• Korean Journal of Materials Research
• /
• v.34 no.1
• /
• pp.1-11
• /
• 2024

This research investigated the preparation of activated carbon derived from Krabok (Irvingia malayana) seed shells to improve the quality of crude glycerol obtained during biodiesel production. The activated carbon was prepared using a dry chemical activation method with NaOH, utilizing an innovative biomass incinerator. The results revealed that the resulting KC/AC-two-step exhibited favorable physicochemical adsorption properties, with a high surface area of 758.72 m²/g and an iodine number of 611.10 mg/g. These values meet the criteria of the industrial product standard for activated carbon No. TIS 900-2004, as specified by the Ministry of Industry in Thailand. Additionally, the adsorption efficiency for methylene blue reached an impressive 99.35 %. This developed activated carbon was then used to improve the quality of crude glycerol obtained from biodiesel production. The experimental results showed that the KC/AC-two-step increased the purity of crude glycerol to 73.61 %. In comparison, commercially available activated carbon (C/AC) resulted in a higher crude glycerol purity of 81.19 %, as analyzed by the GC technique. Additionally, the metal content (Zn, Cu, Fe, Pb, Cd, and Na) in purified glycerol using KC/AC-two-step was below the standards for heavy metals permitted in food and cosmeceuticals by the Food and Drug Administration of Thailand and the European Committee for Food Contact Materials and Articles. As a result, it can be inferred that Krabok seed shells have favorable properties for producing activated carbon suitable as an adsorbent to enhance crude glycerol purity. Furthermore, the improved crude glycerol from this research has potential for various industrial applications.

• Korean Journal of Materials Research
• /
• v.12 no.11
• /
• pp.860-864
• /
• 2002

$Li^{+}$ extraction reactions with ion-exchange type lithium manganese oxide in an aqueous phase were examined using chemical and x-ray diffraction (XRD) analysis. In the process of extraction reaction, the lithium manganese oxide showed a topotactic extraction of $Li^{+ }$ in the aqueous phase mainly through an ion-exchange mechanism, and the $Li^{+}$ extracted samples indicated a high selectivity and a large capacity for $Li^{+}$ . The electronic structures and chemical bonding properties were also studied using a discrete variational (DV)-X$\alpha$ molecular orbital method with cluster model of (Li$Mn_{12}$ $O_{40}$ )$^{27-}$ for tetrahedral sites and ($Li_{7}$ Mn $O_{38}$ )$^{3}$ for octahedral site in $Li_{1.33}$ $Mn_{1.67}$ / $O_{4}$ respectively. Li in the manganese oxides is highly ionized in both sites, but the net charge of Li was greater for tetrahedral sites than octahedral. These calculations suggest that the tetrahedral sites have higher $Li^{+}$ $H^{+}$ exchangeability than the octahedral sites, and are preferable for the selective adsorption for L $i^{+}$ ions.s.

• Clean Technology
• /
• v.11 no.2
• /
• pp.69-74
• /
• 2005

A metal ion detector with a submicron size electrode was fabricated by field-induced AFM oxidation. The square frame of the mesa pattern was functionalized by APTES for the metal ion detection, and the remaining portion was used as an electrode by the self-assembly of MPTMS for Au metal deposition. The conductance changed with the quantity of adsorbed copper ions, due to electron tunneling between the mobile and surface electrodes. The smaller electrode has a lower limit of detection due to the enhancement in electron tunneling through metal ions that are adsorbed between the conductive-tip (mobile) and the surface (fixed) electrode. This two-electrode system immobilized with different functional groups was successfully used in the selective adsorption and detection of target materials.

• Carbon letters
• /
• v.22
• /
• pp.1-13
• /
• 2017

Porous materials play a vital role in science and technology. The ability to control their pore structures at the atomic, molecular, and nanometer scales enable interactions with atoms, ions and molecules to occur throughout the bulk of the material, for practical applications. Three-dimensional (3D) porous carbon-based materials (e.g., graphene aerogels/hydrogels, sponges and foams) made of graphene or graphene oxide-based networks have attracted considerable attention because they offer low density, high porosity, large surface area, excellent electrical conductivity and stable mechanical properties. Water pollution and associated environmental issues have become a hot topic in recent years. Rapid industrialization has led to a massive increase in the amount of wastewater that industries discharge into the environment. Water pollution is caused by oil spills, heavy metals, dyes, and organic compounds released by industry, as well as via unpredictable accidents. In addition, water pollution is also caused by radionuclides released by nuclear disasters or leakage. This review presents an overview of the state-of-the-art synthesis methodologies of 3D porous graphene materials and highlights their synthesis for environmental applications. The various synthetic methods used to prepare these 3D materials are discussed, particularly template-free self-assembly methods, and template-directed methods. Some key results are summarized, where 3D graphene materials have been used for the adsorption of dyes, heavy metals, and radioactive materials from polluted environments.

