• 한국환경과학회지
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• 제23권3호
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• pp.379-386
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• 2014

Adsorption and biodegradation performance of tetracycline antibiotic compounds such as ttetracycline (TC), oxytetracycline (OTC), minocycline (MNC), chlortetracycline (CTC), doxycycline (DXC), meclocycline (MCC), demeclocycline (DMC) on granular activated carbon (GAC) and anthracite-biofilter were evaluated in this study. Removal efficiency of seven tetracycline antibiotic compounds showed 54%~97% by GAC adsorption process (EBCT: 5~30 min). The orders of removal efficiency by GAC adsorption were tetracycline, demeclocycline, oxytetracycline, chlortetracycline, doxytetracycline, meclocycline and minocycline. Removal efficiencies of seven tetracycline antibiotic compounds showed 1%~61% by anthracite biofiltration process (EBCT: 5~30 min). The highest biodegradable tetracycline antibiotic compound was minocycline, and the worst biodegradable tetracycline antibiotic compounds were oxytetracycline and demeclocycline.

• 상하수도학회지
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• 제21권3호
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• pp.349-357
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• 2007

Reports of endocrine disrupting compounds (EDCs), pharmaceutically active compounds (PhACs), and personal care products (PCPs) have raised substantial concern in important potable drinking water quality issues. Our study investigates the removal of EDCs, PhACs, and PCPs of 10 compounds having different physico-chemical properties (e.g., molecular weight, and octanol-water partition coefficient ($K_{OW}$)) by nanofiltration (NF) membranes. The rejection of micropollutants by NF membranes ranged from 93.9% to 99.9% depending on solute characteristics. A batch adsorption experiments indicated that adsorption is an important mechanism for transport/removal of relatively hydrophobic compounds, and is related to the octanol-water partition coefficient values. The transport phenomenon associated with adsorption may also depend on solution water chemistry such as pH and ionic strength influencing the pKa value of compounds. In addition, it was visually seen that the retention was somewhat higher for the larger compounds based on their molecular weight. These results suggest that the NF membrane retains many organic compounds due to both hydrophobic adsorption and size exclusion mechanisms.

• Carbon letters
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• 제12권1호
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• pp.1-7
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• 2011

In the present study, the removal of Pb (II) ions on oxidized activated carbons (ACs) was investigated. ACs were derived from activation of indigenous cotton stalks waste with potassium hydroxide (KOH) in two-stage process. The KOH-ACs were subjected to liquid-phase oxidation with hot $HNO_3$ and one untreated sample was included for comparison. The obtained carbons were characterized by Fourier transform infrared (FTIR), slurry pH and $N_2$-adsorption at 77 K, respectively. Adsorption capacity of Pb (II) ions on the resultant carbons was determined by batch equilibrium experiments. The experimental results indicated that the oxidation with nitric acid was associated with a significant increase in mass of yield as well as a remarkable reduction in internal porosity as compared to the untreated carbon. The AC-800N revealed higher adsorption capacity than that of AC-800, although the former sample exhibited low surface area and micropore volume. It was observed that the adsorption capacity enhancement attributed to pore widening, the generation of oxygen functional groups and potassium containing compounds leading to cation-exchange on the carbon surface. These results show that the oxidized carbons represented prospective adsorbents for enhancing the removal of heavy metals from wastewater.

• 한국대기환경학회지
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• 제12권3호
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• pp.315-322
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• 1996

Recently, hospital acquired infections have an increase interest as a public problems, which are caused of indoor pollutants in hospital. Microorganisms, ethylene oxide, formaldehyde, and anesthetic gases are main hazardous pollutants in hospital. The possible pathways of the infection are a respiratory channel as well as a blood channel. The blood channel is concerned since these pollutants might be dissolved into the Ringer's solution. The objective of this research was to evaluate the removal efficiencies of adsorption trap for formaldehyde and microorganisms as indoor pollutants which permeated into the Ringer's solution. Dissolved formaldehyde in the solution was increased with the injection dose time. The amount of dissolved formaldehyde was 67.5 $\pm$ 9.5% in Ringer's solution when injection dose time was controlled about 7hrs. An adsorption trap was designed for preventing formaldehyde and microorganisms to be permeated into Ringer's solution. The adsorption trap was packed with 0.4g of active carbon (60/80 mesh) in a sterilized plastic tube (7.79 cm length, 0.46 cm i.d.) and both ends were packed with glass wool. Devised infusion set equipped with the adsorption trap showed 99.9% of removal efficiency for formaldehyde. Microorganism numbers detected on sterilized water for injection and 5% dextrose infusion used in the hospital were 2,695 $\times 10^3$ cells/l and 4,190 $\times 10^3$ cells/l, respectively. Removal efficiency by the adsorption trap was 92.3 $\pm$ 8.5% as for microorgnisms.

