Carbon Pellets Research Articles

Chemical Safety Assessment of Pitch-Based Activated Carbon Pellets via Highly Toxic Gas Adsorption Properties

This study focuses on the preparation of activated carbon using a petroleum-residue-based pitch, as well as the HCl gas adsorption properties of the resulting activated carbon pellets relative to their specific surface area and pore structure. Activated carbon was prepared under various oxidation and chemical activation conditions using pitch with a softening point of 220 °C. The activated carbon was mixed with distilled water, an acrylic binder, and carboxymethyl cellulose in a specific ratio to form pellets. These pellets were then dried in an oven at 80 °C. Scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Brunauer–Emmett–Teller analyses were performed to evaluate the surface structure and specific surface area of the finalized pellets. HCl gas was adsorbed at a concentration of 50 ppm while examining the adsorption characteristics relative to the pore structure and specific surface area.

Enhanced mechanical stability with hierarchical porosity of activated carbon pellets realized through the use of combined polymer binders

Enhanced mechanical stability with hierarchical porosity of activated carbon pellets realized through the use of combined polymer binders

A comprehensive kinetic study on low-GHG hydrogen production from microwave-driven methane pyrolysis

The present study focuses on the cogeneration of hydrogen (H2) and solid carbon from microwave-driven methane pyrolysis in a fluidized bed of carbon pellets. Numerical simulations using a coupled gas-solid chemistry approach reveal that introducing microwave thermal effects improves methane conversion rate, H2 selectivity, and carbon deposition rate. The chemical pathways analysis divulges that once the leading reaction for decomposing CH4 into H2, i.e., CH4+H ↔ CH3+H2, is completed, the C2H2 deposition mechanism onto the carbon pellets is the dominant pathway for the solid carbon production, indicating almost no carbon black (i.e., nanoparticles) formation. Carbon pellets provide abundant surface area for the conversion of C2H2 to H2, enhancing H2 selectivity in the resulting products. More importantly, the importance of more complex molecules, such as polycyclic aromatic hydrocarbons, greatly diminishes when using carbon pellets in the pyrolysis process, implying that smaller kinetic mechanisms are equally effective and desirable.

Preparation and characterization of pitch-derived activated carbon pellet for butane adsorption

Preparation and characterization of pitch-derived activated carbon pellet for butane adsorption

Organic acid-assisted organosolv fractionation of sawdust and using the fractionated lignin to prepare activated carbon pellets for high-temperature applications

In present, activated carbon (AC) pellets that are commonly prepared by petroleum-based binders have been used to control NOx, SOx, and volatile organic compounds (VOCs) emissions in the iron/steel industry. However, the use of petroleum-based binders leads to great challenges toward sustainability and environment. Alternatively, lignin as a natural bio-binder derived from biomass and organic waste can act as a potential additive for preparing AC pellets. Therefore, in this study, pinewood sawdust was initially fractionated into crude cellulose and lignin by organosolv fractionation method at 90–120 °C for 180 min in an acetic acid/formic acid/water mixed solvent of 3/5/2, 3/6/1, and 5/4/1, vol%/vol%/vol%. Afterward, the fractionated crude lignin was used as bio-additive to substitute 50 wt% of petroleum-derived phenol to synthesize phenol-formaldehyde resole resins (PLPF) and compared with those prepared using 100% petroleum-derived phenol resole resins (PF). PLPF and PF resins were further fabricated to AC pellets by thermal treatment/curing at 150 °C and different loadings of resins (i.e., 10–50 wt%), followed by carbonization at 400 and 700 °C. In the fractionation, it was found that temperature played a role in determining the yield and purity of crude cellulose and lignin, while the effect of solvent composition was insignificant. PLPF resins (loading of 50 wt%)-based AC pellets obtained from thermal treatment at 150 °C followed by carbonization at 400 °C showed a relatively higher compressive strength, which meets the national standard and could ensure their uses as an emission control method in the iron/steel industry. Overall, it can be concluded that lignin-derived from woody biomass by organosolv fractionation in acetic acid/formic acid/water mixture is an alternative bio-binder to prepare AC pellets for emission control at high temperatures.

