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Chemically activated carbons derived from cashew nut shells as potential electrode materials for electrochemical supercapacitors
(2025-06-01)
Chaiammart, Nattapat
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Vignesh, Veeramuthu
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Thu, Myo Myo
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Eiad-ua, Apiluck
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Maiyalagan, Thandavarayan
Supercapacitors are widely recognized as energy storage solutions due to their high power densities and long cycle lives. Furthermore, there is growing scientific and technological interest in converting biomass waste into carbon materials for manufacturing supercapacitor electrodes. In addition to their abundance and cost-effectiveness, the appeal of carbons derived from biomass lies in their tunable porosity, which enables the rational design of carbon materials to achieve the desired performance of supercapacitors. Here, we present the synthesis of activated carbons from cashew nut shells via potassium hydroxide (KOH) activation at different temperatures (650, 750, and 850 °C). The resulting materials exhibited amorphous and predominant microporous structures. Increasing the activation temperature led to a rise in specific surface area from 1534 to 2034 m2 g−1 and an increased proportion of mesopores. The electrochemical properties of these activated carbons for supercapacitor applications were investigated by cyclic voltammetry, galvanostatic charge–discharge, and impedance spectroscopic techniques in a 1 M sodium sulfate (Na<inf>2</inf>SO<inf>4</inf>) electrolyte. Using a three-electrode system, the activated carbons treated at 750 °C exhibited a maximum specific capacitance of 106 F g−1 at a current density of 0.5 A g−1 with a good rate capability; they retained 75 % at 10 A g−1 over a 1.0 V voltage window. Furthermore, a symmetric supercapacitor coin-cell, fabricated with activated carbons treated at 750 °C as the positive and negative electrodes, demonstrated an energy density of 2.43 Wh kg−1 at a power density of 1002 W kg−1. The cell exhibited 87 % capacitance retention at 1.0 A g−1 after 10,000 cycles. This work showcases the efficient and sustainable utilization of cashew nut shells as a carbon source for supercapacitor applications and highlights their value in a circular economy.
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Enhanced biodiesel purification using coffee husk bioadsorbents: The role of pyrolysis temperature, KOH activation, and adsorption efficiency
(2025-05-01)
Chungcharoen, Thatchapol
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Limmun, Warunee
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Srisang, Siriwan
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Phetpan, Kittisak
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Ruttanadech, Nuttapong
This study evaluates the performance of bioadsorbents derived from coffee husk pyrolyzed at temperatures of 600, 700, and 800 °C (CH600, CH700, and CH800), along with activated CH700 (ACH700), in biodiesel purification. The results indicate that CH700 significantly enhances biodiesel purity, with optimal purification conditions achieved at a dosage of 2 wt% CH700, a stirring rate of 400 rpm, and a contact time of 45 min. CH700 demonstrated modest performance, achieving approximately 20 % removal of methanol and water. However, after activation with potassium hydroxide (KOH), ACH700 demonstrated improved efficiency, achieving 96.92 % methanol removal and 39.46 % water removal. ACH700 also refined biodiesel quality to meet EN14214 standards and maintained a higher biodiesel yield compared to other adsorbents. The bioadsorption process is influenced by the chemical interactions between the surface functional groups of the bioadsorbent and the contaminants, which is further enhanced by the optimized pore structure of ACH700. The use of ACH700 represents a novel and highly effective approach to biodiesel purification, combining both technical efficiency and economic feasibility. Furthermore, the valorization of agricultural waste adds significant environmental benefits, reinforcing the potential of ACH700 for large-scale biodiesel production.
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Synthesis of nanoporous carbon from brewer waste by hydrothermal carbonization assisted chemical activation for carbamazepine adsorption
(2024-06-01)
Apinyakul, Naruemon
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Chanpee, Sirayu
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Kaewtrakulchai, Napat
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Khemasiri, Narathon
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Eiad-ua, Apiluck
Nanoporous carbon (NPC) has gained significant attention in wastewater treatment due to its effectiveness. The adsorption process, known for its simplicity, stability, and cost-effectiveness, is widely recognized as an efficient method for removing carbamazepine (CBZ) residues accumulate in the environment. However, the application of NPC is often hindered by challenges in the regeneration process after use, as well as issues related to large surface area, pore size, and functional groups. Fortunately, the samples in this study not only maintained their adsorption efficiency but also demonstrated the ability to be regenerated multiple times. Herein brewery waste was subjected to hydrothermal treatment at 200 °C for 1 h and followed by KOH and NaCl activation with different KOH:NaCl (w/w) ratios of 5:0, 4:1, 3:2, 1:1, 2:3, 1:4, and 0:5 to optimize the properties of malt husk derived nanoporous carbon (NPC). The optimal condition KOH:NaCl ratio of 1:1 had a maximum specific surface area of 906 m2/g with a total pore volume of 0.252 cm3/g. According to the adsorption test, the CBZ adsorption isotherm was well-fitted to the Langmuir model (R2 = 0.976) kinetic data were consistent with the pseudo-second-order model (R2 = 0.995). This suggests that the adsorption mechanism involves monolayer adsorption and chemisorption interaction. The Gibbs free energy and enthalpy of CBZ adsorption by NPC were found to be spontaneous and endothermic. The regeneration test revealed a 95.35% decrease in the adsorption capacity of NPC after 5 repeated cycles. Consequently, the study suggests a potential application of nanoporous carbon from MH as an alternative adsorbent for removing carbamazepine in wastewater.
