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Innovative eco-friendly methyl orange removal: Mechanism, kinetic, and thermodynamic study using starch cryogel-integrated mesoporous silica nanoparticles
(2024-11-15)
Taweekarn, Tarawee
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Wongniramaikul, Worawit
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Sriprom, Wilasinee
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Limsakul, Wadcharawadee
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Phawachalotorn, Chanadda
This study introduces a novel, eco−friendly composite, uncalcined mesoporous silica nanoparticles incorporated into a starch cryogel (MSNs-Cry), designed for the effective removal of methyl orange (MO) from water. MSNs−Cry integrates uncalcined mesoporous silica nanoparticles (MSNs) within a starch cryogel network, leveraging the high adsorption capacity of MSNs. The composite achieved a maximum adsorption capacity of 18.98 mg g⁻1 and demonstrated high removal efficiencies of 99.00 % ± 0.21 % in synthetic water (10 mg L−1 MO) and 92.77 % ± 1.76 % in real wastewater containing 0.43 mg L−1 MO. The Langmuir isotherm model provided a superior fit (R2 = 0.9930) compared to the Freundlich model (R2 = 0.9180), and the adsorption kinetics followed a pseudo−second−order model (R2 = 0.9917). The primary adsorption mechanisms included electrostatic attraction, hydrophobic interactions, and hydrogen bonding. The process was endothermic (ΔH° = 31.3 kJ mol−1), spontaneous, and more favorable at higher temperatures (ΔG° = −34.2 to −38.6 kJ mol−1 at 298–318 K). In the presence of sodium silicate at 13.1 times the MO concentration, removal efficiency drops by 35.77 %, and with sodium sulfate and urea at 100 times the MO concentration, it decreases by 8.65 %. Despite these challenges, MSNs−Cry effectively removes MO in the presence of the anionic dye Congo Red and metal ions, demonstrating its selective adsorption capabilities. The tablet form of MSNs−Cry prevents the loss of uncalcined MSNs, mitigating potential environmental and operational impacts. Additionally, the composite's effectiveness at a natural pH of 6.65 eliminates the need for pH adjustment, offering a cost−effective solution for real−world applications. This study establishes MSNs−Cry as a promising material for sustainable water purification.
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Effective recovery of phosphate from wastewater using biodegradable calcium-rich shell wastes composite macroporous cryogel
(2024-06-20)
Kaewnoo, Satabodee
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Wongniramaikul, Worawit
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Boonkanon, Chanita
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Taweekarn, Tarawee
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Kleangklao, Bussakorn
The recovery of phosphorus from wastewater holds promise as a sustainable source of organic phosphorus for agricultural use while aiding in meeting legislative discharge limits for phosphorus to control and mitigate eutrophication. This study introduces a novel approach in which calcium-rich calcined oyster shell (Ca–COS) is immobilized on a starch-based monolithic cryogel, resulting in a green tablet (Cry–Ca–COS) capable of efficiently recovering phosphate from water through chemisorption on the material surface and precipitation in the liquid phase. The formed tablet prevents sorbent loss post-adsorption, facilitating reusability. Under optimal conditions (i.e., three 0.83 cm thick Cry–Ca–COS tablets, an initial phosphate concentration of 12 mg L−1 in 1 L without pH adjustment (pH 6.3), and a contact time of 60 minutes), a phosphate removal efficiency of 83.11% ± 0.68% and a maximum removal capacity of 9.97 mg g−1 were achieved. Both the Langmuir isotherm model and pseudo-second-order kinetic model exhibited good fits to the experimental data, with an estimated activation energy of 81.9 kJ mol−1 and a positive enthalpy of 9.3 kJ mol−1, indicating an endothermic chemisorption process with a monolayer surface coverage of phosphate on Cry–Ca–COS. In real samples, Cry–Ca–COS demonstrated a high removal efficiency ranging from 98.48% ± 1.87%–99.16% ± 0.72%, with the adsorbed material biodegrading within 24 days under soil burial conditions. A preliminary study was conducted to explore the feasibility of utilizing phosphate-adsorbed Cry–Ca–COS as a fertilizer for cultivating water spinach (Ipomoea aquatica Forsk.), and further in-depth investigation is required for a comprehensive report in the future. Thus, Cry–Ca–COS emerges as an environmentally friendly and effective tool for phosphate removal and recovery.
