Thermal Carbon Research Articles

Assessment of Pretreatments for Highly Concentrated Leachate Waters to Enhance the Performance of Catalytic Wet Peroxide Oxidation with Sustainable Low-Cost Catalysts

Matured compost, derived from a mechanical and biological treatment (MBT) plant, was used as a precursor to produce catalysts through hydrothermal and thermal carbonization, HC and PC, respectively. HC and PC displayed suitable properties to act as catalysts in the catalytic wet peroxide oxidation (CWPO) treatment of the highly polluted leachate waters generated in the same MBT plant (TOC0 = 27 g L−1; COD0 = 60 g L−1; BOD5,0 = 23 g L−1). The influence of catalyst loading and pH were studied, considering multiple additions of H2O2. The best experimental conditions found were T = 80 °C, pH0 = 3.0, 7.2 g L−1 of HC catalyst, 85.7 g L−1 of H2O2, added in five batches in one-hour intervals between each addition. Under these experimental conditions, removals of 43%, 52%, 93%, 82%, 35%, 95% and 93% for the COD, TOC, BOD5, aromaticity, chlorides, turbidity and color number (CN) were, respectively, observed. Ion exchange resins and coagulation–flocculation were studied as pretreatment options to reduce the complexity of the leachate waters and enhance the CWPO results. Both strategies resulted in higher mineralization and enhanced the consumption efficiency of H2O2 (ηH2O2). The sequential treatment using coagulation–flocculation and CWPO with PC catalyst showed the best results, achieving abatement of 94%, 70%, 98%, 93%, 31%, 96% and 95% for COD, TOC, BOD5, aromaticity, chlorides, turbidity and CN, respectively.

Manufacturing and characterisation of a new thermal pre-stressed carbon fibre-reinforced lattice core for sandwich panels

Development of high-performance sandwich structures is particularly attractive for aerospace applications, where novel lighter materials and structures are object of extensive research. This work is focused on the design of a new high-performance Carbon FRP core as alternative to traditional periodic prismatic ones. The innovative core is designed as a 2D close-packing pattern of circular cells and manufactured by connecting pre-preg corrugated laminates in specific locations. The corrugated laminates are layered following an asymmetric sequence in order to generate residual thermal stresses within the core to enhance energy absorption and compressive properties. The distribution of the residual thermal stress within the core was numerically studied with a finite element model of the unit cell, in order to prove the positive contribution of the asymmetric layup on the mechanical properties and study the failure mechanisms of the unit-cell. Composite core samples were manufactured, and their mechanical properties were experimentally evaluated through compression, both out-of-plane and in-plane, and beam flexure tests. Results were compared in terms of specific properties with traditional aluminium honeycomb core, showing large increments of specific compressive strength (+84.6%), in-plane compressive modulus (over +500%), Specific Energy Absorption (+145%) and shear (>20%). The FEM model was validated against experimental compressive results, showing an error below 10%. The results show that the core is suitable for applications in novel high-performance sandwich structures, leading to numerous advantages in comparison to traditional cores, such as higher specific properties, manufacturability of complex sandwich structures and higher adhesion and compatibility with CFRP skins.

Comparative Study of Metal Substrates for Improved Carbonization of Electrospun PAN Nanofibers.

Carbon nanofibers are used for a broad range of applications, from nano-composites to energy storage devices. They are typically produced from electrospun poly(acrylonitrile) nanofibers by thermal stabilization and carbonization. The nanofiber mats are usually placed freely movable in an oven, which leads to relaxation of internal stress within the nanofibers, making them thicker and shorter. To preserve their pristine morphology they can be mechanically fixated, which may cause the nanofibers to break. In a previous study, we demonstrated that sandwiching the nanofiber mats between metal sheets retained their morphology during stabilization and incipient carbonization at 500 °C. Here, we present a comparative study of stainless steel, titanium, copper and silicon substrate sandwiches at carbonization temperatures of 500 °C, 800 °C and 1200 °C. Helium ion microscopy revealed that all metals mostly eliminated nanofiber deformation, whereas silicone achieved the best results in this regard. The highest temperatures for which the metals were shown to be applicable were 500 °C for silicon, 800 °C for stainless steel and copper, and 1200 °C for titanium. Fourier transform infrared and Raman spectroscopy revealed a higher degree of carbonization and increased crystallinity for higher temperatures, which was shown to depend on the substrate material.

