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Valorization of eggshell waste to metal-doped CaO catalysts for producing dimethyl carbonate by transesterification of propylene carbonate with methanol
(2026-05-01)
Seeharaj, Panpailin
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Werupho, Sakila
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Puyamsai, Araya
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Choengchan, Nathawut
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Kim-Lohsoontorn, Pattaraporn
To align with a circular economy, this study aimed to extend the lifecycle of eggshell waste by valorizing it into a catalyst for producing the green chemical dimethyl carbonate (DMC) through the transesterification of propylene carbonate (PC) with methanol. CaO derived from eggshells was modified by doping with 10 mol% of aliovalent metal cations, including Na+, Mg2+, and Ce3+, via a calcination-hydration-dehydration process. The catalyst activity was tested under atmospheric air at 40–70 °C for 1–3 h. Metal-doped CaO possessed better activity than pure CaO, and the performance was ranked in order as CaO < Na–CaO < Ce–CaO < Mg–CaO. At the optimized reaction conditions of 50 °C for 2 h, the Mg–CaO catalyst exhibited the best performance, with 77% PC conversion, 62% DMC selectivity, and 37% DMC yield. This improvement correlated with the high surface-active area and optimum basicity induced by incorporating Mg2+ into the CaO structure and forming MgO–CaO mixed oxide phases. This study demonstrated a greener process for producing DMC under mild conditions using metal-doped CaO catalysts derived from eggshell waste.
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Correlation of urea precipitation temperature with phase formation, morphology, and catalytic activity for CO2 conversion of CeO2
(2025-08-01)
Seeharaj, Panpailin
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Duangtanon, Jenjira
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Sreemueang, Chanakan
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Noppharat, Phetchphalin
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Kulthananat, Tachatad
This study proposes a simple method for tailoring the morphology and activity of cerium oxide (CeO<inf>2</inf>) catalysts in converting carbon dioxide (CO<inf>2</inf>) and methanol to green organic carbonate, dimethyl carbonate (DMC), to utilize and reduce CO<inf>2</inf> emissions. CeO<inf>2</inf> was prepared by urea precipitation at 85, 105, and 125 °C for 2 h, then calcining at 600 °C for 2 h. The phase structure and morphology of CeO<inf>2</inf> correlated with the urea hydrolysis rate. A low degree of supersaturation at 85 °C led to heterogeneous precipitation of cerium oxycarbonate (Ce<inf>2</inf>O(CO<inf>3</inf>)<inf>2</inf>.H<inf>2</inf>O) and CeO<inf>2</inf> with spherical morphology, while a higher degree of supersaturation at 105 °C and 125 °C resulted in homogeneous precipitation of single-phase Ce<inf>2</inf>O(CO<inf>3</inf>)<inf>2</inf>.H<inf>2</inf>O with spindle and elongated octahedral morphology, respectively. The spindle-shaped CeO<inf>2</inf> prepared at 105 °C with a predominant surface (111) facet showed the highest catalytic activity, with a DMC yield of 18.81 mmol.g<inf>cat</inf>−1. The enhanced catalytic efficiency of spindle-shaped CeO<inf>2</inf> was due to the high concentration of surface-active defect sites of exposed cerium cations and oxygen vacancies, which optimized the number of acid–base sites in adsorbing and activating CO<inf>2</inf> and methanol to produce DMC.
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Modification of acid–base properties of metal-doped ZnO catalysts for the transesterification of propylene carbonate with methanol to dimethyl carbonate
(2025-04-01)
Ieamviteevanich, Pimchanok
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Kim-Lohsoontorn, Pattaraporn
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Seeharaj, Panpailin
This study investigated the effect of metal dopants on the surface properties of ZnO-based catalysts for the transesterification of propylene carbonate (PC) with methanol to produce dimethyl carbonate (DMC). A series of metal-doped ZnO nanocatalysts (M-ZnO, where M is Ca2+, Cu2+, Ce3+, La3+, and Y3+ with the mol ratio of Zn2+/Mx+ = 4) were prepared by a simple co-precipitation method followed by calcining in air at 673 K for 5 h. Introducing different metal cations into the ZnO system decreased crystallite size and created surface defects of exposed cations and oxygen vacancies, increasing surface-active acid and basic sites. The catalytic performance for DMC production was ranked as follows: Ca-ZnO < Cu–ZnO < ZnO < Ce-ZnO < Y-ZnO < La-ZnO. La-ZnO showed the highest performance of all catalysts, with 67% PC conversion, 67% DMC selectivity, and 45% DMC yield. The improvement of catalytic activity was correlated with an increase in the concentration of moderate and strong acid–base functionalities on the La-ZnO surfaces for participating in the reaction of PC and methanol to form DMC.
