed by UV-Vis spectroscopy and TEM analysis, showing partial coupling and nanoparticle nucleation of Au in the structure with particle sizes between 20 and 40 nm. Full article

(This article belongs to the Special Issue Advanced in Low Dimensional Carbon: Processing and Applications)

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17 pages, 4111 KiB

Open AccessArticle

Application of Lolium multiflorum as an Efficient Raw Material in the Production of Adsorbent for Removal of Methylene Blue

by Elenara Oliveira da Silva, Alaor Valério Filho, Emanuelle Butato de Araujo, Taís Douglas Andrade, Maele Costa dos Santos, Ricardo Zottis, Gabriela Silveira da Rosa and André Ricardo Felkl de Almeida

C 2023, 9(2), 44; https://doi.org/10.3390/c9020044 - 26 Apr 2023

Cited by 3 | Viewed by 1539

Abstract

In this study, ryegrass straw agricultural residue (Lolium multiflorum L.) was employed as an adsorbent material to remove methylene blue (MB) dye from aqueous solutions. Four adsorbents were produced using phosphoric acid and pyrolysis as activating agents. The samples were analyzed with [...] Read more.

In this study, ryegrass straw agricultural residue (Lolium multiflorum L.) was employed as an adsorbent material to remove methylene blue (MB) dye from aqueous solutions. Four adsorbents were produced using phosphoric acid and pyrolysis as activating agents. The samples were analyzed with TGA, FTIR, SEM, and XRD techniques. A rapid adsorption of the MB was obtained with the ryegrass treated with 40% H₃PO₄, reaching equilibrium in 2 min. Moreover, a maximum adsorption capacity of 80.79 mg g⁻¹ and a removal efficiency of 99% were achieved. The results demonstrate a good performance of adsorbents from ryegrass for removing dye contaminants, such as methylene blue, from the aqueous solutions. Full article

(This article belongs to the Special Issue Carbons for Health and Environmental Protection)

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16 pages, 10060 KiB

Open AccessArticle

Lightweight Copper–Carbon Nanotube Core–Shell Composite Fiber for Power Cable Application

by Kavitha Mulackampilly Joseph, Kyle Brittingham, Vamsi Krishna Reddy Kondapalli, Mahnoosh Khosravifar, Ayush Arun Raut, Brett David Karsten, Hunter J. Kasparian, Nhat Phan, Arun Kamath, Amjad S. Almansour, Maricela Lizcano, Diana Santiago, David Mast and Vesselin Shanov

C 2023, 9(2), 43; https://doi.org/10.3390/c9020043 - 24 Apr 2023

Cited by 3 | Viewed by 2818

Abstract

The substitution of traditional copper power transmission cables with lightweight copper–carbon nanotube (Cu–CNT) composite fibers is critical for reducing the weight, fuel consumption, and CO₂ emissions of automobiles and aircrafts. Such a replacement will also allow for lowering the transmission power loss [...] Read more.

The substitution of traditional copper power transmission cables with lightweight copper–carbon nanotube (Cu–CNT) composite fibers is critical for reducing the weight, fuel consumption, and CO₂ emissions of automobiles and aircrafts. Such a replacement will also allow for lowering the transmission power loss in copper cables resulting in a decrease in coal and gas consumption, and ultimately diminishing the carbon footprint. In this work, we created a lightweight Cu–CNT composite fiber through a multistep scalable process, including spinning, densification, functionalization, and double-layer copper deposition. The characterization and testing of the fabricated fiber included surface morphology, electrical conductivity, mechanical strength, crystallinity, and ampacity (current density). The electrical conductivity of the resultant composite fiber was measured to be 0.5 × 10⁶ S/m with an ampacity of 0.18 × 10⁵ A/cm². The copper-coated CNT fibers were 16 times lighter and 2.7 times stronger than copper wire, as they revealed a gravimetric density of 0.4 g/cm³ and a mechanical strength of 0.68 GPa, suggesting a great potential in future applications as lightweight power transmission cables. Full article

(This article belongs to the Collection Novel Applications of Carbon Nanotube-Based Materials)

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17 pages, 2166 KiB

Open AccessArticle

Magnetic Field-Controlled Electrical Conductivity in AA Bilayer Graphene

by Vardan Apinyan and Tadeusz Kopeć

C 2023, 9(2), 42; https://doi.org/10.3390/c9020042 - 21 Apr 2023

Viewed by 1597

Abstract

We consider the effect of the external magnetic field on the in-plane conductivity in the AA-stacked bilayer graphene system in the strong excitonic condensate regime. We include the effects of the applied inter-layer electric field and the Coulomb interactions. The on-site and inter-layer [...] Read more.