Thermal response of the two-directional high-thermal-conductive carbon fiber reinforced aluminum composites with low interface damage by a vacuum hot pressure diffusion method

A two directional high thermal conductive carbon fiber reinforced aluminum matrix composite with low interface damage is prepared by a vacuum hot-pressure diffusion method using the mesophase-pitch-based carbon fiber (CFMP) cloth as fast heat conduction channels. The fiber/matrix interface is composed of an amorphous gradient transition layer between aluminum matrix and CFMP rather than Al4C3 interface phase, thus endowing the continuous heat conduction channels in the composite. The composites deliver the high thermal conductivity of 305.5 W∙m−1∙K−1 in the X (Y) direction and the low volume density of only 2.53 g∙cm−3 when the fiber volume fraction reaches 30 vol%. The high thermal conductivity of the composite is attributed to the highly oriented fast heat transfer effect of the CFMP, the isotropic heat transfer effect of the aluminum matrix and the low-damage CFMP/aluminum interface. This study opens a new avenue to design and select the high thermal conductivity and lightweight thermal management materials for the aerospace field.

Feasibility analysis of using novel Sepanta biodiesel fuel as an additive to gas micro‐turbine fuels: An experimental study

AbstractThe population growth, causing the increasing energy demand, the lack of fossil fuels, and its pollution, has become the most important human challenges in years. One of the main goals in using fossil fuels is electricity generation in the utilities, as they can be used in many different types. Gas power plants are one of the ways of generating electricity in many areas, and they are based on gas turbines. The current study aims to define a novel biodiesel fuel named, Sepanta; to improve the combustion conditions of diesel fuel in a gas turbine by using an Iranian endemic plant: Salvia leriifolia seeds oil. In the present research, Sepanta biodiesel has been added to the diesel Euro 4 in different concentrations (20%, 40%, and 60%). Firstly, to determine the differentiation of Sepanta fuel from pure diesel, experiments were carried out such as determining the thermal value and carbon percentage, hydrogen, nitrogen, and oxygen determination in the fuel mixed with Sepanta, and then, in the lake of Sepanta, using the pure diesel, determination of the optimal points has been carried out. The results showed the use of 60% Sepanta reduced the 27% release of unburned hydrocarbons and the use of 40% Sepanta reduced 33% nitrogen oxides in the way to approve the ideal Sepanta performance as an additive to the defined biodiesel.

Performance evaluation of coated carbon foam material in heat exchanger applications

The overall decrease in the size and the weight of electronic components has led to high power dissipation and the need for innovative cooling designs. The current work presents an experimental study that has been conducted to use several types of pristine and coated carbon foams as heat sink and heat exchanger in a thermoelectric cooler for cooling vest application. Various parameters were measured and calculated to investigate the performance of carbon foam. Such parameters are weight, effective thermal conductivity, mass flowrate, the outlet temperature for both heat sink, and heat exchanger in addition to their temperature difference. The results from this work were compared to a previous study conducted on aluminum fins. The results showed that the coating technique improved the thermal conductivity of the foam with low thermal conductivity more than the foam with high thermal conductivity. The performance of carbon foam was much better than aluminum in dissipating the heat, especially for the high thermal conductive carbon foam. The largest weight value of the foam was around 70% of aluminum fins, while its thermal conductivity was 300% more. The foam has the potential to improve heat transfer, thus reducing the size and the weight of equipment while simultaneously increasing its efficiency and capabilities.

Continuous measurement of K and S release by means of ETV-ICP OES for high-temperature coal conversion processes

To estimate the fouling, slagging and corrosion potential of an energy feedstock during thermal carbon conversion processes, it is necessary to determine the temperature-dependent release behavior of relevant elements such as potassium and sulfur. For this purpose, this study employed electrothermal evaporation with inductively coupled plasma and optical emission spectroscopy (ETV-ICPOES) to investigate the element release in atmospheres containing oxygen both qualitatively and quantitatively. Using three different coal samples, it is shown that different heating rates (5–350 K/s) and gas atmospheres (0–10 vol-% O2 in the Ar gas stream) lead to differences in the release behavior. More sulfur is released when the oxygen content increases, whatever the sample. The release of potassium, on the other hand, depends on the sample matrix and the secondary reactions that occur. In two of the samples investigated, K is bound to silicates. These samples tend to form slags in which the potassium can bind. In the third sample, the potassium is organically bound or is bound to exchange sites on clay minerals and is released almost completely during the analyses.