Experimental investigation of micro-ECM on MONEL 400 alloy using particles mixed electrolyte

The machining of extremely hard material in conventional machining requires high energy. Therefore stress-free, burr-free, and high-accuracy machining technique like Electro Chemical Micro Machining (ECMM) with extra features is recommended. To improve efficiency, various electrolytes such as Magnet Associated Electrolytes (MGAE), Metal Particle Mixed Electrolytes (MPME), and Carbon Pellets Mixed Electrolytes (CPME) are employed. The micro-holes were drilled over the work material MONEL 400 alloy. The parameters for the studies are electrolyte type, concentration (g/l), machining voltage (V), and duty cycle (%). The responses of ECMM are estimated through material removal rate (MRR) in ?m/sec and overcut in ?m. The results are optimized using Multi-objective optimization based on ratio analysis (MOORA) and VlseKriterijumska Optimizacija I Kompromisno Resenje (VIKOR). Both techniques produce the same optimal parameter, 18th experiment CPME, 50% duty cycle, 11 V machining voltage, and 28 g/l electrolyte concentration. It is the best optimal parameter solution for machining. According to the ANOVA table of both, the type of electrolyte plays a 62.6% and 60.37% contribution, respectively, to machining performance. Furthermore, the scanning electron microscope (SEM) image analysis perused on the micro holes to extend the effect of different electrolytes on machining surfaces.

Porous carbon pellets for physical adsorption of CO2: size and shape effect

The use of sorbents for physical adsorption of CO2 represents a promising and increasingly vital approach in the effort to reduce energy consumption per ton of CO2 capture and mitigate CO2 emissions.

The Effect of Activated Carbon Pellet on Hydrothermal Decarboxylation of Palm Olein into Renewable Diesel

The Effect of Activated Carbon Pellet on Hydrothermal Decarboxylation of Palm Olein into Renewable Diesel

Fixed-bed biofilter for polluted surface water treatment using chitosan impregnated-coconut husk biochar

Pelletizing biochar enables its use as a biofilter medium for polluted canal water treatment. Coconut husk biochar pellets and their modification with chitosan (CHC) were compared with conventional activated carbon pellets and gravel. The biofilter columns with these media were operated with a hydraulic loading rate of 0.1 m3/m2∙h. CHC showed the highest potential to reduce phosphate and nitrogen, via the adsorption process in the first week of filtration and later enhanced by biodegradation, to achieve removal efficiencies of 61.70 and 54.37% for these two key nutrients, respectively, over five weeks of biofilter operation. The predominant bacteria in the biofilter communities were characterized at the end of the experiments by next generation sequencing and quantitative polymerase chain reaction analysis. The biofilter communities included ammonium oxidizing, nitrite oxidizing, denitrifying, polyphosphate accumulating and denitrifying phosphate-accumulating bacteria that benefit nutrient removal. The CHC biofilter also effectively removed micropollutants, including pharmaceuticals.

Sustainable synthesis of green adsorbent pellets with optimal attributes of capacity, strength, and cost from powdered activated carbon

Powdered Activated Carbon (PAC) particles packed in tall industrial fixed bed columns pose practical problems such as high column pressure drop and solid losses during handling. Hence, the PACs are shaped in form of pellets using a suitable combination of binders. PAC made from coconut shells is mixed with bentonite and carboxy methyl cellulose (CMC) to form pellets. The problem is to identify an optimal blend of binders and PAC that satisfies multiple objectives viz. mechanical strength, gas adsorption capacity and cost. The first two objectives were quantified in terms ball pan hardness (BPH), and carbon tetra chloride activity test (CTC). Since CTC is a banned chemical reagent, its equivalence viz. n-butane adsorption test was performed. An experimental mixture design methodology is presented where these multiple objectives were described through correlations that were optimized either singly or together. Different proportions of binders and PAC were suggested for the different objectives. Hence, a benefit to cost ratio (BCR) response was further defined to identify the final proportion of binders and PAC in the pelletized adsorbent that was economical and did not compromise on its hardness and adsorption capacity. This strategy contributed to synthesis of carbon pellets that simultaneously satisfied structure, performance, and cost requirements. The final pellet with maximum BCR exhibited a BPH of 98.55%, CTC of 67.65% and a scaled cost of 96.79.

Modelling the reduction of quartz in a quartz–carbon pellet

Traditional refining of silicon generates carbon dioxide emissions that are released into the atmosphere. An alternative process under experimental exploration uses quartz particles coated in a layer of porous carbon as the raw material, instead of lumps of quartz and carbon. The quartz–carbon pellets are processed at a lower temperature than in an industrial furnace, and hence, different chemical reactions are dominant, reducing the greenhouse gas emissions. The quartz core shrinks as it is consumed, and the carbon is converted to silicon carbide, which can subsequently be processed into silicon. We develop a model for chemical and transfer processes within a single quartz–carbon pellet. We derive governing equations for the concentration of silicon monoxide, carbon monoxide, and carbon dioxide, and conservation equations on the moving quartz interface. Furthermore, we then focus on a reduced model in an industrially relevant distinguished limit, and solve numerically the resulting leading-order system. We show examples of reaction-limited behaviour as well as diffusion-limited behaviour. Both regimes are physically admissible due to the large potential range of the parameters. Finally, we sweep through the parameter space, and characterize the dynamics based on the utilization of the carbon and the silicon yield. We find that the diffusion-limited regime is best for carbon utilization and silicon yield, as the silicon monoxide reacts with the carbon before it is transported out of the pellet.

