Kraiwattanawong, Kriangsak

Preferred name

Alternative Name

Kraiwattanawong, K.

Main Affiliation

School of Engineering

kriangsak.kr@kmitl.ac.th

Now showing 1 - 10 of 23

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Removal of heavy polynuclear aromatics by activated carbons
(2018-01-01)
Pilawan, Wijai
;
Sirikarn, Wisanu
;
Kraiwattanawong, Kriangsak
Heavy polynuclear aromatics (HPNA) is a complex molecules generated during hydrocracking process in waxy oil. HPNA is eliminated by a commercial activated carbon in the absorber to prevent the fouling in the pipelines and the decrease of product yield. In this work, the commercial activated carbons containing the different micropores and the different mesopores were selected to investigate the influence of pore structure on the HPNA removal. Here, the surface area of commercial activated carbons were quite equivalent. The results show that the activated carbon possessing the high mesopores can adsorb HPNA better than the activated carbon having the high micropores in spite of the summation of a micropore volume and a mesopore volume are quite equal. Therefore, the mesopore structure is a major role in the HPNA removal.
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Influence of solvent species used in solvent exchange for preparation of mesoporous carbon xerogels from resorcinol and formaldehyde via subcritical drying
(2011-02-01)
Kraiwattanawong, Kriangsak
;
Tamon, Hajime
;
Praserthdam, Piyasan
Carbon cryogels are dried by 3 days of freeze drying with 6 h of pre-freezing whereas the carbon xerogels are prepared by 1 day of subcritical drying in the selective range of synthesis condition, but the mesoporosity of carbon xerogels are not well controlled. This research is to study the influence of solvent species in the solvent exchange for the preparation of carbon xerogels cooperated by the evaporation drying and the vacuum drying. The good solvent for the high mesoporous properties of carbon xerogels is desirable in the wide range of synthesis condition. The carbon xerogels prepared from resorcinol and formaldehyde were characterized by the nitrogen adsorption apparatus and the field emission scanning electron microscope (FE-SEM). The results illustrate that the mesoporous carbon xerogels in the two subcritical dryings can be easily prepared by solvent exchange. Among the solvents, t-butanol allows the great results in the preparation of high mesoporous carbon xerogels and is well applied in the wide range of synthesis conditions. The FE-SEM images elucidate that the carbon xerogels dried by the vacuum drying contain the particles interconnection larger than the evaporation drying. © 2010 Elsevier Inc. All rights reserved.
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Investigation on porous properties of carbon/carbon composite cryogels by using weighted arithmetic mean
(2016-09-01)
Kraiwattanawong, Kriangsak
;
Sano, Noriaki
;
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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Porosity development of templated porous carbons dried by vacuum as carbon electrodes for electric double-layer capacitors
(2023-03-15)
Kraiwattanawong, Kriangsak
Resorcinol and formaldehyde (RF) resin serves as the carbon precursor for porous carbons and carbon/carbon composites possessing a high specific surface area (SSA). This work presents the porosity improvement by the elimination of cotton fibers (CF) from CF/RF composite hydrogels subsequently exchanged by tertiary butyl alcohol (TBA), dried by vacuum, and carbonized. This route contributes the templated porous carbons (TPC) with an asymmetric structure comprising micropores, mesopores, and macropores. At 0.25 of the CF/RF weight ratio, TPC dried by vacuum apparatus has SSA of 2,102 m2 g−1, whereas TPC dried by evaporation only offers SSA of 663 m2 g−1. Using the vacuum acts as pseudo-freeze drying during TBA removal, forming sponge-like carbon and allowing ultra-high SSA. The electrochemical properties of vacuumed TPCs were analyzed, showing that TPC at 0.25 of the CF/RF weight ratio possessed 626 F g−1 more than TPC at 0.00 of the CF/RF weight ratio which had 392 F g−1 at 200 mA g−1.
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Effects of Nanocrystal Cellulose from Bamboo on the Flexural Strength of Acrylic Resin: In Vitro
(2022-07-01)
Aupaphong, Visakha
;
Kraiwattanawong, Kriangsak
;
Thanathornwong, Bhornsawan
The purpose of this study is to evaluate the effects of nanocrystal cellulose (NCC) from bamboo on the flexural strength of heat-cured acrylic resin. A total of 35 specimens (3.3 mm × 10 mm × 64 mm) were prepared and the specimens were divided into five groups of seven specimens each. Group 1 used conventional acrylic resin that was prepared based on the instructions of the manufacturer (0%). The filled NCC from bamboo fiber in four concentrations (0.25, 0.5, 1, and 2% w/w) was used in the four-reinforcing resin workpiece groups. The specimens were loaded until failure occurred on a three-point bending test machine. One-way analysis of variance and Dunnett’s multiple comparison test at a 95% confidence level were used to determine the statistical differences in the flexural strength among the five groups. The results found that the average flexural strength of five specimen groups (0, 0.25, 0.5, 1, and 2% w/w) were 60.11 ± 2.4, 60.75 ± 2.18, 66.50 ± 5.08, 56.04 ± 0.31, and 48.05 ± 2.61 MPa, respectively. The flexural strength of 0.5 mg% w/w NCC-reinforced acrylic resin was significantly higher than the control group (p < 0.01). The reinforced NCC from bamboo fiber to acrylic resin improved the flexural strength properties.