We consider the effect of the external magnetic field on the in-plane conductivity in the AA-stacked bilayer graphene system in the strong excitonic condensate regime. We include the effects of the applied inter-layer electric field and the Coulomb interactions. The on-site and inter-layer Coulomb interactions were treated via the bilayer Hubbard model. Using the solutions for the physical parameters in the system, we calculate the in-plane conductivity of the bilayer graphene. By employing the Green-Kubo formalism for the polarization function in the system, we show that the conductivity in the AA bilayer system is fully controlled by the applied magnetic field. For the partial filling in the layers, the electrical conductivity is different for different spin orientations, and, at the high values of the magnetic field, only one component remains with the given spin orientation. Meanwhile, for the half-filling limit, there is no spin-splitting observed in the conductivity function. The theory evaluated here shows the new possibility for spin-controlled electronic transport in the excitonic bilayer graphene system. Full article

(This article belongs to the Special Issue Advances in Bilayer Graphene)

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9 pages, 1447 KiB

Open AccessArticle

Thermochemistry of the Smallest Hyperbolic Paraboloid Hydrocarbon: A High-Level Quantum Chemical Perspective

by Amir Karton

C 2023, 9(2), 41; https://doi.org/10.3390/c9020041 - 19 Apr 2023

Viewed by 1423

Abstract

[5.5.5.5]hexaene is a [12]annulene ring with a symmetrically bound carbon atom in its center. This is the smallest hydrocarbon with a hyperbolic paraboloid shape. [5.5.5.5]hexaene and related hydrocarbons are important building blocks in organic and materials chemistry. For example, penta-graphene—a puckered 2D allotrope [...] Read more.

[5.5.5.5]hexaene is a [12]annulene ring with a symmetrically bound carbon atom in its center. This is the smallest hydrocarbon with a hyperbolic paraboloid shape. [5.5.5.5]hexaene and related hydrocarbons are important building blocks in organic and materials chemistry. For example, penta-graphene—a puckered 2D allotrope of carbon—is comprised of similar repeating subunits. Here, we investigate the thermochemical and kinetic properties of [5.5.5.5]hexaene at the CCSD(T) level by means of the G4 thermochemical protocol. We find that this system is energetically stable relative to its isomeric forms. For example, isomers containing a phenyl ring with one or more acetylenic side chains are higher in energy by ∆H₂₉₈ = 17.5–51.4 kJ mol⁻¹. [5.5.5.5]hexaene can undergo skeletal inversion via a completely planar transition structure; however, the activation energy for this process is ∆H^‡₂₉₈ = 249.2 kJ mol⁻¹ at the G4 level. This demonstrates the high configurational stability of [5.5.5.5]hexaene towards skeletal inversion. [5.5.5.5]hexaene can also undergo a π-bond shift reaction which proceeds via a relatively low-lying transition structure with an activation energy of ∆H^‡₂₉₈ = 67.6 kJ mol⁻¹. Therefore, this process is expected to proceed rapidly at room temperature. Full article

(This article belongs to the Special Issue Characterization of Disorder in Carbons (2nd Edition))

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14 pages, 3881 KiB

Open AccessArticle

Arsenic, Iron, and Manganese Adsorption in Single and Trinary Heavy Metal Solution Systems by Bamboo-Derived Biochars

by Anawat Pinisakul, Nattakarn Kruatong, Soydoa Vinitnantharat, Ponwarin Wilamas, Rattikan Neamchan, Nareerat Sukkhee, David Werner and Saichol Sanghaisuk

C 2023, 9(2), 40; https://doi.org/10.3390/c9020040 - 16 Apr 2023

Cited by 4 | Viewed by 2129

Abstract

Currently, heavy metal-contaminated groundwater is an environmental concern. This study investigated the use of bamboo biochar, chitosan-impregnated biochar, and iron-impregnated biochar for arsenic, iron, and manganese removal from groundwater. Isotherms of arsenic, iron, and manganese adsorption by bamboo derived biochar were compared with [...] Read more.

