• Membrane and Water Treatment
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• v.12 no.1
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• pp.23-35
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• 2021

A POM-membrane was fabricated by immobilizing a keggin type polyoxometalate (POM) H5PV2Mo10O40 onto the surface of microporous flat-sheet polymeric polyvinylidene fluoride (PVFD) membrane using a chemical deposition method. The POM-membrane was characterized by FT-IR, SEM and EDX to confirm existing of the POM onto the membrane surface. The POM-membrane was used to remove an anionic textile dye (Reactive Black 5 named as an RB5) from aqueous phases with a cross-flow membrane filtration and a batch adsorption system. The dye removal efficiency of the POM-membrane using the cross-flow membrane filtration system and the batch adsorption system was about 88% and 98%, respectively. The influence factors such as contact time, adsorbent dosage, pH, and initial dye concentration were investigated to understand the adsorption mechanism of the RB5 dye onto the POM-membrane. To find the best fitting isotherm model, Langmuir, Freundlich, BET and Harkins-Jura isotherm models were used to analyze the experimental data. The isotherm analysis showed that the Langmuir isotherm model was found to the best fit for the adsorption data (R2 = 0.9982, qmax = 24.87 mg/g). Also, adsorption kinetic models showed the pseudo second order kinetic model was found the best model to fit the experimental data (R2 = 0.9989, q = 8.29 mg/g, C0 = 15 ppm). Moreover, after four times regeneration with HNO3 acid, the POM-membrane showed high regenerability without losing dye adsorption capacity.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.4
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• pp.246-252
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• 2015

In steel factory, hot roller cleaning process produces a lot of iron oxide particles called as mill scale. Major components of these particles are wustite (FeO), magnetite ($Fe_3O_4$), and hematite ($Fe_2O_3$). In this study, we tried to produce pure magnetite from the mill scale because of the largest phosphate adsorption capacity of the magnetite. The mill scale was treated with acid (HCl+$H_2O_2$), base (NaOH), and acid-base ($H_2SO_4$+NaOH). Batch adsorption tests showed the acid and/or base treatment could increase the phosphate adsorption capacity of the iron oxides from 0.28 to over 3.11 mgP/g. Magnetite, which could be obtained by acid and base treatment of the mill scale, showed the best adsorption capacity. From the kinetic analysis, both Freundlich and Langmuir isotherm well described the phosphate adsorption behavior of the magnetite. In Langmuir model, maximum phosphate adsorption capacity was found to be 5.1 mgP/g at $20^{\circ}C$.

• Applied Chemistry for Engineering
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• v.25 no.6
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• pp.632-638
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• 2014

Batch adsorption studies including equilibrium, kinetics and thermodynamic parameters for the adsorption of new fuchsin dye using granular activated carbon were investigated with varying the operating variables such as initial concentration, contact time and temperature. Equilibrium adsorption data were fitted into Langmuir, Freundlich, Dubinin-Radushkevich and Temkin isotherms. Adsorption equilibrium was mostly well described by Langmuir Isotherm. From the estimated separation factor of Langmuir ($R_L$ = 0.023), and Freundlich (1/n = 0.198), this process could be employed as an effective treatment for the adsorption of new fuchsin dye. Also based on the adsorption energy (E = 0.002 kJ/mol) from Dubinin-Radushkevich isotherm and the adsorption heat constant (B = 1.920 J/mol) from Temkin isotherm, this adsorption is physical adsorption. From kinetic experiments, the adsorption reaction processes were confirmed following the pseudo second order model with good correlation. The intraparticle diffusion was a rate controlling step. Thermodynamic parameters including changes of free energy, enthalpy, and entropy were also calculated to predict the nature of adsorption. The change of enthalpy (92.49 kJ/mol) and activation energy (11.79 kJ/mol) indicated the endothermic nature of adsorption processes. The change of entropy (313.7 J/mol K) showed an increasing disorder in the adsorption process. The change of free energy found that the spontaneity of process increased with increasing the adsorption temperature.

• Applied Chemistry for Engineering
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• v.25 no.4
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• pp.430-436
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• 2014

Allura Red (AR) is a water-soluble harmful tar-based food colorant (FD & C Red 40). Batch adsorption studies were performed for the removal of AR using bituminous coal based granular activated carbon as adsorbent by varying the operation parameters such as adsorbent dosage, initial concentration, contact time and temperature. Experimental equilibrium adsorption data were analyzed by Langmuir, Freundlich and Temkin isotherms. The equilibrium process was described well by Freundlich isotherm. From determined separation factor ($R_L$), adsorption of AR by granular activated carbon could be employed as effective treatment method. Temkin parameter, B was determined to 1.62~3.288 J/mol indicating a physical adsorption process. By estimation of adsorption rate experimental data, the value of intraparticle diffusion rate constant ($k_m$) increased with the increasing adsorption temperature. The adsorption process were found to confirm to the pseudo second order model with good correlation. Thermodynamic parameters like change of free energy, enthalpy, and entropy were also calculated to predict the nature adsorption in the temperature range of 298~318 K. The negative Gibbs free energy change (${\Delta}G$ = -2.16~-6.55 kJ/mol) and the positive enthalpy change (${\Delta}H$ = + 23.29 kJ/mol) indicated the spontaneous and endothermic nature of the adsorption process, respectively.