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Platelet Ceria Catalysts from Solution Combustion and Effect of Iron Doping for Synthesis of Dimethyl Carbonate from CO2
(2025-01-01)
Rusta, Nicoletta
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Mameli, Valentina
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Ricci, Pier Carlo
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Porcu, Stefania
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Seeharaj, Panpailin
Solution combustion (SC) remains among the most promising synthetic strategies for the production of crystalline nanopowders from an aqueous medium, due to its easiness, time and cost-effectiveness, scalability and eco-friendliness. In this work, this method was selected to obtain anisometric ceria-based nanoparticles applied as catalysts for the direct synthesis of dimethyl carbonate. The catalytic performances were studied for the ceria and Fe-doped ceria from SC (CeO<inf>2</inf>-SC, Ce<inf>0.9</inf>Fe<inf>0.1</inf>O<inf>2</inf>-SC) in comparison with the ceria nanorods (CeO<inf>2</inf>-HT, Ce<inf>0.9</inf>Fe<inf>0.1</inf>O<inf>2</inf>-HT) obtained by hydrothermal (HT) method, one of the most studied systems in the literature. Indeed, the ceria nanoparticles obtained by SC were found to be highly crystalline, platelet-shaped, arranged in a mosaic-like assembly and with smaller crystallite size (≈6 nm vs. ≈17 nm) and higher surface area (80 m2 g−1 vs. 26 m2 g−1) for the undoped sample with respect to the Fe-doped counterpart. Although all samples exhibit an anisometric morphology that should favor the exposition of specific crystalline planes, HT-samples showed better performances due to higher oxygen vacancies concentration and lower amount of strong basic and acid sites.
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Asymmetric dot-patterned wettable and antibacterial wound dressings from bacterial cellulose–alginate composites coated with stearic acid-modified ZnO/chitosan/AgNPs
(2025-01-01)
Ieamviteevanich, Pimchanok
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Onklam, Panida
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Kampechdee, Wariya
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Churiwan, Achana
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Vittayakorn, Naratip
To improve the wound dressing characteristics of bacterial cellulose-based materials and address the issue of asymmetric wound dressing with one hydrophilic side and another hydrophobic side, this study developed a new concept for the fabrication of an asymmetric wettable and antibacterial wound dressing by selective drop coating of stearic acid-modified ZnO, chitosan, and AgNPs to form a dot pattern on both surfaces of a bacterial cellulose–alginate composite (BA-ZnS/Ch/Ag). The coated surface was hydrophobic, with a WCA of 150° due to the formation of a low surface energy zinc stearate (C<inf>17</inf>H<inf>35</inf>COO)<inf>2</inf>Zn) monolayer on the ZnO particles and a high degree of hierarchical roughness. The asymmetric wettable BA-ZnS/Ch/Ag wound dressing maintained good water absorptivity (swelling rate 417%) and natural breathability (water vapor transmission rate 792 g.m−2 day−1) of the superhydrophilic bacterial cellulose-alginate composite that consisted of dense outer surfaces and porous inner layers and simultaneously possessed the superhydrophobic property of the coating area that can reduce the risk of infection from external fluids and improve the blood repellency and anti-adhesion properties. The BA-ZnS/Ch/Ag wound dressing showed good antibacterial activity against S. aureus and E. coli and non-toxicity to human keratinocyte immortal cells (HaCaT), making it suitable for clinical applications.