Currently, heavy metal-contaminated groundwater is an environmental concern. This study investigated the use of bamboo biochar, chitosan-impregnated biochar, and iron-impregnated biochar for arsenic, iron, and manganese removal from groundwater. Isotherms of arsenic, iron, and manganese adsorption by bamboo derived biochar were compared with those of commercial activated carbon in simulated groundwater composed of single and trinary heavy metal solutions. The binding of heavy metals by virgin and loaded bamboo biochar and activated carbon was also investigated by sequential extraction. Chitosan and iron-impregnated biochar had enhanced arsenic adsorption, but these sorbents turned the pH of solution acidic, while it was alkaline for activated carbon. Adsorption equilibrium times of arsenic and iron were faster for single than trinary heavy metal systems because less ion competition occurred at active sites. The Langmuir model fitted the adsorption data well. The maximum adsorption capacities of arsenic, iron, and manganese by bamboo biochar in trinary heavy metal system were 2.2568, 0.6393, and 1.3541 mg g⁻¹, respectively. The main mechanism for arsenic removal was precipitation with iron. Bamboo biochar bound iron in organic and sulfide fractions and manganese with iron-oxide. Bamboo biochar can replace activated carbon as a more efficient and sustainable carbonaceous sorbent material for removal of mixed heavy metals from groundwater within acceptable pH ranges. Full article

(This article belongs to the Special Issue Biomass—a Renewable Resource for Carbon Materials (2nd Edition))

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13 pages, 3170 KiB

Open AccessArticle

A Composite Magnetosensitive Sorbent Based on the Expanded Graphite for the Clean-Up of Oil Spills: Synthesis and Structural Properties

by Vadim M. Kadoshnikov, Tetyana I. Melnychenko, Oksana M. Arkhipenko, Danylo H. Tutskyi, Volodymyr O. Komarov, Leonid A. Bulavin and Yuriy L. Zabulonov

C 2023, 9(2), 39; https://doi.org/10.3390/c9020039 - 12 Apr 2023

Cited by 1 | Viewed by 1745

Abstract

Oil spills necessitate the development of effective methods for preventing their damaging effects on the environment. A number of physical, chemical, thermal, and biological methods are used to combat oil spills. Among them, sorption is considered to be efficient in removing thin oil [...] Read more.

Oil spills necessitate the development of effective methods for preventing their damaging effects on the environment. A number of physical, chemical, thermal, and biological methods are used to combat oil spills. Among them, sorption is considered to be efficient in removing thin oil films from water surfaces. Currently, there is an urgent need for simple methods of obtaining oil sorbents that include a magnetosensitive component to optimize the process of removing oil from the water surface. The purpose of the work is to obtain and research oil sorbents resistant to destruction, with increased bulk density and complex magnetosensitivity, based on thermally expanded graphite (TEG) with the inclusion of micro- and nano-particles of iron and its oxides. The structure and composition of the new composite material was characterized using scanning electron microscopy, energy dispersive X-ray analysis, X-ray diffractometry, thermogravimetric analysis, and laser diffraction particle sizing. The composite sorbent comprised TEG with the inclusion of iron-containing magnetosensitive particles. Metal-carbon nanoparticles (MCN) were used as the magnetosensitive component; they had a magnetosensitive iron core covered with a carbon shell. We used two methods of synthesis, namely (i) mechanical mixing of the TEG flakes and MCN particles, and (ii) applying a thermal shock (microwave processing) to the mixture of graphite intercalated with sulphuric acid and micro- and nanoparticles of iron and iron oxides. In the first case, MCN particles were fixed on the faces, edges, and other surface defects of the TEG flakes due to intermolecular forces, coordinate bonds, and electrostatic interaction. The strong adhesion of magnetosensitive iron/iron oxide and TEG particles in the second case was due to the mutual dissolution of iron and carbon components during the thermal shock, which formed an interfacial layer in which iron carbide is present. The presence of magnetosensitive components in the structure of the proposed oil sorbents allows the use of magnetic separation for the localization and removal of oil spills, increases the density of sorbents, and, accordingly, leads to a decrease in windage while retaining the advantageous properties of thermally expanded graphite. According to the results of laboratory studies, the efficiency of removing oil from the water surface is not lower than 95–96%. Full article

(This article belongs to the Special Issue Carbons for Health and Environmental Protection)

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35 pages, 2977 KiB

Open AccessReview

Surface Functionalization of (Pyrolytic) Carbon—An Overview

by Lucija Pustahija and Wolfgang Kern

C 2023, 9(2), 38; https://doi.org/10.3390/c9020038 - 10 Apr 2023

Cited by 2 | Viewed by 2352

Abstract

This review focuses on techniques for modifying the surface of carbon that is produced from sustainable resources, such as pyrolytic carbon. Many of these materials display high specific surface area and fine particle distribution. Functionalization of a surface is a commonly used approach [...] Read more.