Day-Ahead DSM-Integrated Hybrid-Power-Management-Incorporated CEED of Solar Thermal/Wind/Wave/BESS System Using HFPSO

This paper presents a day-ahead demand-side management (DSM)-integrated hybrid power management algorithm (PMA) with an objective of combined economic and emission load dispatch (CEED) considering losses. The algorithm was tested on an IEEE 30-bus six-generator system consisting of solar thermal/wind/wave/battery energy storage systems (BESSs) considering real-time data of the Gujarat (19°07′ N, 72°51′ E) coastal region and diverse renewable energy (RES) and storage sources. A maiden attempt of utilizing hybrid firefly particle swarm optimization (HFPSO) to reduce thermal energy consumption and carbon emission was presented. Further, a novel attempt for a versatile renewable power management system was proposed based on a day-ahead pricing scheme to manage load demand and generation effectively. The PMA permits the users to bring down the general load demand and adjust the load curve during the peak time frame. The comparative performance of particle swarm optimization (PSO), firefly algorithm (FA), and HFPSO algorithms in solving the objective was presented. The HFPSO algorithm was found to be the best in terms of a fuel cost of 544.160 (USD/h), emission 20.301 (kg/h), and peak-load reduction of 31.292%, 24.210%, and 51.197% for residential, commercial, and industrial loads, respectively, when contrasted with the other two algorithms PSO and FA.

Effects of Different Ethanol/Diesel Blending Ratios on Combustion and Emission Characteristics of a Medium-Speed Diesel Engine

In order to better evaluate the effects of ethanol/diesel blends on engine combustion and emission characteristics, we developed an engine cylinder model using the software CONVERGE combined with the program CHEMKIN. The model was validated experimentally. A modified chemical kinetic mechanism was used to calculate the combustion process of diesel fuel and ethanol for the diesel engine, including 154 reactions and 68 species. Furthermore, the influence of different ethanol proportions on diesel engine combustion and emission characteristics, including power, brake specific fuel consumption, brake thermal efficiency, cylinder pressure, cylinder temperature, nitrogen oxide (NOx), carbon monoxide (CO), and soot emissions, was also investigated. Our results showed that cylinder pressure and temperature increased with increased ethanol content. When the ethanol content increased to 20% at 100% load, the cylinder pressure increased by 0.46%, and the thermal efficiency increased by 3.63%. However, due to the lower calorific value of ethanol, the power decreased by 4.12%, and the brake specific fuel consumption increased by 4.23%. In addition, the ethanol/diesel blends significantly reduced CO and soot emissions. Compared with diesel, soot and CO emissions from the D80E20 at 100% load reduced by 63.25% and 17.24%, respectively. However, NOx emission increased by 1.39%.

Pyrolysis of fast growing wood Macaranga gigantea: Product characterisation and kinetic study

Fast-growing wood Macaranga gigantea has been pyrolyzed and its pyrolysis products have been characterized and their formation kinetics studied. Pyrolysis of M. gigantea wood was carried out by varying the temperature and time of pyrolysis to determine the effect of these two parameters on product yields and product characteristics. In general, an increase in pyrolysis temperature and time increased the yield of liquid and gas products, the concentration of cellulose, hemicellulose and lignin-derived compounds, but decreased the biochar yield. The organic phase liquid pyrolysis products mainly contained phenolic compounds and their derivatives, eugenols, furans, aldehydes and ketones. Fourier-transform infrared spectroscopy and pyrolysis–gas chromatography–mass spectrometry analyses of biochar showed that thermal decomposition of M. gigantea required temperatures higher than 300 °C to optimize thermal decomposition and carbonization of lignin, cellulose and hemicellulose. The concentration of phenols and benzenediols in biochar decreased with an increase in pyrolysis temperature. M. gigantea pyrolysis kinetics studies showed that wood pyrolysis occurred through four main stages with activation energy (Eα) values, based on calculations by the Friedman and Kissinger-Akahira-Sunose methods, of 28.1–99.0 kJ/mol and 35.6–104.9 kJ/mol, respectively. The spectra produced by thermogravimetric analyzer coupled with a Fourier-transform infrared spectroscopy showed that H2O and CO2 were produced during pyrolysis and the volatile compounds produced were predominantly phenolic compounds, in accord with characterization results of the liquid products by gas chromatography–mass spectrometry and nuclear magnetic resonance spectroscopy.