Dissolving Activated Carbon Pellets for Ibuprofen Removal at Point-of-Entry

The increased usage of pharmaceuticals coupled with the desire for greywater reuse to reduce the freshwater demand for potable water requires a user-friendly engineered solution. Activated carbon is a proven technology that is typically used for organic pollutant removal at water treatment plants. Lignite, coconut, and a blend of activated carbon powders were used to develop rapid-dissolving pellets with an inorganic binder. Ibuprofen was the model compound chosen for pharmaceutical adsorption in deionized water and synthetic hydrolyzed and synthetic fresh urine at rapid contact times (0.5 to 30 min) and using various pellet dosages (0.5 to 10 g/L). A cost analysis was performed to determine the feasibility of the engineered solution. With an increase in contact time, the coconut pellets outperformed both the blend and lignite pellets in deionized water at a set pellet dosage. The lignite pellets were the most cost-effective with rapid adsorption in fresh urine and a capacity of 0.089 g ibuprofen/g pellet. Additional optimization parameters include pellet dissolvability, pellet dosage in relation to different pharmaceuticals, and the impact of activated carbon on the household sewage system, and each of these are necessary to determine application feasibility.

Activated Carbon and Clay Pellets Coated with Hydroxyapatite for Heavy Metal Removal: Characterization, Adsorption, and Regeneration.

In the present work, activated-carbon-containing pellets were preparedby direct chemical activation of sawdust, using clays as a binder. The obtained pellets (ACC) were coated with hydroxyapatite (HAp) nanoparticles (ACC-HAp) to improve adsorption towards Pb(II), Cu(II), Zn(II), and Ni(II). The pellets were characterized by scanning electron microscopy (SEM), by Fourier transform infrared spectroscopy (FTIR), and with a gas sorptometer. The effect of pH, contact time, and initial concentration on adsorption performance was investigated. Additionally, desorption studies were performed, and the regeneration influence on compressive strength and repeated Pb(II) adsorption was investigated. The results showed that, after coating ACC pellets with HAp nanoparticles, the adsorption capacity increased for all applied heavy metal ions. Pb(II) was adsorbed the most, and the best results were achieved at pH 6. The adsorption process followed the pseudo-second-order kinetic model. The adsorption isotherm of Pb(II) is better fitted to the Langmuir model, showing the maximum adsorption capacity of 56 and 47 mg/g by ACC-HAp and ACC pellets, respectively. The desorption efficiency of Pb(II)-loaded ACC-HAp pellets increased by lowering the pH of the acid, resulting in the dissolution of the HAp coating. The best desorption results were achieved with HCl at pH 1 and 1.5. Therefore, the regeneration procedure consisted of desorption, rinsing with distilled water, and re-coating with HAp nanoparticles. After the regeneration process, the Pb(II) adsorption was not affected. However, the desorption stage within the regeneration process decreased the compressive strength of the pellets.

Effects of Using Indaziflam and Activated Carbon Seed Technology in Efforts to Increase Perennials in Ventenata dubia–Invaded Rangelands

Reestablishing perennial vegetation dominance in ventenata (Ventenata dubia)– and other annual grass–invaded rangelands is critical to restoring ecological function and increasing ecosystem goods and services. Recovery of perennial dominance in ventenata-invaded rangelands is challenging and constrained by a lack of established best management practices; however, preemergent herbicides can, at least temporarily, reduce ventenata. Indaziflam is a preemergent herbicide that has longer soil activity than other commonly used preemergent herbicides that needs evaluated to determine if it offers multiple-year control of ventenata and to determine its effects on residual perennial vegetation. Some ventenata-invaded rangelands may not have enough residual vegetation to occupy the site after ventenata control, but longer soil activity with indaziflam likely limits establishment of seeded species. However, incorporating seeds in activated carbon pellets, which can limit herbicide damage, may be a strategy for establishing perennial vegetations simultaneously with indaziflam application. We evaluated 1) applying indaziflam to control ventenata and 2) broadcast-seeding perennial grass seed incorporated in activated carbon pellets with a simultaneous indaziflam application at two sites for 3 yr post treatment. Indaziflam controlled ventenata for the 3 yr sampled. Perennial grasses increased with indaziflam at the site that had more residual perennial grasses before treatment. At the other site, perennial forbs increased with indaziflam. Indaziflam offers multiple-year control of ventenata; however, plant community response depends on composition before treatment. Seeding perennial grass seeds incorporated in activated carbon pellets while indaziflam controlled ventenata did not increase perennial grass abundance. Though this was likely associated with low establishment due to below-average precipitation post seeding and because broadcast seeding is often an ineffective seeding method, we cannot rule out nontarget herbicide damage. Further evaluations of activated carbon technologies used in conjunction with indaziflam are needed to determine if this can be an effective management strategy.

