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Adsorptive performance of mesoporous silica-modified Bangkok clay as an alternative GCL
(2026-06-05)
Sathawong, Sidthipong
;
Asadullah
;
Somsiripan, Thotsaporn
;
Tohdee, Kanogwan
;
Jongsomjit, Bunjerd
This study investigates the adsorption performance and characterisation of mesoporous silica-modified Bangkok clay (BKC) as a geosynthetic clay liner (GCL) for removal of heavy metal in aqueous solution. BKC was modified with mesoporous SBA-15 to create a mesoporous silica-coated clay (5SBS), enhancing its surface area, porosity, and adsorption efficiency. The materials were characterized using Fourier-transform infrared spectroscopy, scanning electron microscopy–energy-dispersive X-ray spectroscopy, X-ray diffraction, Brunauer–Emmett–Teller (BET), and X-ray photoelectron spectroscopy techniques while adsorption experiments of Cu(II), Zn(II), and Cd(II) ions under controlled conditions in ternary systems. The 5SBS composite exhibited superior physicochemical characteristics, including a BET surface area of 67.45 m2/g and well-distributed mesopores. Adsorption kinetics followed a pseudo-second-order model, indicating chemisorption as the dominant mechanism. Equilibrium isotherm data fit best with the Langmuir and Sips models, suggesting monolayer adsorption on homogenous surfaces. The maximum uptake capacities for 5SBS were 31.74, 17.96, and 14.26 mg/g for Cu(II), Zn(II), and Cd(II), respectively, outperforming unmodified BKC and closely matching bentonite. Enhanced thermal stability and minimal pore structure degradation post-adsorption confirmed its suitability for harsh environmental conditions. Metal adsorption has mainly occurred at the surface of the mesoporous silica-modified clay by bonding with surface functional groups. Hydraulic conductivity results further indicate that SBA-15 modification effectively reduces permeability and chemical sensitivity of BKC, maintaining performance comparable to bentonite through stable pore-blocking mechanisms. These findings highlight 5SBS as sustainable alternative to bentonite in GCL, with potential implications for contaminant protection.
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Role of alkali and alkaline-earth doped in zeolite A-derived from industrial waste toward direct ethanol dehydrogenation to acetaldehyde
(2026-06-08)
Sukchit, Darunee
;
Prajuabsuk, Malee
;
Inntam, Chan
;
Lumlong, Saisamorn
;
Pakamwong, Bongkochawan
In this study, a sustainable catalytic route for converting ethanol into value-added acetaldehyde was developed using alkali- and alkaline earth-modified zeolite A synthesized from sugarcane bagasse ash (SCBA). Zeolite A was first prepared via alkaline fusion followed by hydrothermal crystallization and subsequently doped with 1 wt% K^+ or Ca^2+ using incipient wetness impregnation. Comprehensive physicochemical characterization (X-ray fluorescence (XRF), X-ray diffraction (XRD), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX), Fourier transform infrared spectroscopy (FTIR), nitrogen physisorption (N_2 physisorption), ammonia temperature-programmed desorption (NH_3-TPD), and carbon dioxide temperature-programmed desorption (CO_2-TPD)) confirmed the formation of a highly crystalline LTA framework with tunable acid-base properties upon cation incorporation. Catalytic evaluation demonstrated that ethanol dehydrogenation strongly depends on the balance of surface acid-base sites. The parent and Ca-modified zeolite A exhibited moderate acetaldehyde selectivity (11.2% and 21.2%, respectively), likely due to competing dehydration reactions. In contrast, K-modified zeolite A achieved higher acetaldehyde selectivity (51.8%) at 35.2% ethanol conversion, attributed to enhanced surface basicity and suppressed acidity. Mechanistic analysis suggests that K^+ and Ca^2+ promote ethanol dehydrogenation by facilitating ethoxide formation and β-hydrogen elimination on basic lattice oxygen sites. These findings demonstrate a cost-effective, noble-metal-free catalytic strategy and highlight the potential of SCBA-derived zeolite A as a sustainable platform for green ethanol upgrading.
