• Journal of the Korean Wood Science and Technology
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• v.51 no.5
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• pp.321-333
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• 2023

In this study, lignin, a lignocellulosic biomass, was chemically modified to produce polyethyleneimine-grafted lignin (PKL) with maximum hexavalent chromium [Cr(VI)] adsorption capacity. Changes in the physicochemical properties due to the cationization of lignin were confirmed through elemental analysis, Fourier transform infrared spectroscopy, and moisture stability evaluation. Alginate (Alg) beads containing PKL (Alg/PKL) were prepared by incorporating cationic lignin into the Alg matrix to apply the prepared PKL in a batch-type water treatment process. The optimal Alg/lignin mixing ratio was selected to increase the Cr(VI) adsorption capacity and minimize lignin elution from the aqueous system. The selected Alg/PKL beads exhibited an excellent Cr(VI) removal capacity of 478.98 mg/g. Isothermal adsorption and thermodynamic analysis revealed that the Cr(VI) removal behavior of the Alg/PKL beads was similar to that of heterogeneous chemical adsorption. In addition, the bulk adsorbent material in the form of beads exhibited adsorption behavior in three stages: surface adsorption, diffusion, and equilibrium.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.1
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• pp.19-25
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• 2017

In this study, a electrostatic filter which could be applicable to road environment was developed and evaluated in adsorption capacity. The evaluation were performance for removal by particle size and adsorption amount by pressure using ASERAE 52.1 and 52.2. The range of size for removal test was $0.3{\mu}m{\sim}10.0{\mu}m$ which had 12 steps. The filter showed 91.3% removal efficiency from $2.5{\mu}m$ and under the size, average 53.5% proportional to decreasing size value. The weight removal was 96.7% from 22.6 mmaq, initial pressure to 35 mmaq, end pressure with $715.9g/m^2$, the adsorption amount. The shape of isotherm was expressed as Langmuir's one. After washing saturated filter with dust to end pressure, the initial pressure and adsorption amount of the filter showed a light drop with no removal efficiency decline.

• Journal of Korean Society of Water and Wastewater
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• v.37 no.4
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• pp.177-186
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• 2023

Perfluorooctanoic acid(PFOA) was one of widely used per- and poly substances(PFAS) in the industrial field and its concentration in the surface and groundwater was found with relatively high concentration compared to other PFAS. Since various processes have been introduced to remove the PFOA, adsorption using GAC is well known as a useful and effective process in water and wastewater treatment. Surface modification for GAC was carried out using Cu and Fe to enhance the adsorption capacity and four different adsorbents, such as GAC-Cu, GAC-Fe, GAC-Cu(OH)₂, GAC-Fe(OH)₃ were prepared and compared with GAC. According to SEM-EDS, the increase of Cu or Fe was confirmed after surface modification and higher weight was observed for Cu and Fe hydroxide(GAC-Cu(OH)₂ and GAC-Fe(OH)₃, respectively). BET analysis showed that the surface modification reduced specific surface area and total pore volumes. The highest removal efficiency(71.4%) was obtained in GAC-Cu which is improved by 17.9% whereas the use of Fe showed lower removal efficiency compared to GAC. PFOA removal was decreased with increase of solution pH indicating electrostatic interaction governs at low pH and its effect was decreased when the point of zero charges(pzc) was negatively increased with an increase of pH. The enhanced removal of PFOA was clearly observed in solution pH 7, confirming the Cu in the surface of GAC plays a role on the PFOA adsorption. The maximum uptake was calculated as 257 and 345 ㎍/g for GAC and GAC-Cu using Langmuir isotherm. 40% and 80% of removal were accomplished within 1 h and 48 h. According to R², only the linear pseudo-second-order(pso) kinetic model showed 0.98 whereas the others obtained less than 0.870.

• Journal of Korean Society of Water and Wastewater
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• v.29 no.5
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• pp.565-573
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• 2015

The influencing factors to remove phosphate were evaluated by converter slag (CS). Experiments were performed by batch tests using different CS sizes and column test. Solutions were prepared at the different pH and concentrations. The maximum removal efficiency was obtained over 98% with the finest particle size, $CS_a$ within 2 hours in batch tests. The removal efficiency was increased in the order of decreasing size with same amount of CS for any pH of solutions. The adsorption data were well fitted to Freundlich isotherm. From the column experiment, the specific factors were revealed that the breakthrough removal capacity (BRC) $x_b/m_{cs}$, was decreased by increasing the influent concentration. The breakthrough time, tb was lasted shorter as increasing the influent concentration. The pH drop simultaneously led to lower BRC drop during the experimental hours. The relation between the breakthrough time and the BRC to influent concentration was shown in the logarithmic decrease. Results suggested that the large surface area of CS possessed a great potential for adsorptive phosphate removal. Consequently particle size and initial concentration played the major influencing factors in phosphate removal by converter slag.