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Macropore-assisted electrolyte transfer inside binder-free templated carbon xerogels as carbon electrode for electric double layer capacitors
(2020-05-05)
Kraiwattanawong, Kriangsak
Capacitive performance of electric double layer capacitors is influenced by specific surface area, while pore structure also promotes electrolyte transfer inside a carbon electrode. Organic electrolytes require macropores, whereas aqueous electrolytes operate best using mesopores for electrolyte transfer. Templated carbon xerogels (TCXs) were prepared from resorcinol and formaldehyde with cotton fibers as a hard template containing macropores, mesopores and micropores as the carbon electrode. Results suggested that macropores (>50 nm) were contiguously created and connected with mesopore diameters (2–50 nm), leading to convenient ion transport inside the TCXs. Vacuum drying formed sponge-like carbon xerogels that permitted electrolyte transfer. Despite the insignificant change of porous properties, TCXs possessing sponge-like carbon xerogels showed increased capacitance values from 137 F/g to 317 F/g at 200 mA/g in a three-electrode system as a result of macropore-assisted electrolyte transfer in aqueous electrolytes.
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Improvement of the textural properties of templated carbon xerogels using cotton fibres as a hard template dehydrated by sulphuric acid
(2019-02-01)
Kraiwattanawong, Kriangsak
Carbon xerogels have generally low textural properties compared with carbon aerogels and carbon cryogels since the gas-liquid interface produces a capillary force in small pores. In this work, the templated carbon xerogels (TCXs), using resorcinol-formaldehyde (RF) and cotton fibres (CFs) as a hard template, were synthesized by CF removal from CF/RF composite hydrogels by sulphuric acid treatment. The TCX precursors were exchanged by t-butanol, dried by evaporation drying, and carbonized at high temperature. Scanning electron microscope images and Hg intrusion data confirm that TCXs possess macropores whose walls are the carbon xerogel scaffold. Their nitrogen adsorption and desorption isotherms also support that TCXs have micropores and mesopores. The quantities of micropores, mesopores and macropores are improved with the increase of CF utilization. X-ray diffraction allows us to know that TCXs have a graphitic structure. The intensity of D to G from the Raman spectra is also investigated.
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Influence of evaporation drying on the porous properties of carbon/carbon composite xerogels
(2021-08-02)
Kraiwattanawong, Kriangsak
;
Sano, Noriaki
;
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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Preparation of carbon cryogels from wattle tannin and furfural
(2007-01-05)
Kraiwattanawong, K.
;
Mukai, S. R.
;
Tamon, H.
;
Lothongkum, A. W.
Wattle tannin-furfural (TFu) hydrogels were synthesized by the sol-gel polycondensation of wattle tannin with furfural by using three types of base catalysts (NaOH, Na<inf>2</inf>CO<inf>3</inf> and NaHCO<inf>3</inf>). TFu cryogels were prepared by freeze drying of the hydrogels and TFu carbon cryogels were obtained by pyrolysis of the cryogels in an inert atmosphere. The TFu and carbon cryogels were characterized by N<inf>2</inf> adsorption and scanning electron microscope (SEM). The effect of catalysts on porous properties of carbon cryogels resulted in different ways: (1) NaOH enhances increasing mesopore volumes and surface area of carbon cryogels and (2) Na<inf>2</inf>CO<inf>3</inf> and NaHCO<inf>3</inf> cause decreasing those of carbon cryogels. The TFu and carbon cryogels prepared by using NaOH as a catalyst possessed large mesopore volumes comparing with micropore volumes. Even though the TFu cryogels have surface area and mesopore volumes smaller than the resorcinol-formaldehyde (RF) cryogels, the carbon cryogels have unique porous properties differed from the RF carbon gels. The properties are summarized as follows: (1) the mesopore volume changes insignificantly after pyrolysis, (2) the pore radius is increased after pyrolysis and (3) micropores are not greatly developed during pyrolysis. © 2006 Elsevier Inc. All rights reserved.
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Porous properties of carbon/carbon composite xerogels
(2018-01-01)
Kraiwattanawong, Kriangsak
Carbon/carbon composite xerogels are prepared by a vacuum drying technique whereas a carbon cryogel is synthesized by a freeze drying technique to compare the effect of these drying methods at the selective synthesis condition. Resorcinol and formaldehyde are used to prepare a matrix phase and cotton fibers are acted as a disperse phase of the carbon/carbon composite xerogels. Here resorcinol and formaldehyde is utilized to synthesize the carbon cryogel only. The carbon/carbon composite xerogels and the carbon cryogel were analyzed by a nitrogen adsorption apparatus and a field emission scanning electron microscope. The results support that the vacuum drying can decrease the pore shrinkage despite of the gas-liquid interface. The porous properties of the carbon xerogel is quite equivalent to the porous properties of the carbon cryogel. When the porous properties of carbon xerogels are considered, their porous properties can be preserved at the high porosity until 0.15 g/g of the cotton fibers/resorcinol ratio. At 0.25 g/g of this ratio, the porous properties start decreasingly.

Kraiwattanawong, Kriangsak

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