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The role of γ-C2H5NO2 as a new transient liquid phase in cold sintering process of BaTiO3 composites
(2024-07-01)
Noisak, Jitrawan
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Ieamviteevanich, Pimchanok
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Charoonsuk, Thitirat
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Pakawanit, Phakkhananan
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Pinpru, Nattapong
Dielectric materials, such as barium titanate (BT)-based materials, have excellent dielectric properties but require high temperatures (above 1300 °C) for ceramic fabrication, leading to high costs and energy loss. The cold sintering process (CSP) offers a solution to these issues and is gaining worldwide attention as an innovative fabrication route. In this work, we proposed an alternative organic ferroelectric phase, gamma-glycine (γ-GC), which acts as a transient liquid phase to fabricate high-density composites with barium titanate (BT) at low temperatures through CSP. Our findings show that the density of 15γ-GC/85BT reached 96.7%±1.6% when it was sintered at 120 °C for 6 h under 10 MPa uniaxial pressure. Scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) mappings of the composite suggested that γ-GC completely underwent the precipitation–dissolution process and, therefore, filled between BT particles. Moreover, X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) confirmed the preservation of γ-GC without undesired phase transformation. In addition, the ferroelectric and dielectric properties of γ-GC/BT composites have been reported. The high dielectric constant (ε<inf>r</inf>) was 3600, and the low dielectric loss (tanδ) was 1.20 at 200 °C and 100 kHz for the 15γ-GC/85BT composite. The hysteresis loop showed a remanent polarization (P<inf>r</inf>) of 0.55 µC·cm-2 and a coercive field (E<inf>c</inf>) of 7.25 kV·cm-1. Our findings reaffirmed that an organic ferroelectric material (γ-GC) can act as a transient liquid phase in a CSP that can successfully and sustainably fabricate γ-GC/BT composites at low temperatures while delivering outstandingly high performance.
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Superhydrophobic eggshell for fabrication of hydrophobic barrier of paper-based analytical device for colorimetric determination of ammonium ion in water
(2024-05-01)
Thangjitsirisin, Kanyapak
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Seeharaj, Panpailin
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Choengchan, Nathawut
This work demonstrates the first application of the superhydrophobic eggshell as an environmental-friendly material for fabricating the hydrophobic barrier of a paper-based analytical device (PAD). The eggshell surface was modified by mixing the pulverized chicken eggshell biowaste with stearic acid and a polystyrene binder to accomplish superhydrophobicity. The PAD (10 × 10 mm2) is comprised of the circular-shaped hydrophilic reservoir (Ø 5 mm). The liquid barrier was fabricated by painting both the topside and the underside of the filter paper with the dispersed superhydrophobic eggshell solution. The SEM images revealed that the microsized superhydrophobic eggshell particles absorbed onto the porous surface of the cellulose fibril. A coated surface with a water contact angle of 155.39° ± 1.02° (n = 10) on the paper substrate was achieved, and this indicated superhydrophobicity. The eggshell barrier enabled excellent water and chemical resistance. The fabricated PAD was applied for the colorimetric determination of ammonium cations (NH<inf>4</inf>+), based on the modified Berthelot reaction. Samples and chromogenic solutions were aliquoted onto the hydrophilic reservoir, with subsequent capture of the optical image of the stable, green-colored product by a smart phone under a light-controlled studio. The green color intensities were evaluated by ImageJ™ and plotted against the standard NH<inf>4</inf>+ concentrations. A wide linear calibration range 5.0 to 100 mg N/L was achieved with good linearity (r2 > 0.99). The PAD confirmed satisfied analytical recovery (Mean ± SD: 100.6 % ± 0.97, n = 11 samples) and high precision (RSD = 0.85 %: 10-PAD replicate measurements of 1.0 mg N/L). The limit of detection (3 SD of blank/slope) of 1.05 mg N/L was found sensitive enough to monitor the NH<inf>4</inf>+ contents in freshwater. The results, determined by the developed PAD and ion chromatography, showed no significant difference under the statistical paired t-test at 95 % confidence (t<inf>stat</inf> = -1.80, t<inf>cri</inf> = 2.57, n = 6 samples).