The Effect of Physicochemical Properties and Surface Chemistry on CO2 Adsorption Capacity of Potassium Acetate-Treated Carbon Pellets

The aim of this study is to prepare a carbon pellet using low-cost material and a green process with excellent surface properties for carbon dioxide (CO2) capture application. To enhance the surface properties of the carbon pellet, a chemical activation method was introduced by modifying the pellet with potassium acetate. Then, the carbon pellet was tested in a packed-bed adsorption column to evaluate their performance for breakthrough time and CO2 adsorption. The effect of the physicochemical and surface chemistry of the carbon pellet on CO2 adsorption was also studied. The SEM image showed remarkable changes in the surface morphology of the carbon pellet after modification with potassium acetate. In addition, the presence of oxygen-containing functional groups such as hydroxyl and carbonyl groups in the modified carbon pellet could effectively enhance the CO2 adsorption capacity. Thus, it is proven that the carbon pellet modified with potassium acetate is suitable for CO2 adsorption. The results revealed that the CAC-PA 2M obtained the longest breakthrough time (19.4 min), higher adsorption capacity (0.685 mmol/g), and good recyclability (the regenerated sample can be reused for more than five cycles). The comprehensive characterization study and CO2 adsorption experimental data on new carbon pellets can provide a direction for new researchers that are venturing into the CO2 capture field.

Activated carbon supported nickel catalyst for selective CO2 hydrogenation to synthetic methane under contactless induction heating

The use of CO2 methanation in the power-to-gas (PtG) technology chains has received increasing attention in recent years for clean energy and sustainable development. In this work, macroscopic mesoporous nickel catalyst was prepared and evaluated for selective CO2 hydrogenation to CH4 using commercial activated carbon (AC) pellets. Catalyst samples were fully characterized by liquid N2 adsorption-desorption, X-ray diffraction (XRD), H2 temperature-programmed reduction (H2-TPR), scanning and transmission electron microscopy (SEM/TEM). Catalytic performances were investigated under various reaction conditions with both direct induction heating (IH) and conventional indirect Joule heating (JH) modes. Results indicated that by simple thermal treatment, the surface and textural properties of the macroscopic carbon support could be greatly modified by improving the dispersion of metal sites and thus the catalytic performance. The advantages of IH combined with the inherent high thermal and electrical conductivity of the prepared materials could effectively avoid the temperature runaway and enhance the CO2 activation at relatively low reaction temperature. By comparison to the classical indirect JH mode, the resulting macroscopic nickel catalysts showed improving catalytic performances for CO2 methanation under IH mode. The efficient heat management under direct IH mode also prevented coke formation on the catalyst surface which contributes to its high stability as a function of time-on-stream.

On the Formation of a Plasma Cloud at the Ablation of a Pellet in a High-Temperature Magnetized Toroidal Plasma

The investigation of cold secondary plasma clouds near pellets ablating in the hot plasma of magnetic confinement devices (tokamaks and stellarators) provides valuable information on the physical characteristics of a pellet cloud. In this work, the characteristic sizes of emitting clouds around fusible polystyrene pellets and refractory carbon pellets have been analyzed. The calculation of the ionization length of C+ ions in both carbon and hydrocarbon clouds has shown that the contribution of only hot electrons is insufficient to ensure the experimentally observed decay lengths of the CII line intensity. Taking into account the strong shielding of the electron flux of the background plasma in the hydrocarbon pellet cloud, the ionization of C+ ions in this cloud is determined predominantly by electrons of the cold plasma of the cloud. Shielding near a refractory carbon pellet is weak because its ablation rate is lower. The contributions from hot electrons of the surrounding plasma and cold electrons of the pellet cloud to the ionization of C+ ions are comparable in the case of carbon pellets.

Crystallites Dimensions and Electrical Conductivity of Solid Carbon Pellets (SCPs) from Date Palm Leaves (Phoenix dactylifera L.)

