• Applied Chemistry for Engineering
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• v.17 no.3
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• pp.280-285
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• 2006

Adsorption characteristics of $H_{2}S$ on KOH impregnated activated carbon were evaluated using dynamic adsorption method in a fixed bed. The pore properties, including BET's specific surface area, pore volume, pore size distribution, and mean pore diameter of these KOH impregnated activated carbons, were characterized from $N_{2}$ adsorption/desorption isotherms. Adsorption equilibrium data were correlated with Langmuir and Freundlich isotherms. The adsorption of $H_{2}S$ onto the KOH impregnated activated carbon is better fitted by the Langmuir isotherm. An increase in the content of oxygen affects the performance of KOH impregnated activated carbon to the greatest extent.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.6
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• pp.673-679
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• 2008

In this study, Mesoporous silica were prepared from hydrothermal synthesis using gel mixture of tetraethylorthosilcate (TEOS) as silica source and cetyltrimethylammonium bromide(CTMABr) as a template. In the optimum synthesis cause, molar ratio of template and silica changed. The surface and structure properties of Mesoporous silica were determined by XRD, SEM, and BET. N$_2$ adsorption isotherm characteristics, including the specific surface area(S$_{BET}$), total pore volume(V$_T$), and average pore diameter(D$_{BJH}$), were determined by BET. Also, the adsorption character of Pb(II) and Cd(II) ion on Mesoporous silica were measured using ICP. As a result, a SBET of 100$\sim$1,500 m$^2$/g was determined from the N$_2$ adsorption isotherm. Also, the average pore diameter of 2$\sim$4 nm. The adsorption of Pb ion and Cd ion on Mesoporous silica become different depending on the pH of solution. The adsorption amount of Mesoporus silica had higher than that of silicagel.

• Applied Biological Chemistry
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• v.44 no.3
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• pp.185-190
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• 2001

Alginate, a well-known biopolymer, is universally applied for immobilization of microbial cells. Biosorption characteristics of lead by waste biomass of immobilized A. niger beads, used in fermentation industries to produce citric acid, were studied. The immobilized A. niger beads, prepared via capillary extrusion method using calcium chloride, were applied in the removal of lead. Pb uptake was the highest in A. niger beads cells grown for 3 days with medium producing citric acid (12% sucrose, 0.5% $NH_4NO_3$, 0.1% $KH_2PO_4$, and 0.025% $MgSO_4$). Lead uptake by the immobilized A. niger beads and free A. niger mycellia beads increased sharply with time. However, while uptake by the immobilized A. niger beads continued to increase slowly, that by free A. niger mycellia beads stopped after 30 min. The optimum pH and temperature of lead uptake were found to be 6 and $35^{\circ}C$, respectively. The maximum uptake of lead was achieved with $50{\sim}100$ beads and 50 ml lead solution in a 250-ml Erlenmeyer flask, while, at over 100 beads, uptake of the lead decreased. The order of biosorption capacity for heavy metals was Pb>Cu>Cd. Pb uptake capacity of the immobilized A. niger beads treated with 0.1 M $CaCI_2$, 0.1 M NaOH, and 0.1 M KOH decreased compared to the untreated beads. On testing the desorption of Pb from the immobilized A. niger beads, re-uptake of Pb was found possible after desorption of the binding metal with 0.1 M HCI.

• Applied Chemistry for Engineering
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• v.31 no.2
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• pp.164-171
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• 2020