Tailoring the Stabilization and Pyrolysis Processes of Carbon Molecular Sieve Membrane Derived from Polyacrylonitrile for Ethylene/Ethane Separation.

For ethylene/ethane separation, a CMS (carbon molecular sieve) membrane was developed with a PAN (polyacrylonitrile) polymer precursor on an alumina support. To provide an excellent thermal property to PAN precursor prior to the pyrolysis, the stabilization as a pre-treatment process was carried out. Tuning the stabilization condition was very important to successfully preparing the CMS membrane derived from the PAN precursor. The stabilization and pyrolysis processes for the PAN precursor were finely tuned, and optimized in terms of stabilization temperature and time, as well as pyrolysis temperature, heating rate, and soaking time. The PAN stabilized at >250 °C showed improved thermal stability and carbon yield. The CMS membrane derived from stabilized PAN showed reasonable separation performance for ethylene permeance (0.71 GPU) and ethylene/ethane selectivity (7.62), respectively. Increasing the pyrolysis temperature and soaking time gave rise to an increase in the gas permeance, and a reduction in the membrane selectivity. This trend was opposite to that for the CMS membranes derived from other polymer precursors. The optimized separation performance (ethylene permeance of 2.97 GPU and ethylene/ethane selectivity of 7.25) could be achieved at the pyrolysis temperature of 650 °C with a soaking time of 1 h. The separation performance of the CMS membrane derived from the PAN precursor was comparable to that of other polymer precursors, and surpassed them regarding the upper bound trade off.

Value-Added Bio-carbon Production through the Slow Pyrolysis of Waste Bio-oil: Fundamental Studies on Their Structure-Property-Processing Co-relation.

The present work addresses the transformation of bio-oil into valuable biocarbon through slow pyrolysis. The biocarbons produced at three different temperatures (400, 600, and 900 °C), 10 °C min–1 heating rate, and 30 min holding time were tested for their surface morphology, thermal stability, elemental composition, functionality, particle size, and thermal and electrical conductivity. The physicochemical study of bio-oil showed substantial carbon content, higher heating value, and lower nitrogen content. Also, the Thermogravimetric analyzer–FourierTransform Infrared Spectroscopy (TGA-FTIR) study of bio-oil confirmed that the majority of gases released were hydrocarbons, carbonyl products, ethers, CO, and CO2, with a minor percentage of water and alcohol. Overall, it was found that the pyrolysis temperature has the dominant role in the yield and properties of biocarbon. The physicochemical characterization of biocarbon showed that the higher temperature based pyrolyzed biocarbon (600 and 900 °C) improved the properties in terms of thermal stability, thermal conductivity, graphitic content, ash content, and carbon content. Furthermore, the elemental and Energy-Dispersive Spectroscopy study of biocarbon confirmed the substantial depletion in oxygen and hydrogen at a higher temperature (600 and 900 °C) than the lower temperature based pyrolyzed biocarbon (400 °C). Additionally, the purest form of the biocarbon is found at a higher temperature (900 °C) with higher thermal stability and carbon content. The study of the surface morphology of biocarbon revealed that the higher temperature (600 and 900 °C) biocarbon showed larger and harder particles than the lower temperature biocarbon (400 °C); however, the electrical conductivity of biocarbon decreased, whereas thermal conductivity increased, with an increase in the pyrolysis temperatures. Moreover, the particle size analysis of biocarbon confirmed that most of the particles were found in the range of 1 μm. The increased thermal stability, carbon content, and graphitic content and the lower ash content endorse biocarbon as an excellent feedstock for carbon-based energy storage materials.

Semi-conducting microspheres formed from glucose for semi-active electric field-responsive electrorheological systems.