• KSBB Journal
• /
• v.10 no.1
• /
• pp.105-112
• /
• 1995

The fiber-optic biosensor using enzyme-immobilized Langmuir-Blodgett film is developed fort the measurement of ethanol. The enzyme, alcohol dehydrogenase, is immobilized at the molecular level on the arachidic acid monolayer using Langmuir-Blodgett film technique. Based on the ordered multisubstrate mechanism, the immobilized enzyme kinetics is investigated. The optical sensing system is proposed, and sensor signal is proportional to ethanol concentration and is related wish the number of enzyme layers. As the number of deposited LB film layer increases up to 20 1ayers, the high ethanol concentration of 45mM can be measured without the saturation of signal. Surface pressure-area isotherm is measured for the three-different charged-lipids. Arachidic acid is the most suitable for the adsorption of alcohol dehydrogenase based on electrostatic force.

• Journal of the Korean Magnetic Resonance Society
• /
• v.9 no.1
• /
• pp.1-20
• /
• 2005

Vanadium-incorporated aluminophophate molecular sieve VH-SAPO-11 has been studied by electron spin resonanace (ESR) and electron spin echo modulation (ESEM) spectroscopies to determine the vanadium locatin and interaction with various adsorbate molecules. As-synthsized VH-SAPO-11 contains only vanady1 species with distored octahral coordination. After calcinations in $O_2$ and exposure to moisture, only species A is observed with reduced intensities. Species A is suggested as a VO$(H_2O)_2^{2+$} complex coordinate to three framwork oxygen bonded to aluminum. When calcined, hydrate VH-SAPO-11 is dehydrated at elevated temperature, species A loses it water ligands and transforms to $VO^{2+}$ ions coordinated to three framework oxygens (species B). Species B reduces its intensities significantly after treatment with $O_2$at high temperature, thus suggesting oxidation of $v^{4+}$to $v^{5+}$. When dehydrated VH-SAPO-11 contacts with $D_2O$ at room temperature, the ESR signal of species A is observed. This species assumed as a $VO(O_f)_3(D_2O)_2$, by considering 3 framework oxygens. Adsorption of deuterated methanol on dehydrated VH-SAPO-11 results in another new vanadium species D, which is identified as a $VO(CD_{3}OH)$ complex. When deuterated ethanol is adsorbed on dehydrated VH-SAPO-11, another new vanadium species E identified as a $VO(C_{2}H_{5}OD)^{2+}$, is observed. When deuterated propanol is adsorbed on dehydrated VH-SAPO-11, a new vanadium species F identified as a $VO(C_{3}H_{7}OD)$, is observed. Possible coordination geometries of these various complexes are discussed.

• Polymer(Korea)
• /
• v.36 no.3
• /
• pp.364-371
• /
• 2012

Polystyrene/single-walled carbon nanotube (PS/SWCNT) nanocomposites were prepared by latex technology and the effect of surfactant (SDS) on nanotube dispersion, rheological and electrical properties was investigated. The nanocomposites were prepared through freeze-drying after mixing PS particles and aqueous SWCNT/SDS suspension. As the SDS content increased, the storage modulus and complex viscosity of the nanocomposites were increased due to enhanced dispersion of nanotubes, but if the content excessively increased, the modulus and viscosity began to decrease due to low molecular weight of SDS. The electrical conductivity sharply increased with the addition of SDS, and then did not show significant changes. This result is speculated to be the competition between the increased dispersion of nanotubes and the deterioration of electrical conductivity by SDS adsorption. An optimal ratio of SDS to SWCNT for improving electrical conductivity and end-use properties was 2. With this ratio, the electrical percolation threshold of SWCNT was less than 1 wt%.