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Magnetically separable CeO2/CoFe2O4 heterojunction photocatalysts for dye degradation: characterization and mechanism
(2024-01-01)
Seeharaj, Panpailin
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Pasupong, Patchara
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Choojun, Kittisak
This study developed magnetically separable CeO<inf>2</inf>/CoFe<inf>2</inf>O<inf>4</inf> heterojunction photocatalysts for dye degradation to reduce water pollution. The CeO<inf>2</inf>/CoFe<inf>2</inf>O<inf>4</inf> nanocomposites with different CeO<inf>2</inf> ratios (10, 20, and 30 wt%) were prepared by a precipitation method. The nanocrystalline 20%CeO<inf>2</inf>/CoFe<inf>2</inf>O<inf>4</inf> photocatalyst with a surface area of 117 m2.g−1, E<inf>g</inf> 2.37 eV, and uniform distribution of quasi-spherical CeO<inf>2</inf> minor phase (cubic fluorite structure with particle size 3 ± 1 nm) throughout the distorted spherical CoFe<inf>2</inf>O<inf>4</inf> major phase (cubic spinel structure with particle size 9 ± 3 nm) showed the best photocatalytic performance for methylene blue (MB) degradation under UV light irradiation at the efficiency of 88.7% and the apparent rate constant (k) of 0.0138 min−1. The 20%CeO<inf>2</inf>/CoFe<inf>2</inf>O<inf>4</inf> photocatalyst had a good magnetic response and could be easily separated from the dye solution by applying an external magnetic field. The reusability test showed lower photodegradation efficiency due to the adsorption of residual MB dye on the photocatalyst surface. The formation of heterojunction at the interfaces of CeO<inf>2</inf>/CoFe<inf>2</inf>O<inf>4</inf> facilitated the photogenerated charge separation and increased availability of active species of holes (h+) and hydroxy radicals (∙OH), which were the key factors in improving the photocatalytic activity.
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Natural wound dressing from acid-modified basil seed mucilage containing aloe vera extract
(2024-01-01)
Seeharaj, Panpailin
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Siriwat, Piyapol
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Phonrat, Arnon
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Prachayawarakorn, Jutarat
There have been several studies that have applied basil)Ocimum basilicum L.(seed mucilage)BSM(as a wound dressing materials using several types of synthetic antimicrobial agents. This research reports on the application of BSM as a green wound dressing using natural substance, namely aloe vera (AV) extract for the improvement of antibacterial activity. Due to poor dimensional stability of BSM, malonic acid (MA) was used to crosslink the BSM molecules. The MA resulted in the esterification reaction between BSM molecules, as revealed by FTIR peak position of the C=O stretching. The porosity, water retention and swelling of BSM sponges were noted to decrease, while stiffness increased upon crosslinking. Incorporation of AV extract into both BSM and MA-crosslinked BSM sponges did not affect hydrophilicity, mechanical properties, thermal properties and cytotoxicity toward HaCaT cells. On the other hand, antibacterial activities against both Gram-positive bacteria)Staphylococcus aureus(and Gram-negative bacteria)Pseudomonas aeruginosa(of BSM and BSM crosslinked by MA were observed upon the addition of the AV extract.
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Alkanolamine-Grafted and Copper-Doped Titanium Dioxide Nanosheets-Graphene Composite Heterostructure for CO2 Photoreduction
(2023-11-13)
Karawek, Apisit
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Kitjanukit, Nutkamol
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Neamsung, Wannisa
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Kinkaew, Chonlathon
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Phadungbut, Poomiwat
CO<inf>2</inf> photoreduction is an intriguing approach to carbon capture, utilization, and storage (CCUS). It relies on an effective photocatalyst to generate photoinduced electrons that incorporate carbon dioxide (CO<inf>2</inf>), yielding fuel products, e.g., methane, methanol, and ethanol. The heterostructure of titanium dioxide nanosheets (TNS) and graphene oxide (GO) is a sandwich-type composite consisting of two 2-dimensional nanostructures (2D-2D). It was demonstrated as an excellent candidate for CO<inf>2</inf> photoreduction due to its outstanding charge separation ability. This research studied the photoactivity of alkanolamine-grafted TNS and alkanolamine-grafted and copper-doped TNS/GO composites. In the first experiment, triethanolamine-grafted TNS (TEA-TNS) exhibited the best ability in CO<inf>2</inf> photoreduction compared to monoethanolamine- and diethanolamine-grafted TNS (MEA-TNS and DEA-TNS) due to the base-catalyzed hydration nature of CO<inf>2</inf>-TEA interactions. In the second experiment, we studied the photoactivity of four composites, including copper-doped TNS/GO (Cu-TNS/GO), TEA-[Cu-TNS/GO] (grafting TEA on Cu-TNS/GO), Cu-[TEA-TNS]/GO (doping Cu on TEA-TNS/GO), and TEA-Cu-TNS/GO (one-step hydrothermal synthesis with the Cu precursor, TEA, and GO). TEA-[Cu-TNS/GO] showed the best photoactivity since TEA was added last to the heterostructures, which benefited in avoiding side chelation reactions between TEA and Cu ions and ensuring TEA exposure to CO<inf>2</inf>

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