Increase In Carbonization Time Research Articles

Durability of Concrete Under the Combined Action of Carbonization and Fatigue Loading of Vehicles

Natural factors such as environments gradually cause the aging of structural materials of concrete bridges and mechanical properties of the components are constantly degraded. When highway bridge structures are under the combined with vehicle loading and environmental diversities, the degradation of structural performance is further aggravated. In this study, according to the deterioration trend of concrete durability in atmospheric environment, durability tests for concrete under the combined action of fatigue loading of vehicles and carbonization were performed by artificial climate simulation. A bending fatigue test for concrete under vehicle loading was carried out, and the trend of fatigue life change with vehicle loading level and the trend of fatigue strain development were obtained. The results show that the fatigue life increases with the decrease in fatigue loading level of vehicles, and the logarithmic value of fatigue life Nf is linear with the fatigue stress level S. Fast carbonization tests for concrete were performed with respect to the fatigue damage degree D of 0, 0.2, 0.4, 0.6, and 0.8. It was found that the carbonization trend of fatigue damaged concrete under vehicle loading follows the Fick first law. The carbonization depth increases with the increase in carbonization time, relatively fast at the initial stage and then slowly at the later stage. When the fatigue damage degree D is less than 0.4, the effects of fatigue damage on carbonization is relatively small. When D is more than 0.4, the effect of fatigue damage on carbonization is relatively significant. The extension of interior micro-cracks and micropores caused by fatigue damage is a significant factor affecting the carbonization performance of fatigue damaged concrete. The change trend of carbonization depth of damaged concrete with time was fitted and analyzed. An influencing factor of fatigue damage was introduced, and a durability prediction model for concrete under the combined action of carbonization and fatigue loading of vehicles was established.

Unusual Thermal Conductivity of Carbon Nanosheets with Self-Emerged Graphitic Carbon Dots.

The thermal conductivity (κ) of two-dimensional conducting and transparent carbon nanosheets (CNSs) prepared by a catalyst- and transfer-free process is calculated for the first time by the optothermal Raman technique. A systematic structural analysis of CNSs reveals that the thickness of polymer films affects the interaction between molecules and a Si wafer significantly, thus helping to determine the ratio of sp2 and sp3 bonding configurations of carbon (C) atoms in the CNS. Notably, the holding time of carbonization can realize a hierarchical structure with graphitic carbon dots emerging from the CNS through the rearrangement of carbon atoms, leading to the excellent κ value of 540 W/(m·K) at 310 K. It is demonstrated that an appropriate increase in carbonization time can be an effective approach for improving the ratio of sp2- to sp3-bonded C atoms in the CNS. The thermal conductivity of the CNS with the highest ratio of sp2- to sp3-bonded C atoms exhibits superior behavior and is comparable to that of reduced graphene oxide and supported graphene, respectively. Finally, when the CNS with the highest κ value of 540 W/(m·K) was applied to a heater as the heat-dissipating material, the heater showed the temperature decrease by 14 °C compared to the case without the CNS. The catalyst- and transfer-free approach for the synthesis of CNSs is highly desirable for use as heat sink materials or substrates with heat dissipation functions for extensively integrated electronic devices.

Developing Lignosulfonate-Based Activated Carbon Fibers

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

Preparation and characterization of nanocarbons from <i>Nicotiana tabacum stems</i>

Nanocarbon materials can improve adsoption capacity if the nano size range is optimized during production. In this study, nanocarbons were prepared from green recyclable waste N. tabacum stem using carbonization process and KOH as the activating agent, thus potentially unclocking value in the otherwise waste material. The formation of nanocarbons was investigated at different KOH concentration, activation temperature and carbonization time. Fourier Transform Infrared (FT-IR) spectroscopy, X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Brunauer–Emmett–Teller (BET) techniques were used to characterise the nanocarbon material. The results showed that nanocarbons with high specific surface areas in excess of 950 m 2 /g and nanostructured morphologies characterized by pore width averages ranging from 3.33–8.87 nm, pore diameter 10.59–45.30 nm and particle size 25.34–54.88 nm could be formed. Optimum nanocarbon production was achieved when the precursor was activated using 10% KOH and carbonized at a temperature of 400 ℃ for 4 h. Characteristic FT-IR absorption bands were observed in all carbonized samples. SEM images revealed a dense irregular material with cavities and protuberances. XRD patterns showed that crystallinity of the nanocarbons decreased with increase in carbonization time. The properties reported for the nanocarbons are ideal for adsoption of analytes from complex matrices, hence presenting N. tabacum as a promising low-cost and green alternative precursor for nanocarbon production targeting analytical fields such as solid-phase extraction and solid phase microextraction. The produced nanocarbons appear to be carbon nanoparticles comprising nearly spherical particles.

Quantitative Characterization of Activated Carbon from Cow, Donkey, Chicken and Horse Bones from Ezzangbo in Ebonyi State, Nigeria

Animal bones have been used to produce carbon char for quality assessment of activated carbon over non activated carbon (used as sample control) as influenced by method of activations (acid and heat). In this study samples analyzed were carbonized in a closed crucible at 400°C and ground into powder after cooling. 200g of each of the crushed samples was activated using 250ml of 2 M Hydrochloric acid for one hour at 80°C and another 200g was activated by thermal method at 120°C for 3 hours. To obtain the optimum weight lost of the carbons, the carbonization period was varied from 0.5-3hours. From the result, increase in carbonization time caused an appreciable increase in the percentage weight loss, this reached a maximum value at a carbonization time of 2.5 hours for both carbon samples at a corresponding percentage weight lost of 63%, 58%, 54% and 62% for cow, donkey, chicken and horse bones respectively. The percentage of carbon yield of cow, donkey, chicken and horse bones upon acid activation are in increasing order of cow (48.92%) > horse (48.64%) > donkey (46.34%) > chicken (44.80%) bones and horse (37.03%) > cow (36.21) > donkey (34.96%) > chicken (30.18%) upon heat activation. Among the bone samples, chicken bone has the least ash content of 12.84%, 11.05% and 15.84% for acid, heat and non-activated samples respectively. The difference in bulk densities of acid activated and heat activated carbons are infinitesimal. The order of increasing bulk densities is cow (0.80g/m3) > donkey (0.78g/m3) = horse (0.78g/m3) > chicken (0.49g/m3). The heat activated carbons shows higher percentage of hardness than the acid activated and non-activated carbons. This study indicated that activated carbons from Cow, Donkey, Chicken and Horse are effective as adsorbents with those obtained from chicken having better features of adsorbents.