In this study glucose particles were successfully transformed to conducting carbonaceous microspheres through sequential hydrothermal and thermal carbonization. The prepared carbonaceous particles were thereafter used as a dispersed phase in a novel electrorheological fluid. Due to significant enhancements of the conductivity and dielectric properties when compared with the glucose precursor, the prepared electrorheological fluid based on carbonaceous microspheres exhibited a yield stress of over 200 Pa at a particle concentration of 5 wt% at an electric field intensity of 3 kV mm-1, and overcomes recently published novel electrorheological fluids and others based on carbonized particles. In order to estimate the exact rheological parameters, the measured data were treated using a mathematical model Cho-Choi-Jhon, and the reproducibility and reversible possibility to control the viscosity of the novel prepared electrorheological fluid were confirmed through time dependence tests at various electric field intensities. Not only did this approach lead to carbonaceous conducting particles with high performance in electrorheology, but the yield after carbonization at 500 °C was also 60%. It was thus confirmed that unique carbonaceous conducting particles were prepared using a sustainable method giving high yields, and can be potentially used in many other applications where such carbonaceous particles are required.

Review of thermal performance, hygrothermal behavior, and carbon sequestration in hemp concrete in order to make it an energy-efficient and eco-friendly material

Review of thermal performance, hygrothermal behavior, and carbon sequestration in hemp concrete in order to make it an energy-efficient and eco-friendly material

Evaluating the economic viability of NGCC-SWITCC: Natural Gas Combined Cycle System With Integrated Thermal storage and Carbon Capture

Evaluating the economic viability of NGCC-SWITCC: Natural Gas Combined Cycle System With Integrated Thermal storage and Carbon Capture

Diazines on graphene: adsorption, structural variances and electronic states.

We conduct quantum studies of adsorption of diazine heterocycles on graphene to discuss experimental thermodynamics of gas-phase adsorption of pyridazine, pyrimidine and pyrazine on graphitized thermal carbon black, as reported previously. Using Born-Oppenheimer molecular dynamics and density functional studies, we characterize structural and electronic tendencies of the heterocycles on graphene. The theoretical studies predict the adsorption of pyridazine, pyrazine and pyrimidine to cause electronic perturbations of dipole, quadrupole and mixed spatial characters, respectively, resulting in a red shift of the electronic components of the heterocycles to modulate graphene electronics upon admixing of diazine orbital components with the πz states of the substrate. Investigating the thermodynamics of adsorption further involves calculating Henry's constant with the expression of the uniform surface limit: using experimental data, we estimate binding energies and force derivatives with respect to the surface normal. The extracted association energies agree with the results of Lennard-Jones potential calculations. Together, the reported pyridazine anomalous retention required the association force constant to be lower compared with values for the other diazines. Exploring energies of intermolecular relations, we ascribe the pyridazine anomalous retention to possibility of the formation of pyridazine dimers: when on the surface, only for pyridazine, the computed benefit of pairing is larger than the energy of molecular association with graphene.

Opportunities for Catalytic Reactions and Materials in Buildings

Residential and commercial buildings are responsible for over 30% of global final energy consumption and accounts for ~40% of annual direct and indirect greenhouse gas emissions. Energy efficient and sustainable technologies are necessary to not only lower the energy footprint but also lower the environmental burden. Many proven and emerging technologies are being pursued to meet the ever-increasing energy demand. Catalytic science has a significant new role to play in helping address sustainable energy challenges, particularly in buildings, compared to transportation and industrial sectors. Thermally driven heat pumps, dehumidification, cogeneration, thermal energy storage, carbon capture and utilization, emissions suppression, waste-to-energy conversion, and corrosion prevention technologies can tap into the advantages of catalytic science in realizing the full potential of such approaches, quickly, efficiently, and reliably. Catalysts can help increase energy conversion efficiency in building related technologies but must utilize low cost, easily available and easy-to-manufacture materials for large scale deployment. This entry presents a comprehensive overview of the impact of each building technology area on energy demand and environmental burden, state-of-the-art of catalytic solutions, research, and development opportunities for catalysis in building technologies, while identifying requirements, opportunities, and challenges.