This review focuses on techniques for modifying the surface of carbon that is produced from sustainable resources, such as pyrolytic carbon. Many of these materials display high specific surface area and fine particle distribution. Functionalization of a surface is a commonly used approach in designing desired surface properties of the treated material while retaining its bulk properties. Usually, oxidation is a primary step in carbon functionalization. It can be performed as wet oxidation, which is a type of chemical surface modification. Wet oxidation is usually performed using nitric acid and hydrogen peroxide, as well as using hydrothermal and solvothermal oxidation. On the other side, dry oxidation is representative of physical surface modification. This method is based on corona discharge and plasma oxidation which are promising methods that are in line with green chemistry approaches. Whilst the oxidation of the carbon surface is a well-known method, other chemical modification techniques, including cycloadditions and various radical reactions on graphene layers, are presented as an alternative approach. Regarding secondary functionalization, coupling organosilanes to activated carbon is a common technique. Organosilanes bearing reactive groups present a bridge between inorganic species and polymer systems, e.g., epoxy and polyurethane resins, and facilitate the use of carbonaceous materials as reinforcing components for polymers and thermosetting resins. Along with the presented functionalization methods, this review also provides an overview of new applications of modified (i.e., functionalized) carbon materials, e.g., for the building industry, wastewater treatment, semiconducting materials and many more. Full article

(This article belongs to the Section Carbon Materials and Carbon Allotropes)

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17 pages, 33112 KiB

Open AccessArticle

Replacing Lime with Rice Husk Ash to Reduce Carbon Footprint of Bituminous Mixtures

by Raja Mistry, Tapash Kumar Roy, Sand Aldagari and Elham H. Fini

C 2023, 9(2), 37; https://doi.org/10.3390/c9020037 - 27 Mar 2023

Viewed by 2078

Abstract

There have been several emphasized pathways toward a reduction in carbon footprint in the built environment such as recycling, technologies with lower energy consumption, and alternative materials. Among alternative materials, bio-based materials and nature inspired solutions have been well-received. This study examines the [...] Read more.

There have been several emphasized pathways toward a reduction in carbon footprint in the built environment such as recycling, technologies with lower energy consumption, and alternative materials. Among alternative materials, bio-based materials and nature inspired solutions have been well-received. This study examines the merits of using rice husk ash as a replacement for lime; lime has a high carbon footprint mainly associated with the decomposition of calcium carbonate to calcium oxide to form lime. Lime is commonly used in bituminous composites for roadway construction to mitigate their susceptibility to moisture damage. Replacing lime with a low-carbon alternative could allow a reduction in CO₂ equivalent of bituminous composites. This paper studies the merits of using rice husk ash (RHA) as a substitute for conventional hydrated lime (HL) in bituminous composites. It should be noted that rice industries burn rice husks in a boiler as fuel, generating a substantial volume of RHA. The disposal of this ash has major environmental impacts associated with the contamination of air and water. Here, we study physical and chemical characteristics of both HL and RHA for use in bitumen mixtures. This was followed by examining the extent of dispersion of each filler in bitumen via optical microscopy to ensure their uniform dispersion. The properties of the mixtures were further studied using the Marshall mix design method. It was found that a 25.67% increase in Marshall stability and a 5.95% decrease in optimum binder content were achieved when HL was replaced by RHA at 4% filler concentration. In addition, mixtures containing RHA exhibited higher resistance to cracking and permanent deformation compared to mixtures containing HL. Additionally, 4% RHA in the mix showed stripping resistance similar to the conventional mix with HL. The mixture with 4% RHA had a lower carbon footprint with enhanced economic and environmental impacts compared to the conventional mix with HL. The study results provide insights pertaining to the merits of bio-based materials to reduce the carbon footprint of pavements. Full article

(This article belongs to the Special Issue Biomass—a Renewable Resource for Carbon Materials (2nd Edition))

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