Optimization of Conditions for the Preparation of Activated Carbon from Lapsi (Choerospondias axillaris) Seed Stone Using ZnCl<sub>2</sub>

Activated carbon was prepared from Lapsi (Choerospondias axillaries ) seed stone by chemical activation method using ZnCl2. The effect of experimental variables; ZnCl2 ratio, temperature and carbonization time on the quality of the activated carbon were systematically invested by determining the carbon yield, iodine number, methylene blue number, surface area and pore volume. Lapsi seed stone powder (LSP) of particle size < 300 μm was used to prepare activated carbon under N2 atmosphere. An increase in ZnCl2 ratio in general increased the iodine number and methylene blue number, but on increasing zinc chloride above 50 percentages, iodine and methylene blue number increased only marginally. An increase in carbonization temperature increases the iodine number, methylene blue number, and surface area and pore volume. Increase in carbonization time from 3 hour to 4 hour increases iodine number and methylene blue number and thereafter the increase in iodine number and methylene blue number is gradual. Regarding the carbon yield, it decreases with the ZnCl2 ratio above 50 percent, and the yield also decreases with increase in temperature and carbonization time. Therefore the optimum conditions for the preparation of activated carbon from Lapsi seed stone using ZnCl2 as follows: carbonization temperature of 400°C, zinc chloride ratio as LSP:ZnCl2 equals 1:1, and carbonization time of 4 hour. This resulted an activated carbon with 791 iodine number, 364 methylene blue number, 1167 surface area and 0.65 pore volume.Journal of the Institute of Engineering, 2015, 11(1): 128-139

Synthesis and characterizations of nanoporous carbon derived from Lapsi (Choerospondias axillaris) seed: Effect of carbonization conditions

We report a facile synthesis of nanoporous activated carbons (NACs) derived from Lapsi (Choerospondias axillaris) seed powder (LSP). LSP and sodium hydroxide (NaOH) are mixed in 1:1 ratio by wt. and carbonized at 400°C for different time (3, 4, and 5h) and at different temperature (400, 500, 600, and 700°C) for 3h under a constant flow of ultrapure nitrogen gas. The effect of the conditions during the preparation on the structures and properties of NACs is investigated carefully. Fourier transform infrared spectroscopy (FT-IR) show the presence of several functional groups (e.g., hydroxyl, carbonyl, and carboxyl groups) on the carbon surface. Irrespective of the carbonization conditions, both D and G bands are clearly observed in Raman scattering spectra. It is found that the increase in carbonization time significantly increases the G/D bands ratio, indicating an enhancement in the graphitic character. The NACs prepared by carbonization at 400°C for 3h have the highest surface area (over 1000m2g−1) and show high adsorption efficiency in removing methylene blue (MB) from aqueous solution (around 200mgg−1).

Soy hull carbon as adsorbents of crude soy oil components: Effect of carbonization time

AbstractStudies were conducted to evaluate the performance of soy hull carbon adsorbents as affected by carbonization time. Carbonization was done by heating soy hulls to 400°C for up to 30 min. Increased carbonization time resulted in elevated surface pH and titratable alkalinity. The effectiveness of adsorbents in binding minor soy oil components was studied. Free fatty acids content was decreased 70% with adsorbents carbonized for 30 min. Peroxides were adsorbed, but increasing carbonization time did not alter absorption by carbons. A similar trend was observed with the adsorption of total phospholipids. The residual lutein content of crude soy oil was not affected by the adsorbents. X‐ray diffraction studies showed that carbonization at 400°C converted the polysaccharide‐based structure of soy hull to an amorphous, highly disorganized, random structure. Increase in carbonization time resulted in broadening of the diffraction pattern between 5 and 25° 2ϑ. Infrared spectra of soy carbon samples revealed presence of asymmetric C‐H stretch, symmetric C‐H bends, and C=O groups. The intensities of these spectra decreased with time of carbonization.

Growth of β-SiC film on Si substrate by surface reaction using hydrocarbon gas and Si molecular beams in ultrahigh vacuum

The growth of β-SiC on Si(111) substrate was performed with a two-step growth method in a molecular-beam epitaxy (MBE) system using a C2H2 gas source and a Si solid source: an initial optimal carbonization process followed by MBE. The properties of SiC film were analyzed with in situ Auger electron spectroscopy, reflection high-energy electron diffraction, and x-ray photoemission spectroscopy and with ex situ Fourier transform infrared and ellipsometry. In the surface carbonization, the reacted surface showed a change from the β-SiC structure to a carbon-absorbed SiC structure with the increase in carbonization time. A carbonization time of 10 min, a substrate temperature of 875 °C, and a growth pressure of 1.6×10−6 Torr were found to be optimal for the surface carbonization. The growth of SiC was conducted at 900 °C for 30 min with a 0.8 Å/s Si beam flux and a 1.6×10−6 Torr of growth pressure and the films obtained showed single crystalline β-SiC. However, thick films obtained with high growth rates showed polycrystalline structures.