Synthesis and characterization of high-performance ZnO/graphene quantum dot composites for photocatalytic degradation of metronidazole

BackgroundIndustrial and medical wastewater treatment has been the focus of significant research and development in recent years. Especially untreated antibiotics commonly found within the wastewater generated by the hospitals or/and manufacturers have caused serious environmental concerns. MethodsIn this work, we proposed a heterogeneous graphene quantum dot (GQD)/ZnO composite as a photocatalyst for degrading antibiotics by using co-precipitation and thermal carbonization processes. Significant findingsThe introduction of N-GQDs efficiently facilitates the photocatalytic activity and reaction rate. Indeed, the N-functionalized GQDs, including pyrrolic/pyridinic N and graphitic N, can accelerate the charge transfer rate in the heterostructures. Optimizing the composition of GQD/ZnO catalyst, ultra-high removal ratio (∼100%) and significantly improved rate constant (i.e., 1.74 times higher compared to pristine ZnO) was achieved. In the binary catalyst, the presence of N-GQDs enhances the absorption in visible-light region and increases the photo-induced charge carrier, resulting in an elevated photocatalytic activity. This finding reveals that the GQD/ZnO composite structure demonstrated in this work can be employed as an in-expensive photocatalyst for degrading metronidazole (MNZ) in liquid phase under the UV-light irradiation.

Bi-Functional Paraffin@Polyaniline/TiO2/PCN-222(Fe) Microcapsules for Solar Thermal Energy Storage and CO2 Photoreduction.

A novel type of bi-functional microencapsulated phase change material (MEPCM) microcapsules with thermal energy storage (TES) and carbon dioxide (CO2) photoreduction was designed and fabricated. The polyaniline (PANI)/titanium dioxide (TiO2)/PCN-222(Fe) hybrid shell encloses phase change material (PCM) paraffin by the facile and environment-friendly Pickering emulsion polymerization, in which TiO2 and PCN-222(Fe) nanoparticles (NPs) were used as Pickering stabilizer. Furthermore, a ternary heterojunction of PANI/(TiO2)/PCN-222(Fe) was constructed due to the tight contact of the three components on the hybrid shell. The results indicate that the maximum enthalpy of MEPCMs is 174.7 J·g−1 with encapsulation efficiency of 77.2%, and the thermal properties, chemical composition, and morphological structure were well maintained after 500 high–low temperature cycles test. Besides, the MEPCM was employed to reduce CO2 into carbon monoxide (CO) and methane (CH4) under natural light irradiation. The CO evolution rate reached up to 45.16 μmol g−1 h−1 because of the suitable band gap and efficient charge migration efficiency, which is 5.4, 11, and 62 times higher than pure PCN-222(Fe), PANI, and TiO2, respectively. Moreover, the CO evolution rate decayed inapparently after five CO2 photoreduction cycles. The as-prepared bi-functional MEPCM as the temperature regulating building materials and air purification medium will stimulate a potential application.

Ecosystem-based adaptation to climate change through residential urban green structures: co-benefits to thermal comfort, biodiversity, carbon storage and social interaction

Climate change adaptation is essential to mitigate risks, such as extreme weather events triggered by global warming and amplified in dense urban environments. Ecosystem-based adaptation measures, such as urban greening, are promoted in cities because of their flexibility and their positive side effects, such as human health benefits, ecological effects, climate mitigation and a range of social benefits. While individual co-benefits of greening measures are well studied, often in public green spaces, few studies quantify co-benefits comprehensively, leaving social benefits particularly understudied. In this study, we perform biophysical and socio-cultural assessments of co-benefits provided by semi-public, residential greening in four courtyards with varying green structures. We quantify effects on thermal comfort, biodiversity, carbon storage and social interaction. We further assess the importance of these co-benefits to people in the neighbourhood. Subsequently, we weight the results from the biophysical assessments with the socio-cultural values to evaluate how even small differences in green structures result in differences in the provision of co-benefits. Results show that, despite relatively small differences in green structures, the residential courtyards with a higher green volume clearly generate more co-benefits than the residential yards with less green, particularly for thermal comfort. Despite differences in the valuation of co-benefits in the neighbourhood, socio-cultural weights did not change the outcome of the comparative assessment. Our results highlight that a deliberate management strategy, possibly on neighbourhood-scale, could enhance co-benefits and contribute to a more sustainable urban development.