• Journal of Korean Society of Environmental Engineers
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• v.33 no.11
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• pp.804-811
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• 2011

The aim of this study is to evaluate the applicability of adsorption models for understanding adsorption properties of adsorbents. For this study, the adsorption charateristics of $NO_3^-$ by commercial anion exchange resin, PA-308, were investigated in bach process. The adsorption kinetic data for $NO_3^-$ by anion exchange resin showed two stage process comprising a fast initial adsorption process and a slower second adsorption process. Both the pseudo-first-order kinetic model and the pseudo-second-order kinetic model could not be used to predict the adsorption kinetics of $NO_3^-$ onto anion exchange resin for the entire sorption period. Only the fast initial portion ($t{\leq}20min$) of adsorption kinetics was found to follow pseudo-first-order kinetic model and controlled mainly by external diffusion that is very fast and high, whereas, the slower second portion (t > 20 min) of adsorption kinetics seems to be controlled by a second-order chemical reaction and by intraparticle diffusion.

• Journal of the Korean Chemical Society
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• v.54 no.1
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• pp.125-130
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• 2010

In the present work, we have investigated the adsorption efficiency of carbon/iron oxide nanocomposite towards removal of hazardous brilliant green (BG) from aqueous solutions. Carbon/iron oxide nanocomposite was prepared by chemical precipitation and thermal treatment of carbon with ferric nitrate at $750^{\circ}C$. The resulting material was thoroughly characterized by TEM, XRD and TGA. The adsorption studies of BG onto nanocomposite were performed using kinetic and thermodynamic parameters. The adsorption kinetics shows that pseudo-second-order rate equation was fitted better than pseudo-first-order rate equation. The experimental data were analyzed by the Langmuir and Freundlich adsorption isotherms. Equilibrium data was fitted well to the Langmuir model with maximum monolayer adsorption capacity of 64.1 mg/g. The thermodynamic parameters were also deduced for the adsorption of BG onto nanocomposite and the adsorption was found to be spontaneous and endothermic.

• Korean Chemical Engineering Research
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• v.57 no.2
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• pp.219-224
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• 2019

In this study, the adsorption characteristics of cephalomannine on commercial adsorbent Sylopute were investigated using different parameters such as adsorption temperature, time, and initial cephalomannine concentration for the efficient separation of Taxus chinensis-derived cephalomannine by adsorption process. The Temkin isotherm model showed good fit to the equilibrium adsorption data. The adsorption capacity decreased with increasing temperature and the adsorption of cephalomannine onto Sylopute was physical in nature. Adsorption kinetic data fitted well with pseudo-second-order kinetic mode. According to the intraparticle diffusion model, film diffusion and intraparticle diffusion did not play a key role in the entire adsorption process. The process of cephalomannine adsorption onto Sylopute was exothermic and spontaneous. In addition, the isosteric heat of adsorption was constant even with variation in surface loading indicating homogeneous surface coverage.

• Korean Journal of Soil Science and Fertilizer
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• v.33 no.1
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• pp.32-39
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• 2000

To investigate the adsorption-desorption reaction of Cd by sewage sludge, the adsorption of Cd from $Cd(NO_3)_2$ solutions of concentrations ranging from 5 to $50{\mu}g\;Cd\;mL^{-1}$ by sewage sludge was examined for reaction periods up to 48 hours. The amount of Cd adsorbed as a function of time was measured. The adsorption between Cd in solution and the solid phase could be described by two stages. The initial adsorption of Cd was very rapid, that is, approximately 95% of the added Cd was removed from solution within the first 30 minutes. Further, the greater the concentration of Cd added, the greater was the amount of Cd adsorbed. After the rapid initial decrease of Cd, a slower decline in the Cd concentration resulted which followed first order reversible kinetics. The equilibrium concentrations for the reactions, as well as the time period for the equilibrium reactions were dependent on the initial Cd concentrations. If equilibrium is reached, the amount of Cd remaining in solution is greater when the amount adsorbed is higher, although the percentage of Cd in solution is constant relative to the initial concentration of Cd. Some of the adsorbed Cd was released back to solution since the concentration of Cd after 48 hours was higher than the equilibrium concentration of Cd. However, despite the increased amount of Cd measured, the overall net reaction was a significant adsorption of Cd from solution by sewage sludge.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.3
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• pp.220-225
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• 2013

The adsorption characteristics of phenol by the powdered activated carbon (PAC) were investigated by series of batch experiments. The pseudo-second-order model described the adsorption kinetics adequately with correlation coefficients over 0.999, indicating chemical adsorption as the rate-limiting step. The kinetic rate constants were from 0.55 to 19.81 mg $mg^{-1}min^{-1}$. The adsorption isotherm followed the Langmuir isotherm, indicating the homogeneous mono-layer adsorption onto the surface of the adsorbent. The values of activation energy, enthalpy and entropy were 17.44 kJ $mol^{-1}$, -8.26 kJ $mol^{-1}$ and -18.94 J $mol^{-1}K^{-1}$, respectively. The Gibbs free energy was in the range of -2.89~-2.14 kJ $mol^{-1}$. The results show that the phenol adsorption is physical, spontaneous and exothermic reaction.