• Journal of Environmental Science International
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• v.16 no.6
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• pp.671-675
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• 2007

The objective of this study was to clarify the characteristics of the removed micropollutant since the breakthrough of adsorption ability was occurred in biological activated carbon(BAC) process. The removal efficiency of DOC (Dissolved Organic Carbon) was 36 % in the breakthrough of BAC occurred by NOM (Natural Organic Matter). The most of removal DOC was found out the adsorbable and biodegradable DOC (A&BDOC). But it was not clear to remove by any mechanism because A&BDOC have simultaneously the adsorption of activated carbon and biodegradation by microorganism in BAC. The removal of bromophenol was examined with BAC and rapid sand filter, for investigation of DOC removal mechanism in the breakthrough of BAC. In this experiment, BAC filter has been operated for 20 months for the treatment of reservoir water. The BAC filter was already exhausted by NOM. Bromophenol, adsorbable and refractory matter, was completely removed by BAC filter. Therefore, it might be removed by the adsorption in BAC. Adsorption isotherms of bromophenol were compared to two BACs which was preloaded with 500 daltons and 3,000 daltons of NOM. BAC preloaded with 3,000 daltons of NOM was not decreased to the adsorbability of bromophenol but BAC preloaded with 500 daltons of NOM was greatly decreased to it. These result indicated that NOM of low molecular weight can be removed by adsorption after a long period of operation and the breakthrough by NOM in BAC. Therefore, micropollutants might be removed through adsorption by saturated BAC.

• Korean Chemical Engineering Research
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• v.55 no.5
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• pp.685-689
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• 2017

We studied the removal of zinc ions from synthetic brackish water by an adsorption method using natural Algerian Bentonite (NAB). The effect of the main physico chemical parameters-contact time, pH, temperature, ionic strength, clay weight and initial metal ion concentrations on the removal of $Zn^{+2}$-were investigated. The results showed that equilibrium was attained within 10 min of stirring time. The retention capacity of $Zn^{+2}$ increased with the increase of pH, the adsorbent dose and ionic strength. A modelization study showed that the adsorption follows Langmuir isotherm, while its kinetics was pseudo-second-order. Based on the results, it was concluded that NAB, which is natural and available, could be used as an alternative for the removal of zinc from saline aqueous solutions.

• Journal of environmental and Sanitary engineering
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• v.14 no.2
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• pp.40-45
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• 1999

This study deals with an investigation on low cost adsorbents locally available n dyeing wastewater treatment of color removal. Peat, bentonite, slag and fly ash were utilized for this study. Considering that low cost adsorbents contained in $SiO_2$, $Fe_2O_3$ and $Al_2O_3$ compositions, and coagulants were mainly used aluminate and ferrate in color removal. Color of dyeing wastewater was high removed in peat, berntonite and slag except for fly ash with passed time. It could be known that color removal of peat and slag were increased to pH 4, but was hardly changed with advancing to alkaline. Color intended to be high removed with increasing of agitation speed but to be almost slow after 150rpm. As a result on the experiment of Freundlich adsorption isotherms, adsorption intensity(l/n) appeared to be peat>fly ash>slag>bentonite and adsorption capacity(k) came out peat>bentonite>slag>fly ash. Therefore, if low cost adsorbents substituted for existing adsorbents, peat, bentonite and slag could look forward to an expected economical effect.

• Journal of Korean Society of Water and Wastewater
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• v.25 no.6
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• pp.917-922
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• 2011

Adsorption characteristics of boron on activated carbon was investigated in order to evaluate the use of activated carbon for the removal of boron in desalination processes using SWRO. Boron was removed ranging from 54~60% when the concentration of activated carbon was 1,000 mg/L in 6 hours under the initial boron concentration of 5 mg/L. The removal of boron increased by 20~22% with the increase of pH from 5 to 9. Organic matter had adverse effect on the adsorption of boron on activated carbon. Boron removal decreased by 10-12% when EDTA was added at 1 mg/L under 5 mg/L of boron and 200mg/L of activated carbon. In this results, activated carbon would be a good candidate for a pretreatment of desalination processes by SWRO from the view of mitigating the feed boron concentration to RO and meeting the effluent boron concentration without post-treatment after RO.

• Journal of Environmental Health Sciences
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• v.27 no.2
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• pp.138-144
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• 2001

This study was carried out to investigate characteristics and Pb(II) removal effect of natural clays in the batch mode test. The effect of parameters such as temperature, adsorption time and coexisting cations on the sorption ability and characteristics was investigated to find out whether the clays could be used as adsorbents. Several natural clays from domestic have been investigated to have high specific surface area and have minerals such as SiO$_2$ and $Al_2$O$_3$. As a result, removal effects of Pb(II) on clays were reached at equilibrium in aqueous solutions by stirring about 20 minutes. The removal effect of Pb(II) was best for Kang Jin clay than other clays in terms of fixed time. Adsorption efficiency was not influenced by the possibility of continuous treatment system of wastewater which contain heavy metals by using natural clays from domestic.

• Journal of Environmental Health Sciences
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• v.24 no.1
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• pp.98-103
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• 1998

A study on the removal of mercury and lead by microorganisms, Saccharomyces cerevisiae and Aureobasidium pullulans, was performed, in which the comparison of adsorption model between these two heavy metals was done. The amounts of mercury removed were more than those of lead in both microorganisms. In case of mercury, the adsorption isotherm of S. cerevisiae was accorded with Langmuir model but A. pullulans was followed to Freundlich model. In the case of lead, however, the adsorption isotherm had opposite results. The adsorption rate of mercury to S. cerevisiae was faster than that of A. pullulans, but in the case of lead, it revealed contrary results. It seems, therefore, that the type of microorganisms used as biosorbents should be selected differently with the type of heavy metals removed for applying these to real adsorption process.