Adsorption characteristics of reactive red 120 (RR 120) dye by a coal-based granular activated carbon (CGAC) from an aqueous solution were investigated using the amount of activated carbon, pH, initial concentration, contact time and temperature as adsorption variables. Isotherm equilibrium relationship showed that Langmuir's equation fits better than that of Freundlich's equation. The adsorption mechanism was considered to be superior to the adsorption of monolayer with uniform energy distribution. From the evaluated Langmuir separation coefficients (R_L = 0.181~0.644), it was found that this adsorption process belongs to an effective treatment area (R_L = 0~1). The adsorption energy determined by Temkin's equation and Dubinin-Radushkevich's equation was E = 15.31~7.12 J/mol and B = 0.223~0.365 kJ/mol, respectively. The adsorption process showed the physical adsorption (E < 20 J/mol and B < 8 kJ/mol). The adsorption kinetics followed the pseudo first order model. The adsorption reaction of RR 120 dye on CGAC was found to increase spontaneously with increasing the temperature because the free energy change decreased with increasing the temperature. The enthalpy change (12.747 kJ/mol) indicated an endothermic reaction. The isosteric heat of adsorption (△H_x = 9.78~24.21 kJ/mol) for the adsorption reaction of RR 120 by CGAC was revealed to be the physical adsorption (△H_x < 80 kJ/mol).

• Journal of Life Science
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• v.16 no.6
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• pp.877-883
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• 2006

An alternative method to remove and recover heavy metals is biosorption based on metal-sequestering properties of natural or biological origin. In this study, the effects of factors such as temperature, pH, initial concentration of lead, and initial amount of biomass on biosorption of lead using Aureobasdium pullulans were investigated. A. pullulans has an excellent selectivity to remove lead than other heavy metals such as cadmium, chromium, nickel in pure and mixed solution. The optimum temperature of biosorption with A. pullulans was $40^{\circ}C$ and the amount of removal increased at high pH. The higher initial lead concentration or the lower cell dry weight, the higher amount of lead was adsorbed. The adsorption isotherm of lead was accorded with Freundlich model. The adsorption capacity and initial adsorption rate of living A. pullulans were about twice higher than that of dead one.

• Proceedings of the Korean Fiber Society Conference
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• 1997.04a
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• pp.26-31
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• 1997

유리섬유/nylon 6 복합재료의 계면결합강도를 증가시키기 위하여 r-APS(r-Aminopropyltriethoxysilane)로 유리섬유의 표면을 처리 하였다. 이때 표면처리의 최적 조건을 찾기위해서 처리후 기기분석과 계면결합강도 측정 등을 하였다. 농도, pH, 처리시간, 온도를 변화시키면서 표면처리를 한 후 흡착량을 살펴본 결과 처리 농도에 의해서는 흡착량이 단조증가하였으며 처리시간에 따라서는 5분정도에서, 처리온도에 의해서는 30C 부근에서 최대 흡착량을 보였다. 또한 pH에 따른 흡착량은 silane의 고유 pH인 10.5부근에서 최대치를 나타냈다. FR-IR 분석에 의하면 NH2의 NH3 bending mode가 1607cm-1, 1575cm-1에서 나타났으며 SiOH의 SiO band는 960cm-1에서 나타났다. XPS를 통해서는 N ls와 Si 2p의 존재를 확인할 수 있었다. 표면처리된 유리섬유와 matrix인 nylon 6를 이용해 단섬유내장시편을 만들어 fragmentation test를 한 결과 계면결합강도는 약 5분의 처리시간과 1%(wt%)의 농도에서 최대값을 보였다.

• Journal of the Korean Chemical Society
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• v.63 no.5
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• pp.327-334
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• 2019

Inhibition effects of cysteine(Cys), methionine(Met), and histidine(His) on the corrosion of cobalt were investigated in deaerated 0.5 M HCl and 0.5 M $H_2SO_4$ solution. All the inhibition efficiency (IE) in the amino acids for the cobalt corrosion depended on the mixed inhibition. However, IE in the solution of $H_2SO_4$ depended more on the anodic and in the solution of HCl on the cathodic inhibition. Amino acid adsorption process on cobalt surface in the solution can be explained by modified Langmuir isotherm. The molecules of histidine dissolved in both of the solution were physically adsorbed due to the electrostatic interaction between the surface of {$Co-Cl^{-{\delta}}$} and the {$-NH_3{^+}$} or {$-NH^+=$} of His. However the other cases of adsorption in this investigation can be explained by chemical adsorption between the empty d-orbital of Co and the lone pair of electron in S-atom in Cys and Met.

