• Journal of Microbiology and Biotechnology
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• v.27 no.6
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• pp.1138-1149
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• 2017

The use of microalgal biomass is an interesting technology for the removal of heavy metals from aqueous solutions owing to its high metal-binding capacity, but the interactions with bacteria as a strategy for the removal of toxic metals have been poorly studied. The goal of the current research was to investigate the potential of Burkholderia tropica co-immobilized with Chlorella sp. in polyurethane discs for the biosorption of Hg(II) from aqueous solutions and to evaluate the influence of different Hg(II) concentrations (0.041, 1.0, and 10 mg/l) and their exposure to different contact times corresponding to intervals of 1, 2, 4, 8, 16, and 32 h. As expected, microalgal bacterial biomass adhered and grew to form a biofilm on the support. The biosorption data followed pseudo-second-order kinetics, and the adsorption equilibrium was well described by either Langmuir or Freundlich adsorption isotherm, reaching equilibrium from 1 h. In both bacterial and microalgal immobilization systems in the co-immobilization of Chlorella sp. and B. tropica to different concentrations of Hg(II), the kinetics of biosorption of Hg(II) was significantly higher before 60 min of contact time. The highest percentage of biosorption of Hg(II) achieved in the co-immobilization system was 95% at pH 6.4, at 3.6 g of biosorbent, $30{\pm}1^{\circ}C$, and a mercury concentration of 1 mg/l before 60 min of contact time. This study showed that co-immobilization with B. tropica has synergistic effects on biosorption of Hg(II) ions and merits consideration in the design of future strategies for the removal of toxic metals.

• Korean Journal of Environmental Agriculture
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• v.26 no.2
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• pp.124-130
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• 2007

Excess application of paper mill sludge (PMS) in field can limit phosphorus uptake by crops because aluminum presented in the sludge can fix or adsorb available phosphorus which is necessary for crop growth. To investigate phosphorus (P) adsorption characteristics of PMS, we examined P adsorption maximum $(X_m)$ using Langmuir isotherm and P adsorption energy constant $(K_f)$ using Freundlich isotherm for PMS without alum, PMS with alum, and composted PMS with alum through a laboratory incubation test. The maximum P adsorption capacities were 800 ${\mu}g\;g^{-1}$ in soil, 47 $mg\;g^{-1}$ in PMS without alum and 61 $mg\;g^{-1}$ in PMS with alum. P adsorption capacity with alum treatment for PMS increased by 30%. That of PMS compost was 68 $mg\;g^{-1}$ and showed that composting increases 11% of P adsorption. Freundlich constant $K_f$ was 22 in check soil, while $K_f$ values in PMS without alum and in PMS with alum were 398 and 426, respectively. After composting, $K_f$ value of PMS compost significantly increased as 1,819. In conclusions, p adsorption capacity for PMS were increased by alum treatment or composting and therefore excess or continuous land application of alum-amended or composted PMS can limit P uptake for crops by reducing available P in sell.

• Journal of the Korean Chemical Society
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• v.54 no.1
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• pp.110-114
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• 2010

The equilibrium of adsorption of basics dyes RB 5 and BG 4 from a single dyes in the mixtures on the sodium-exchanged clay of the Maghnia (Algeria) was studied. The maximum adsorption capacities of BR5 and BG4 in single dyes were 465.13 and 469.90 mg/g respectively. In the simultaneous adsorption of BR5 and BG4 from mixture solutions, three different initials concentrations ratios R (R=$C_{(BR5)}/C_{(BG4)}$) were tested: 2.5/1, 1/1 and 1/2.5 using ADMI method. The isotherms adsorptions of dyes from the mixtures are characteristics of competition phenomenon. A very strong interaction between BR5 and BG4 for the active sites of adsorption of surface of clay is obtained for R = 1/1. The ratio R' (R'=$Qe_{(mixture)}/Qe_{(single)}$) of the adsorption capacity of BR5 and BG4 in the mixture were reduced by factor of 0.86, 0.74 and 0.84 for the initials concentrations ratios R (R=$C_{(BR5)}/C_{(BG4)}$) of 2.5/1, 1/1 and 1/2.5 respectively. The variation of the ratio of the adsorption capacity R‘ of BR5 and BG4 in the mixture solutions with initial concentration ratios R indicates that BR5 dye is slightly favourable in the competition adsorption than BG4. Langmuir and Freundlich models fit very well with adsorption behaviour of single dyes as well as the dyes in mixture solutions.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.8
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• pp.566-573
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• 2012

This study examined the removal rate of heavy metals from synthetic control water using red mud and lime stone. Overall, the percent of absorption obtained in this study for the red mud treatment was 94.0% ($Pb^{2+}$), 67.1% ($As^{3+}$), 37.5% ($Cu^{2+}$), and 36.6% ($Cr^{6+}$), while that of lime stone was $Pb^{2+}$ (30.8%), $Cu^{2+}$ (16.5%), $Cr^{6+}$ (11.5%), and $As^{3+}$ (8.9%). The kinetic data presented that the slow course of adsorption follows the Pseudo first and second order models, the equilibriuim adsorption of $Cr^{6+}$ and $Pb^{2+}$ obeys Freundlich isotherm model, while the adsorption of $Cu^{2+}$ obeys only Langmuir model. The results also showed that adsorption rate slightly increased with increasing pH from 5 to 9. Interestingly, this trend is similar to results obtained as function of loading amount of red mud. Meanwhile, an unit adsorption rate was slightly decreased. For lime stone, it did not much change in adsorption as function of treatment amount. Consequently, it was concluded that the absorbents can be successfully used the removal of the heavy metals from the aqueous solutions.