• Journal of Environmental Science International
• /
• v.10 no.1
• /
• pp.59-64
• /
• 2001

The effect of major operating parameters in spray drying sorber(=SDS) for automatic control for the simultaneous removal of acidic and organic gaseous pollutants from solid waste incinerator was performed. The field experiment was carried out in pilot scale test for the quantification of major operating parameters of hydrophilic and the hydrophobic pollutants. The removal efficiencies of $SO_2$and HCI in the 5wt% slurry condition were being increased with the increase of the stoichiometric ration which is the molecular ratio of lime to the pollutant concentration, and with the decrease of inflow flue gas temperature in the pilot SDS reactor. The removal efficiency along the height of spray drying sorber was closely related to the temperature profile, and more than 90% of total removal efficiency was achieved in an absorption region. For the removal of acidic gas the optimum operating condition considering the economics and a stable operation is the 5wt% of slurry concentration, 1.2 of stoichiometric ratio and 25$0^{\circ}C$ of inflow flue gas temperature. For the organic gases of benzene and toluene the removal efficiencies were 20-60% which is much lower than that of acidic gas. The best removal efficiency was obtained at 1.5 of stoichiometric ratio and 25$0^{\circ}C$ of inflow flue gas temperature. The organic\`s removal efficiency along the height of spray drying sorber was quite different from that of acidic gas, that is, more than 60% of the total removal efficiency for benzene and 90% of the total removal for toluene were achieved in the dried adsorption region, which was formed at the lower or exit part of the reactor.

• Journal of the Korean Chemical Society
• /
• v.21 no.4
• /
• pp.246-255
• /
• 1977

The adsorption of methylmethacylate on layer silicates containing various interlayer cations has been studied by means of infrared spectroscopy and X-Ray. Several characteristic carbonyl bands of adsorbed methylmethacrylate appeared differently at the region of 1723∼1547$cm^{-1}$depending on the species of cation and the dehydration temperature. The carbonyl stretching band shifted about 190$cm^{-1}$ to lower frequencies has been observed only for polyvalent cations, which has been attributed to $>C=O{\cdot}{\cdot}{\cdot}M^{n+}$ complex formation. The band appeared at 1703∼1640$cm^{-1}$ is responsible for hydrogen bonding between carbonyl oxygen and cationic water or cationic hydroxyl group, and the degree of shift indicates good correlation with the polarizing power of the interlayer cations. However, the band appeared at 1723$cm^{-1}$ has not been correlated with the species of cation but assigned to the carbonyl stretching which reacted with the surface hydroxyl group. On the basis of interlamellar spacing, it is suggested that the molecular plane of MMA molecule is parallel to silicate layers.

• Journal of Microbiology and Biotechnology
• /
• v.22 no.1
• /
• pp.58-68
• /
• 2012

An investigation was conducted on the enhancement of production and purification of an oxidant and SDS-stable alkaline protease (BHAP) secreted by an alkalophilic Bacillus horikoshii, which was screened from the body fluid of a unique Korean polychaeta (Periserrula leucophryna) living in the tidal mud flats of Kwangwha Island in the Korean West Sea. A prominent effect on BHAP production was obtained by adding 2% maltose, 1% sodium citrate, 0.8% NaCl, and 0.6% sodium carbonate to the culturing medium. The optimal medium for BHAP production contained (g/l) SBM, 15; casein, 10; $K_2HPO_4$, 2; $KH_2PO_4$, 2; maltose, 20; sodium citrate, 10; $MgSO_4$, 0.06; NaCl, 8; and $Na_2CO_3$, 6. A protease yield of approximately 56,000 U/ml was achieved using the optimized medium, which is an increase of approximately 5.5-fold compared with the previous optimization (10,050 U/ml). The BHAP was homogenously purified 34-fold with an overall recovery of 34% and a specific activity of 223,090 U/mg protein using adsorption with Diaion HPA75, hydrophobic interaction chromatography (HIC) on Phenyl-Sepharose, and ion-exchange chromatography on a DEAE- and CM-Sepharose column. The purified BHAP was determined a homogeneous by SDS-PAGE, with an apparent molecular mass of 28 kDa, and it showed extreme stability towards organic solvents, SDS, and oxidizing agents. The $K_m$ and $k_{cat}$ values were 78.7 ${\mu}M$ and $217.4s^{-1}$ for N-succinyl-Ala-Ala-Pro-Phe-pNA at $37^{\circ}C$ and pH 9, respectively. The inhibition profile exhibited by PMSF suggested that the protease from B. horikoshii belongs to the family of serine proteases. The BHAP, which showed high stability against SDS and $H_2O_2$, has significance for industrial application, such as additives in detergent and feed industries.