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Bimetallic PdNi catalyst on cattail Leaves-Derived nanoporous carbon support for synthesis of partially hydrogenated fatty acid methyl ester (H-FAME)
(2024-06-01)
Longprang, Tripob
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Kaewtrakulchai, Napat
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Kiatkittipong, Worapon
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Srifa, Atthapon
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Chollacoop, Nuwong
Cattail leaves (CL) have been used as a carbon source to synthesize nanoporous carbon (NPC) support with high surface area (S<inf>BET</inf> = 2002.12 m2g−1) via hydrothermal carbonization and potassium hydroxide (KOH) activation. The studied catalysts, including monometallic Pd/NPC and Ni/NPC, and bimetallic PdNi/NPC, were synthesized and characterized by using several techniques (e.g., scanning electron microscopy, transmission electron microscopy, nitrogen sorption, Fourier transform infrared spectroscopy, thermogravimetric analysis, and X-ray diffraction). Their catalytic activity toward partial hydrogenation of palm biodiesel to H-FAME was tested, and the liquid product composition, cloud point, and oxidation stability were determined. The studied catalysts have a high porosity with the S<inf>BET</inf> of approximately 2037.34–2187.96 m2g−1 led to excellent metal dispersion. Although Ni did not show high catalytic activity compared to Pd, Ni incorporated with Pd as PdNi/NPC catalyst significantly increased the cis-C18:1 selectivity and prevented the catalytic deactivation during the partial hydrogenation. The oxidation stability of palm biodiesel feedstock was increased from 13.69 to 17.12 h while the cloud points adversely increased by only 3 degrees from 12 to 15 °C (still lower than 16 °C of the Thai industrial recommendation) with bimetallic PdNi/NPC catalyst. The main benefit of bimetallic PdNi/NPC over monometallic Pd/NPC and Ni/NPC is shown through not only higher C18:2 conversion but also much higher cis-to-trans ratio of C18:1 resulting in higher oxidation stability with acceptable compromise on the cloud point increasing. Consequently, the produced palm H-FAME can be used at a high blend ratio.
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Biomass nanoporous carbon-supported pd catalysts for partial hydrogenation of biodiesel: Effects of surface chemistry on pd particle size and catalytic performance
(2021-06-01)
Udomsap, Parncheewa
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Meesiri, Sirasit
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Chollacoop, Nuwong
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Eiad-Ua, Apiluck
Two types of cattail flower-derived nanoporous carbon (NPC), i.e., NPC activated with KOH and H3PO4, were produced and characterized using several techniques (e.g., Raman spectroscopy, ni-trogen adsorption, and X-ray photoelectron spectroscopy). The influence of the carbon support characteristics on the particle sizes and chemical states of Pd in the synthesized Pd/NPC catalysts, which affect the catalytic activity and product selectivity, was analyzed. The surface chemistry properties of NPC were the main factors influencing the Pd particle size; by contrast, the textural properties did not significantly affect the size of the Pd particles on NPC supports. The use of Pd nanoparticles supported on the rich-functionalized surface carbons obtained by H3PO4 activation led to superior catalytic activity for the polyunsaturated fatty acid methyl ester (poly-FAME) hy-drogenation, which could achieve 90% poly-FAME conversion and 84% selectivity towards mono-unsaturated FAME after a 45-min reaction time. This is due to the small Pd nanoparticle size and the high acidity of the catalysts, which are beneficial for the partial hydrogenation of poly-FAME in biodiesel. Conversely, the Pd nanoparticles supported on the high-surface-area carbon by KOH ac-tivation, with large Pd particle size and low acidity, required a longer reaction time to reach similar conversion and product selectivity levels.
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Optimizing Ammonia Adsorption Using Activated Carbon from Tamarind Pulp
(2021-01-01)
Na-Lampang, Chaiyawat
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Assawasaengrat, Pornsawan
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Phumjan, Lamphung
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Narkrugsa, Woatthichai
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Sriprom, Pongsert
Ammonia is an essential waste from fish and shrimp which has an effect on fish and shrimp transportation for export. This study aimed to remove ammonia by Activated Carbon adsorption. The activated carbon was prepared from Tamarind pulp using different methods (NaOH, H2SO4, the hydrothermal technique and activated by H2SO4 and H2SO4 hydrothermal followed by NaOH). The Activated Carbon was characterized by and Iodine number and Fourier Transform I nfrared Spectroscopy (FT-IR). The results showed that the iodine number of activated carbon prepared by the hydrothermal technique and activated by H2SO4 have the highest surface area and porosity at 537 mg/g, and the functional group on activated carbon surface is carbonyl and sulfonyl group. For ammonia adsorption, the experiments were designed by Box-Behnken design at 3 factors 3 levels including Contact time (10, 95 and 180 min), Dosage of activated carbon (0.5, 1.25 and 2.0 g) and pH of the solution (2, 6.5 and 11). The concentration of ammonia was determined by UV-Visible spectrophotometer. The result showed that the main effects and the interaction effects were found significant effect on ammonia adsorption at confidence level of 95%. However, the interaction effects between contact time and activated carbon dosage was insignificant. Finally, the optimized results suggested that 48.32 ± 0.82% of ammonia concentration could be removed by activated carbon from tamarind pulp under the following conditions: PH of 11, a contact time of 95 min, and activated carbon dosage of 2 g/100 mL. The results are believed to be of importance to fish and shrimp transportation for reduced ammonia and other similar applications.

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