• Journal of the Korean GEO-environmental Society
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• v.13 no.5
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• pp.35-40
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• 2012

In this study, adsorption characteristics of expanded graphite (EG) were investigated by a series of batch adsorption tests using p-Xylene as a model volatile organic compounds (VOCs). After acid treatment, graphite were expanded at various temperature from $600^{\circ}C$ to $1000^{\circ}C$ for one minute. The optimal temperature was $800^{\circ}C$, where the expansion ratio reached 195 times of original volume. The BET specific surface area of EG was $92.4m^2/g$, which was only 1/10 of granular activated carbon (GAC), however the adsorption of p-Xylene by EG was almost completed within 5 minutes while that of GAC continued for 7 days because the majority of pores of EG was consisted with meso- and macro-pores. According to the Langmuir isotherm analysis, the maximum specific adsorption of p-Xylene onto EG was 24.0 mg/L with the adsorption constant of 7.94. In conclusion, the adsorption capacity of EG was much less than that of GAC due to the significantly lower specific surface area, but the first order kinetic constant was more than 500 times larger than GAC. Overall, EG might be effective where the fast adsorption is required.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.3
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• pp.112-117
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• 2017

Ion exchange fiber, PADD was synthesized by the reaction between PAN based acrylic fiber and DETA with $AlCl_3{\cdot}6H_2O$, and was analyzed by FT-IR and SEM to investigate its characteristics. The experimental results of Cr(VI) removal by PADD were better fitted with Langmuir adsorption isotherm, and the maximum uptake value ($Q_{max}$) was calculated to be 6.93 mmol/g. The kinetic data can be well described by Lagergen pseudo-second order rate model. The Cr(VI) adsorption capacity of PADD was 4.11 mmol/g at pH 2, which shows the effect of pH changes on the removal of Cr(VI). The adsorption selectivity of Cr(VI) was higher than phosphate and As(V). Total ion exchange capacity of PADD was 4.70 mmol/g, which was measured by acid-base back titration.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.13 no.3
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• pp.171-180
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• 2015

This study was performed on the removal of Cs, one of the main high- radioactive nuclides contained in the high-radioactive seawater waste (HSW), by adsorption with IE911 (crystalline silicotitanate type). For the effective removal of Cs and the minimization of secondary solid waste generation, adsorption of Cs by IE911 (hereafter denoted as IE911-Cs) was effective to carry out in the m/V (ratio of absorbent weight to solution volume) ratio of 2.5 g/L, and the adsorption time of 1 hour. In these conditions, Cs and Sr were adsorbed about 99% and less than 5%, respectively. IE911-Cs could be also expressed as a Langmuir isotherm and a pseudo-second order rate equation. The adsorption rate constants (k₂) were decreased with increasing initial Cs concentrations and particle sizes, and increased with increasing ratios of m/V, solution temperatures and agitation speeds. The activation energy of IE911-Cs was about 79.9 kJ/mol. It was suggested that IE911-Cs was dominated by a chemical adsorption having a strong bonding form. From the negative values of Gibbs free energy and enthalpy, it was indicated that the reaction of IE911-Cs was a forward, exothermic and relatively active at lower temperatures. Additionally, the negative entropy values were seen that the adsorbed Cs was evenly distributed on the IE911.

• 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.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.3
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• pp.162-166
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• 2011

Phosphorous contaminated in the effluent from sewage treatment plants can cause the eutrophication in surface water bodies. In this study, a powder of titanium oxysulfate-sulfuric acid made of ion-exchange materials was immobilized in an alginate gel and this material was examined to evaluate its phosphorous removal efficiency. Equilibrium and kinetic studies were carried out to quantify the adsorption capacity and time dependent removal rate of phosphorous. Adsorption isotherms and kinetic parameters were obtained for the entrapped titanium beads with three different methods. Equilibrium data were analyzed using Langmuir adsorption isotherm model and found to be well fitted to the model. The maximum adsorption capacity for phosphorous by the titanium bead synthesized with the solution method was 92.26 mg/g. Kinetic data followed a pseudo-second-order kinetic model. Due to the low production cost and high adsorption capacity, the titanium bead synthesized by the solution method has a potential to be utilized for the cost-effective removal of phosphorous from wastewater.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.8
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• pp.930-937
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• 2007

Korean pine(Pinus densiflora) bark was evaluated for its adsorption capacity of Cu(II) ions from aqueous solution by running a series of batch experiments. Prior to the tests, the milled barks were treated with 1 N NaOH or 1 N HCl to examine the effect of surface modification. For comparison, untreated bark was tested under same condition. Within the tested pH range between 3 and 6, NaOH treatment increased Cu(II) adsorption capacity by $139\sim184%$, while HCl treatment decreased it by $37\sim42%$. Maximum copper ion uptake by bark was observed at pH $5\sim6$, but pH of solution was not a potent influence. A pseudo second-order kinetic model fitted well for the sorption of copper ion onto bark. For NaOH-treated bark, the calculated sorption capacity$(q_e)$ increased from 6.58 to 12.77 mg/g, while the equilibrium rate constant$(k_2)$ decreased from 0.284 to 0.014 g/mg/min as initial Cu(II) concentration doubled from 100 mg/L. A batch isotherm test using NaOH-treated bark showed that equilibrium sorption data were represented by both the Langmuir model and the Freundlich model. It was confirmed that carboxylic acid of bark was involved in the Cu(II) adsorption. For NaOH-treated bark, in particular, carboxylate ion produced by hydrolysis or saponification appeared to be a major functional roup responsible for the enhanced Cu(II) sorption.