• Journal of the Korean Chemical Society
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• v.54 no.5
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• pp.603-610
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• 2010

The potential feasibility of Maghnia clay as adsorbent to remove three cationic dyes (methylene blue (MB), neutral red (NR) and malachite green oxalates (MG)) from aqueous solution was investigated at various operating parameters such as contact time, pH, initial dye concentration and adsorbent dose. Optimum pH values for dyes adsorption were 6 for NR and 7 for MB and MG, respectively. Maximum adsorption of dyes, i.e. $\geq$ 90% has been achieved in aqueous solutions in 60 minutes. The adsorption of dyes followed the pseudo-second-order rate equation.

• Applied Chemistry for Engineering
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• v.3 no.4
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• pp.649-656
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• 1992

The synthesis of epichlorohydrin was carried out by the epoxidation of allyl chloride with tert-butyl hydroperoxide(TBHP) over silica supported molybdenum catalyst. Kinetic study was performed at $60-80^{\circ}C$ and 10 atm with the molar ratio of TBHP/Allyl chloride between 0.01 and 0.1 in a batch reactor. The epoxidation of allyl chloride was inhibited by tert-butyl alcohol and kinetic data could be represented by Michaelis-Meten type rate equation. The reaction mechanism could be explained by the combination of reversible adsorption of TBHP and tert-butyl alcohol accompanied by reaction of allyl chloride with TBHP adsorbed on $Mo/SiO_2$ catalyst.

• Journal of the Mineralogical Society of Korea
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• v.21 no.4
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• pp.425-434
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• 2008

Arsenic contamination in soil and groundwater has recently been one of the most serious environmental concerns. This arsenic contamination can be originated from natural or anthropogenic sources. It has been well known that arsenic behavior in geo-environmental is controlled by various oxides or hydroxides, such as those of iron, manganese, and aluminum, and clay minerals. Among those, particularly, iron (oxy)hydroxides are the most effective scavengers for arsenic. For this reason, this study characterized arsenic adsorption of magnetite which is a kind of iron oxide in nature. The physicochemcial features of the magnetite were investigated to evaluate adsorption of arsenite [As(III)] and arsenate [As(V)] onto magnetite. In addition to experiments on adsorption equilibria, kinetic experiments were also conducted. The point of zero charge (PZC) and specific surface area of the laboratory-synthesized magnetite used as an arsenic adsorbent were measured 6.56 and $16.6\;g/m^2$, which values seem to be relatively smaller than those of the other iron (oxy)hydroxides. From the results of equilibria experiments, arsenite was much more adsorbed onto magnetite than arsenate, indicating the affinity of arsenite on magnetite is larger than arsenate. Arsenite and arsenate showed adsorption maxima at pHs 7 and 2, respectively. In particular, adsorption of arsenate decreased with increase in pH as a result of electrical repulsion caused by anionic arsenate and negatively-charged surface of magnetite. These results indicate that the surface charge of magnetite and the chemical speciation of arsenic should be considered as the most crucial factors in controlling arsenic. The results of kinetic experiments show that arsenate was adsorbed more quickly than arsenite and adsorption of arsenic was investigated to be mostly completed within the duration of 4 hours, regardless of chemical speciation of arsenic. When the results of kinetic experiments were fitted to a variety of kinetic models proposed so far, power function and elovich model were evaluated to be the most suitable ones which can simulate adsorption kinetics of two kinds of arsenic species onto magnetite.

• Analytical Science and Technology
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• v.12 no.6
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• pp.465-471
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• 1999

Chloromethylated polystyrene resins supported diethylenetriamine of linear and claw types have been prepared by the reaction of diethylenetriamine with chloromethylated polystyrene. The kinetics of adsorption of transition metal ions on polystyrene resins were measured by the limited-bath technique. This paper reports the results of the diffusion coefficients, entropies of activation, and free energies of activation. The ratedetermining step of the adsorption of transition metals on the resins is a process of diffusion through the particles.

• Korean Chemical Engineering Research
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• v.55 no.6
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• pp.874-880
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• 2017

In this study, we performed numerical simulation of the adsorptive desulfurization reactor for a 100 kW fuel cell. Using experimental results and the adsorption kinetics theory, the adsorption rate of sulfur in diesel was estimated and verified by numerical analysis. By analyzing the performance of desulfurization according to reactor size, the optimal reactor size was determined. By maximizing processed diesel amount, optimal diesel flow rate was determined. Regeneration process was also confirmed for the obtained optimal reactor size. The present work will be utilized to design a diesel desulfurization reactor for a fuel cell used in a ship by further process modeling and economic analysis.