• Clean Technology
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• v.20 no.1
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• pp.35-41
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• 2014

Batch adsorption studies were carried out for equilibrium, kinetic and thermodynamic parameters for quinoline yellow adsorption by granular activated carbon ($8{\times}30mesh$, $1,578m^2/g$) with varying the operating variables like initial concentration, contact time and temperature. Equilibrium adsorption data were fitted into Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherms. From estimated Langmuir constant ($R_L=0.0730{\sim}0.0854$), Freundlich constant (1/n = 0.2077~0.2268), this process could be employed as effective treatment for removal of quinoline yellow. From calculated Temkin constant (B = 15.759~21.014 J/mol) and Dubinin-Radushkevich constant (E = 1.0508~1.1514 kJ/mol), this adsorption process is physical adsorption. From kinetic experiments, the adsorption process were found to confirm to the pseudo second order model with $r^2$ > 0.99 for all concentrations and temperatures. Thermodynamic parameters like activation energy, change of free energy, enthalpy, and entropy were also calculated to predict the nature adsorption. The activation energy value (+35.137 kJ/mol) and enthalpy change (35.03 kJ/mol) indicated endothermic nature of the adsorption process. Entropy change (+134.38 J/mol K) showed that increasing disorder in process. Free energy change found that the spontaneity of process increased with increasing adsorption temperature.

• Korean Journal of Environmental Agriculture
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• v.38 no.2
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• pp.83-88
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• 2019

BACKGROUND: In recent years, studies on microplastics have focused on their decomposition in the ocean. However, no studies have been reported on the interaction between microplastics and metal ions in aqueous solutions. Therefore, this study was conducted to evaluate the adsorption capacity of cadmium(Cd) by polypropylene (PP) in aqueous solution. METHODS AND RESULTS: Cadmium adsorption characteristics of PP in aqueous solution were evaluated through various conditions including initial Cd concentration(1.25-25 mg/L), contact time(0.5-24 h), initial pH(2-6) and temperature($20-50^{\circ}C$). Cadmium adsorption fit on PP was well described by Freundlich isotherm model with adsorption capacity(K) of 0.028. The adsorption amount of Cd by PP increased with increasing contact time, indicating that adsorption of PP by Cd was dominantly influenced by contact time. Especially, the removal efficiency of Cd by PP was highest at high temperature. However, the surface functional groups of PP before and after adsorption of Cd were similar, suggesting that adsorption of Cd by PP is not related to surface functional groups. CONCLUSION: Our study suggests that PP affects the behavior of Cd in aqueous solution. However, in order to clarify the specific relationship between microplastics and metal ions, mechanism research should be carried out.

• Journal of the Korean GEO-environmental Society
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• v.7 no.1
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• pp.41-53
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• 2006

In this study, estimation of nonlinear adsorption isotherms(Langmuir & Freundlich adsorption isotherm) and advection-dispersion model parameters was conducted using genetic algorithm(GA) for Zn and Cd adsorption. Estimated parameters of nonlinear adsorption isotherms, which were obtained from the optimization process using genetic algorithm(GA), are nearly same with the parameters obtained from a linearization process of the nonlinear isotherms. Estimated effective diffusion coefficients, which were obtained from a finite element analysis of the advection-dispersion model and an optimization procedure using the genetic algorithm, for the metals were approximately in the order of $10^{-7}cm^2/s$ which could be obtained based on the linear distribution coefficient. The effective diffusion coefficients based on the nonlinear retardation factors were in the range of $10^{-6}{\sim}10^{-5}cm^2/s$. As a result, the correlation coefficient obtained between the measured and calculated concentration was over 0.9 which means that the genetic algorithm should be successfully applied to estimate the unknown parameters of the nonlinear adsorption isotherms and advection-dispersion model.

• Korean Chemical Engineering Research
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• v.55 no.6
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• pp.798-806
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• 2017

A activated carbon (WCAC, waste citrus activated carbon) prepared from an agricultural waste citrus peel material generated in Jeju was utilized for the removal of dimetridazole (DMZ) antibiotics in aqueous solution. The adsorption of DMZ on WCAC was investigated with the change of various parameters such as contact time, dosage of WCAC, particle size of WCAC, temperature, pH, and DMZ concentration. The DMZ adsorption capacity increased with increasing temperature and decreasing particle size. Also it was decreased at less than pH 4 but sustained almost constantly at pH 4 or greater. Isotherm parameters were determined from the Langmuir, Freundlich, Redlich-Peterson and Duinin-Radushkevich (D-R) isotherm models. The isotherm data were best described by the Redlich-Peterson isotherm model. And the adsorption kinetics can be successfully fitted to the pseudo-second-order kinetic model. The results of the intra-particle diffusion model suggested that film diffusion and intra-particle diffusion were occurred simultaneously during the adsorption process. Meanwhile, the thermodynamic parameters indicated that the adsorption reaction of DMZ on WCAC was an endothermic and spontaneous process. The experimental results showed that WCAC is a promising and cheap adsorbent for the removal of DMZ antibiotics.

• Nuclear Engineering and Technology
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• v.16 no.2
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• pp.64-69
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• 1984

With regard to the radioactive waste disposal, adsorption properties and migration rates have been evaluated for Cs-137 and Sr-90 with the domestic clay sampled from Cnyang, Sanchong and Mooan. Sorption coefficients (Ksorp) were determined by batch experiments. The measured values of Ksorp were ranged from 8000 to 17,000 ml/gr for Cs-137 of 0.1$\mu$Ci/ml, and from 10,000 to 15,000m1/gr for Sr-90 of 0.l$\mu$Ci/ml. Remarkably, Mooan clay showed lower values of Ksorp than those of the others. This could be explained by the poor soprtion capacity of the quartz found only in the Mooan clay. For the quantitative analysis, sorption isotherm equations of Freundlich type were made with the obtained values of Ksorp. $C_{R}$=18.0 $C_{A}$$^{0.74}$ : Cs-137, $C_{R}$=0.84 $C_{A}$$^{0.45}$ : Sr-90. By introducing the BOX model combined with the above relationships, simulation of underground nuclide movement was carried out. The results showed that the domestic clays could be the effective backfill material for repositories.itories.ies.

• 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.