• Applied Chemistry for Engineering
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• v.32 no.3
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• pp.283-289
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• 2021

Adsorption characteristics of carbol fuchsin (CF) dye by coal-based activated carbon (CAC) were investigated using pH, initial concentration, temperature and contact time as adsorption variables. CF dissociates in water to have a cation, NH₂⁺, which is bonded to the negatively charged surface of the activated carbon in the basic region by electrostatic attraction. Under the optimum condition of pH 11, 96.6% of the initial concentration was adsorbed. Isothermal adsorption behavior was analyzed using Langmuir, Freundlich, Temkin and Dubinin-Radushkevich models. Langmuir's equation was the best fit for the experimental results. Therefore, the adsorption mechanism was expected to be adsorbed as a monolayer on the surface of activated carbon with a uniform energy distribution. From the evaluated Langmuir's dimensionless separation coefficients (R_L = 0.503~0.672), it was found that CF can be effectively treated by activated carbon. The adsorption energies determined by Temkin and Dubinin-Radushkevich models were E = 15.31~7.12 J/mol and B = 0.223~0.365 kJ/mol, respectively. Therefore, the adsorption process was physical (E < 20 J/mol, B < 8 kJ/mol). The experimental result of adsorption kinetics fit better the pseudo second order model. In the adsorption reaction of CF dye to CAC, the negative free energy change increased as the temperature increased. It was found that the spontaneity also increased with increasing temperature. The positive enthalpy change (40.09 kJ/mol) indicated an endothermic reaction.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.12
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• pp.2149-2161
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• 2000

Nonliving Absidia coerulea and Thraustochitrium sp. were used as biosorbents to remove lead and cobalt that are one of representative pollutant in wastewater and radioactive liquid waste. The optimum pH range for maximum lead and cobalt removal was increased 6.5~11.4 and 8.6~12.0 for Absidia coerulea and 4.2~10.5 and 8.9~11.6 for Thraustochitrium sp. to compared to biosorbent-free control, pH of 8.4~11.2 and 10.5~11.5, respectively. With 1 g biosorbent/L at initial solution pH 5.0. Absidia coerulea and Thraustochitrium sp. took up lead from aqueous solutions to the extent of 104 and 125 mg/g biomass, respectively, whereas Absidia coerulea and Thraustochitrium sp. at initial pH 6.0 took up only 2 and 20 mg/g biomass of cobalt, respectively. For initial 500 mg Pb/L at initial pH 5.0. optimum amount of biosorbent for maximum lead uptake was 0.2 g/L for Absidia coerulea and Thraustochitrium sp., whereas optimum 3.0 g biosorbent/L was needed for initial 200 mg Co/L at initial pH 6.0. Absidia coerulea and Thraustochitrium sp. had higher adsorption capacity for lead than that of cobalt.

• Applied Chemistry for Engineering
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• v.30 no.4
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• pp.460-465
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• 2019

In this study, the optimization of active materials and the preparation of particulate adsorbents for the application of metal oxide-based adsorbents for the treatment of $H_2S$, an air pollutant and odorant, occurred in various industrial facilities were investigated. The adsorbents were prepared by using $TiO_2$, which has a high physicochemical stability and relatively high specific surface area among metal oxides and also by different kinds and contents of active materials. The correlation between the physicochemical property and adsorption performance of the adsorbents confirmed that the adsorbent containing KI, which is a typical alkali metal among the active metals, showed the highest adsorption performance. The relationship between the contents and the adsorption performance was non-proportional, but a volcano plot. From XRD, SEM and BET analyses, it was confirmed that the active material was exposed to the surface above a certain amount and also the adsorption performance was the best when the specific surface area and pore volume were $40{\sim}100m^2/g$ and $0.1{\sim}0.3cm^3/g$, respectively. For practical application, the adsorbent was granulated or coated on a ceramic support. It was also confirmed that the adsorbent showed high adsorption performance when the adsorbent was coated on the ceramic rather than that of the granulated support.