Solid carbon pellets (SCPs) were prepared from self-adhesive properties of date palm leaves (Phoenix dactylifera L.), primary pre-carbonized at low temperature, milled to fine grain, powdered, and pelletized as a grain pellet by applying of (5-21) metric tons of compression load, to carbonization at 1000 ºC. The SCPs produced were analyzed in terms of the volume shrinkage, carbon yield, crystallites dimensions and electrical conductivity of the solid carbon pellets as a function of compression load. The values of the electrical conductivity were further analyzed in terms of percolation theory to estimate the critical density of the SCPs produced. The results show that the volume shrinkage and carbon yield after carbonization were in a range of 54.0-64.8% and 26.98-32.4%, respectively, indicating that the body is physically shrinking to maintain its structural integrity. X-ray diffraction intensity shows that the structures of the SCPs are non-graphitic, and their crystallite dimensions are improved by increasing the compressive load. The d002, Lc and La data were found to obey the linear relation of d002 versus 1/ Lc and 1/ La, as Lc and La approach infinity. The electrical conductivity was varied with the compression load and 19 metric tons is a higher value than the others. The critical density of the SCP obtained from the percolation theory was 0.025 g/cm3.

Catalytic Upgrading of Plastic Waste of Electric and Electronic Equipment (WEEE) Pyrolysis Vapors over Si–Al Ash Pellets in a Two-Stage Reactor

This study investigated thermal cracking and catalytic upgrading of waste from electric and electronic equipment (WEEE) plastics on a semi-batch reactor coupled to a heated catalyst fixed bed (2-stage vapor cracking). The catalyst used is a Si–Al ash obtained from commercial activated carbon pellets treated with concentrated NaOH solution and calcination. The purpose of the study was to characterize the waste stream through its thermogravimetry analysis and pyrolysis products, study the effect of temperature (350–500 °C) and catalyst quantity (0.0–7.5 %.wt) on yields of reaction products, physical chemical properties, and chemical composition of bio-oil in order to understand and evaluate production of fuels and chemical feedstock by recycling of WEEE plastic through catalytic upgrading. Time-fractioned samples were taken in determined reaction times (15, 30, 45, and 60 min) to study the evolution of cracking reactions during experiment runs through changes to chemical composition (GC/MS). A comparison with other previous work is also presented to show similarities between different feedstocks using the same thermal unit. The results indicate composition of brominated acrylonitrile-butadiene-styrene (ABS), polycarbonate (PC), and high impact polystyrene (HIPS) for the WEEE plastic. The temperature of 350 °C produced better results when considering acid value but presented lower bio-oil yields (38%) and high gas yields (42%). Catalytic upgrading experiments revealed the increased presence of polycyclic aromatic hydrocarbons (PAH) with an increase in viscosity of bio-oil, increase in char yield (from 11% to 24%), and decrease in gas yields (15% to 5%). Chemical composition showed presence of aromatic hydrocarbons such as styrene, methyl-styrene, and diphenyl-propane and nitrogenated compounds such as benzene-butane-nitrile, phenolic compounds, PAHs, and brominated compounds. WEEE plastic pyrolysis is a challenging subject due to contaminant presence and varying composition, and chemical composition evaluation according to reaction time provides interesting insights into the evolution of semi-batch pyrolysis/catalytic upgrading experiments. Standardization and reproducibility of the tool should be conducted to continue the evaluation of pyrolysis and catalytic upgrading of a wide range of feedstocks.

Effect of binder ratio on the physical properties of porous carbon pellet for CO2 capture

The purpose of this work was to investigate the effect of binder ratio on the physical properties of carbon-based pellets in capturing CO2. The influence of the binder materials was also examined to compare the pellet quality. To make good-quality carbon pellets, tapioca starch (TS) and xanthan gum (XG) were used as organic binders and mixed with activated carbon to form pellets. The physical properties of the carbon pellets were analyzed using different analytical methods: Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDX), Thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR). In addition, the CO2 adsorption performance of the carbon pellets was investigated by evaluating their adsorption capacity and CO2 breakthrough characteristics. The results revealed no significant changes to the pore development of the carbon pellets after the CO2 adsorption. However, the EDX results for the carbon pellets using the starch binder showed an increase in the oxygen content after the CO2 adsorption. With the addition of water and the binder, both types of carbon pellets (TS-AC and XG-AC) still produced high carbon content. Interestingly, the carbon pellets using the low-cost binder (tapioca starch) shows high performance than xanthan gum binder due to has numerous functional groups, longer breakthrough time and high CO2 adsorption capacity. The TS-AC carbon pellets exhibited a remarkably high breakthrough time and CO2 adsorption capacity of 16.2 min and 21.84 mg/g at 25 ˚C.