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Novel Waste-Derived Cu–Zn/Zeolite A Catalyst for Ethanol Dehydrogenation to Highly Selective Acetaldehyde
(2026-05-05)
Sukchit, Darunee
;
Prajuabsuk, Malee
;
Lumlong, Saisamorn
;
Inntam, Chan
;
Pakamwong, Bongkochawan
A sustainable and highly selective catalyst for ethanol dehydrogenation, Cu–Zn/Zeolite A derived from sugarcane bagasse ash (ZA-SBA), was developed using silica-rich agricultural waste as a low-cost precursor for zeolite A synthesis. Zeolite A was crystallized via hydrothermal treatment of SBA-derived precursors and subsequently modified with 15 wt % Cu and 15 wt % Zn using the incipient wetness impregnation method. Comprehensive characterization (XRF, XRD, SEM-EDX, TEM, FTIR, BET, XPS, NH<inf>3</inf>-TPD, NH<inf>3</inf>–FTIR, and CO<inf>2</inf>-TPD) confirmed the successful formation of zeolite A with enhanced crystallinity, surface area, and basicity. CO<inf>2</inf>-TPD analysis revealed a notable increase in medium-to-strong basic sites (32.76 μmol of CO<inf>2</inf> /g), over three times higher than that of the unmodified support. These basic sites, in synergy with highly dispersed Cu and Zn species, facilitated ethanol activation and hydride elimination while suppressing dehydration and etherification side reactions. In gas-phase ethanol dehydrogenation, the Cu–Zn/ZA-SBA catalyst exhibited outstanding performance, achieving 56.5% ethanol conversion and 99.7% selectivity toward acetaldehyde at 350 °C. This superior activity is attributed to the cooperative interaction between Cu and Zn species and the tailored acid–base surface properties of the SBA-derived zeolite A support. The present work demonstrates the valorization of sugarcane bagasse ash into functional zeolitic materials, providing a green, low-cost, and efficient strategy for developing sustainable catalysts for bioethanol upgrading into value-added acetaldehyde.
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Synthesis and Characterization of Zeolite A from Industrial Fly Ash as a Green, Cost-Effective Cd2+ and Pb2+ Adsorbent for Wastewater Applications
(2025-02-18)
Sukchit, Darunee
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Prajuabsuk, Malee
;
Lumlong, Saisamorn
;
Inntam, Chan
;
Punkvang, Auradee
According to the large amount of fly ash waste generated from the use of lignite coal as the primary fuel for electricity generation in the Mae Moh district of Lampang province, Thailand, efforts have been made in waste management to reduce and repurpose this industrial byproduct. In this study, lignite coal fly ash was used to synthesize zeolite A adsorbents for the treatment of wastewater contaminated with heavy metals. Characterization of the synthesized zeolite using XRD, XRF, BET, and SEM methods confirmed that it is zeolite A, with a calculated Si/Al molar ratio of approximately 1.19, closely matching the theoretical ratio of zeolite A. This zeolite A exhibited a high crystalline phase and a mesoporous structure, having a specific surface area of 37.10 m2/g and a total pore volume of 0.06 cm3/g. The performance of this zeolite A was evaluated for the adsorption of Cd2+ and Pb2+ in prepared solutions. The removal efficiencies of zeolite A for Cd2+ and Pb2+ were 99.65% ± 0.1% and 93.90% ± 0.5%, with maximum adsorption capacities of 17.3 ± 0.6 and 8.8 ± 0.1 mg/g, respectively. Additionally, zeolite A demonstrated reusability for the adsorption of Cd2+ and Pb2+, maintaining a removal efficiency of 80.52% ± 0.1% for Cd2+ over five reuse cycles, and 96.83% ± 0.7% for Pb2+ over one reuse cycle. The adsorption of Cd2+ and Pb2+ by zeolite A followed the Langmuir isotherm model and pseudo-second-order kinetic model. Moreover, the adsorption of Cd2+ and Pb2+ by zeolite A was found to be a spontaneous, endothermic process, as evidenced by increasingly negative Gibbs free energy change (ΔG°) values with rising temperature. Density functional theory (DFT) calculations were also performed to investigate the binding of Cd2+ and Pb2+ ions to zeolite A, providing insight into why Cd2+ exhibits a slightly higher affinity than Pb2+. The results showed that Cd2+ ions have a marginally greater affinity for zeolite A compared to Pb2+ (−85.72 vs −85.39 kcal/mol), which aligns with experimental findings. This study offers an alternative approach for reducing industrial waste by repurposing it for valuable applications, contributing to sustainable waste management practices that align with the principles of the bio-circular-green economy.
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Determining the role of oxygen vacancies in palmitone selectivity and coke formation over acid metal oxide catalysts for the ketonization of methyl palmitate
(2021-11-25)
Guntida, Adisak
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Rattanachartnarong, Thanwarat
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Jongsomjit, Bunjerd
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Sooknoi, Tawan
;
Weerachawanasak, Patcharaporn
In the present study, TiO<inf>2</inf>, CeO<inf>2</inf>, MnO<inf>2</inf>, and ZrO<inf>2</inf> catalysts were used to investigate the catalytic performance in methyl palmitate ketonization. The reaction was accelerated by weak Lewis acid, while the oxygen vacancies promoted the palmitone selectivity. The use of various characterization techniques revealed that oxygen vacancies played an important role for trapping the hydrogen atom and inhibited its spillover. This caused the suppression of the Lewis acid transformation to new Bronsted acid. Thus, the cracking of palmitone over the new Bronsted acid was diminished, leading to the decrement of selectivity to undesired products. However, when the hydrogen atom was trapped in the oxygen vacancies, the coke deposition was dominant. This phenomenon arose because hydrogen could not suppress the deep dehydrogenation, resulting in the transformation of aliphatic coke to aromatic coke. The role of oxygen vacancies was determined, and it had the positive effect on the palmitone selectivity, whereas it raised the coke formation.

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