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Self-healing carbon fiber-reinforced polymers for aerospace applications
(2022-08-29)
Chuangchote, Surawut
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Nukunudompanich, Methawee
Self-healing carbon fiber-reinforced polymers (CFRPs) have been explored in-depth since the 2000s. Microcapsules, vascular networks, dissolved thermoplastics, and reversible interactions can be used to give polymer matrix composites with self-healing properties. Recent improvements, particularly epoxy employed as a matrix phase in carbon fiber-reinforced polymers, are chosen and examined in terms of their repair mechanisms, validation testing methods, and any other attributes that might be relevant in aerospace applications. Extrinsic self-healing, which is pioneered in this field, paves the way for more modern approaches that take advantage of intrinsic self-molecular healing pathways. The latter appears to be the more promising self-healing carbon fiber-reinforced polymers in the long run. Self-healing carbon fiber-reinforced polymers are critical for increasing aircraft fatigue, impact, and corrosion resistance. Complex aviation composite geometries that are formerly made using time-consuming and expensive techniques (e.g. autoclave) can now be made utilizing simpler (and hence less expensive) processes, such as co-electrospinning, vacuum-assisted injection molding, or hand-lay up molding. Engines, fuselages, and aerostructures, as well as anticorrosion coatings, have profited from the usage of self-healing carbon fiber-reinforced polymers. Each area demands its own set of processes for improvement. Anyhow, carbon fiber-reinforced polymers face some problems of disposal and recycling.
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Influence of evaporation drying on the porous properties of carbon/carbon composite xerogels
(2021-08-02)
Kraiwattanawong, Kriangsak
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Sano, Noriaki
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Tamon, Hajime
Carbon/carbon (C/C) composite xerogels dried by evaporation were prepared in this study to observe the change of their porous properties and their morphology by nitrogen sorption apparatus and a scanning electron microscope. Resorcinol and formaldehyde (RF) sols as a matrix phase and cotton fibers (CF) as a dispersed phase were mixed and gelated to be CF/RF composite hydrogels. The composite hydrogels were exchanged by t-butanol (TBA), dried by evaporation at 50◦C, and carbonized at 1000◦C to become the C/C composite xerogels. The results show that the CF addition does not decrease the mesoporous properties of the C/C composite xerogels. Moreover, the CF addition can alleviate the pore shrinkage, and it can maintain the mesopore structure. The mesopore size and the micropore size of C/C composites are insignificantly changed because the CF addition and the solvent exchange using TBA may suppress the pore shrinkage despite the gas-liquid interface existing during the evaporation drying.
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Electrical properties of bistable device based on graphene oxide composited with polyvinylpyrrolidone thin films
(2021-01-01)
Thiwawong, Thutiyaporn
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Songkeaw, Potiyan
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Onlaor, Korakot
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Tunhoo, Benchapol
This research studied the bistable properties of synthesized graphene oxide (GO) composited with polyvinylpyrrolidone (PVP). The devices were fabricated using a spin coating process on indium tin oxide (ITO)/glass substrate, and the top electrodes were prepared by thermal evaporation with the device structure of ITO/PVP:GO/Al. The PVP:GO films were characterized by Raman spectroscopy, Fourier-transform infrared spectroscopy, X-ray photoemission spectroscopy, and scanning electron microscopy. The current-voltage (I-V) characteristics of the fabricated device exhibited a maximum ON/OFF current ratio in the order of about 104 at a GO concentration of 4 wt%. The mechanism was explained by fitting with the results of the I-V measurement. Moreover, the retention test of the device was more than 2×104 s. The device showed the important characteristics of memory to be a candidate for data storage.
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Flexible and fully transparent WORM memory devices based on Ag nanoparticles blended with poly(ethylene-co-vinyl acetate)
(2019-12-01)
Onlaor, Korakot
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Thiwawong, Thutiyaporn
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Tunhoo, Benchapol
Silver nanoparticles (Ag NPs) blended with poly(ethylene-co-vinyl acetate) (EVA) were used as an active layer to fabricate flexible and fully transparent memory devices by using the spin-coating method followed by the thermal roll lamination technique with the structure of ITO/EVA:Ag NPs/ITO. The devices exhibited a non-volatile write-once-read-many-times (WORM) memory type and possessed current bi-stability with ON/OFF current ratio within the range of 104-105 at a reading voltage of +1 V. The data continuous read operations reached more than 10 h, which revealed the stability of the memory devices over a long period of time. The conduction mechanisms of the memory device could be explained by theoretical models and proposed by electron trapping at the trapping center of Ag NPs inside the EVA matrix. In addition, the memory device showed a fast response of 231 ns and was fully transparent with maximum transmittance of the device at 83.2%. Further, the devices could be operated under the bending condition of more than 0.83% strain.
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Optical absorption and FTIR study of cellulose/tio2hybrid composites
(2019-05-01)
Plermjai, Kittiya
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Boonyarattanakalin, Kanokthip
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Mekprasart, Wanichaya
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Phoohinkong, Weerachon
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Pavasupree, Sorapong
Cellulose/TiO<inf>2</inf> composite was prepared by conventional mixing using distilled water as medium. The structure and relevant properties of cellulose/TiO<inf>2</inf> composite were characterized by X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and UV- Vis spectroscopy. XRD results exhibit typical cellulose structure type I. The absorbance spectra of TiO<inf>2</inf>and cellulose exist in vicinity of 200 nm and 350 nm in the UV range, corresponding to the UV-C, UV-B and UV-A. In addition, the UV absorption band of the composite can be extended covering wide UV region. Corresponding FTIR results suggest the existence of chemical bonding or surface interaction between TiO<inf>2</inf> and cellulose.
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Effect of neem wood sawdust content on properties of biodegradable thermoplastic acetylated cassava starch/neem wood sawdust composites
(2017-03-01)
Prachayawarakorn, Jutarat
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Hanchana, Areeya
Due to several important limitations for applications of thermoplastic starch (TPS), thermoplastic acetylated cassava starch (TPACS) polymer was reinforced by different contents of neem wood sawdust (SD). Thermoplastic cassava starch (TPCS)/SD composites were also prepared and reinforced by different SD contents and compared with the TPACS/SD composites. Morphological, thermal, and biodegradable properties of different composites were also examined. The results showed that IR absorption bands of OH stretching and OH bending vibrations shifted to lower wavenumbers, indicating new hydrogen bond formation for all composites. Stress at maximum load and Young's modulus were significantly improved when the SD content increased for all the TPACS/SD and TPCS/SD composites; strain at maximum load was higher for the TPACS/SD composites. A decrease in water uptake was detected when the SD reinforcement was incorporated into either the TPACS or TPCS matrix.
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Investigation on porous properties of carbon/carbon composite cryogels by using weighted arithmetic mean
(2016-09-01)
Kraiwattanawong, Kriangsak
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Sano, Noriaki
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Tamon, Hajime
Cotton fibers (CF) and resorcinol and formaldehyde (RF) sol were used to synthesize composite cryogels. They were carbonized to prepare carbon/carbon (C/C) composite cryogels. In this work, the molar ratio of resorcinol to sodium carbonate (R/C), the mass concentration of resorcinol to distilled water (R/W) and the mass ratio of CF to RF (CF/RF) were changed as 100 and 200 mol/mol, 0.25 and 0.50 g/cm3 and 0.00 up to 0.64 g/g, respectively. The C/C composites were characterized by nitrogen adsorption and scanning electron microscopy. The results showed that the mesopore structure of C/C composites could be controlled by the adjustment of an R/W or R/C ratio. Moreover, the mean micropore sizes of C/C composite cryogels were kept equivalently to those of normal carbon cryogels. The weighted arithmetic mean was well applied to the BET surface area and micropore surface area of C/C composites with the deviation of about 21% for the high R/C ratio; however, it poor for the low R/C ratio. The weighted arithmetic mean also estimated the micropore volume of C/C composite cryogels with the deviation of about 20% for the CF/RF ratio smaller than 0.40 g/g. Moreover, the weighted arithmetic mean can be used as a guideline to estimate the mesopore volume.
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Effect of pectin particles and cotton fibers on properties of thermoplastic cassava starch composites
(2016-03-01)
Prachayawarakorn, Jutarat
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Pattanasin, Worawan
Due to poor mechanical properties and high water uptake of thermoplastic starch (TPS), this research focused on property improvement of thermoplastic cassava starch (TPCS) using natural compatible polymers, i.e. pectin particles and cotton fibers. Different TPCS composites, reinforced by the pectin particles and/or the cotton fibers, were compounded and shaped using an internal mixer and a compression molding machine, respectively. It was found from infrared (IR) spectra that the peak position of O-H stretching of the TPCS polymer clearly shifted to lower wavenumber by the addition of the pectin particles and/or the cotton fibers. Moreover, the significant increase of stress at maximum load and Young’s modulus of the TPCS/pectin particle and the TPCS/cotton fiber composites was observed. The drop of water uptake was also found when the cotton fibers were incorporated into the TPCS matrix with/without pectin particles. In addition, X-Ray Diffraction, Scanning Electron Microscopy and Thermogravimetric Analysis were used to characterize different TPCS composites.

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