• Membrane and Water Treatment
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• 제14권3호
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• pp.121-128
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• 2023

This study introduces a NaOH/Zn-assisted hydrothermal method for the synthesis of zeolites derived from coal ash (CA). A zeolite/Zn adsorbent is successfully prepared by the activation of CA with NaOH and Zn; it is characterized by a high surface area and a negative surface charge.Methylene blue (MB) and methyl orange (MO) are selected as dye pollutants, and their adsorption onto the zeolite/Zn adsorbent is investigated. Results show the high adsorption capacities of MB and MO and that the negative surface charge facilitates electrostatic interactions between the adsorbates and adsorbents. The zeolite/Zn adsorbents shows the selective adsorption of positively charged dye MB via electrostatic interactions between the =NH+ group (positive dipole) and the oxygen functional group of the adsorbents (negative dipole). The selectivity for the positively charged dye is sufficiently high, with the removal efficiency reaching 99.41% within 10 min. By contrast, the negatively charged dye MO exhibits negligible absorption. These findings confirm the role of electrostatic interactions in the adsorption of MB, in addition to the effect of a large surface area. The results of this study are expected to facilitate the development of simple, eco-friendly, and cost-effective zeolite-based adsorptive composites from CA residuals for the selective removal of dye pollutants from CA waste.

• 한국물환경학회지
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• 제22권6호
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• pp.991-995
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• 2006

The layered double hydroxide with the insertion of chloride ions (LDH-Cl), which was synthesized by the co-precipitation method, was applied to investigate the fundamental aspects of the absorptive agent for phosphate removal from wastewater. The adsorption capacity was best described by the Langmuir-FreundIich isotherm, and the estimated isotherm parameters indicate that the LDH-CI capacity for the phosphate removal is much higher than that observed using a natural adsorbent material such iron oxide tailing. The kinetic experiment also showed that the LDH-Cl adsorption reaction rapidly at the adsorptive rate of 0.55 mg-P/g-LDH/min, implying that this adsorbent can be of use in the full-scale applications. The pH had a minimal effect on the LDH adsorption capacity in the range of 5 to 11, although the capacity dropped at the low pHs because of the change in LDH surface properties. Furthermore, other anions such as $Cl^-$ and $NO_3{^-}$ commonly found in the wastewater streams insignificantly affected the phosphate removal efficiencies, while $HCO_3{^-}$ ions had a negative effect on the LDH adsorption capacity due to its high selectivity. The phosphate removal experiment using the actual secondary effluent from a wastewater treatment plant showed the similar decrease in adsorption capacity, indicating that the bicarbonate ions in the wastewater were competing with phosphate for the adsorptive site in the surface of the LDH-Cl. Overall, the synthetic adsorbent material, LDH-Cl, can be a feasible alternative over other conventional chemical agents, since the LDH-Cl exhibits the high phosphate removal capacity with the low sensitivity to other environmental conditions.

• 한국환경과학회:학술대회논문집
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• 한국환경과학회 2019년도 정기학술대회 발표논문집
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• pp.134-134
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• 2019

Utilization of organic waste as a renewable energy source is promising for sustainability and mitigation of climate change. Pyrolysis converts organic waste to gas, oil, and biochar by incomplete biomass combustion. Biochar is widely used as a soil conditioner and adsorbent. Biochar adsorbs/desorbs metals and ions depending on the soil environment and condition to act as a nutrient buffer in soils. Biochar is also regarded as a carbon storage by fixation of organic carbon. Phosphorus (P) and nitrogen (N) are strictly controlled in many wastewater treatment plants because it causes eutrophication in water bodies. P and N is removed by biological and chemical methods in wastewater treatment plants and transferred to sludge for disposal. On the other hand, P is an irreplaceable essential element for all living organisms and its resource (phosphate rock) is estimated about 100 years of economical mining. Therefore, P and N recovery from waste and wastewater is a critical issue for sustainable human society. For the purpose, intensive researches have been carried out to remove and recover P and N from waste and wastewater. Previous studies have shown that biochars can adsorb and desorbed phosphates implying that biochars could be a complementary fertilizer. However, most of the conventional biochar have limited capacity to adsorb phosphates and nitrate. Recent studies have focused on biochar impregnated with metal salts to improve phosphates and nitrate adsorption by synthesizing biochars with novel structures and surface properties. Metal salts and metal oxides have been used for the surface modification of biochars. If P removal is the only concern, P adsorption kinetics and capacity are the only important factors. If both of P and N removal and the application of recovery are concerned, however, P and N desorption characteristics and bioavailability are also critical factors to be considered. Most of the researches on impregnated biochars have focused on P removal efficiency and kinetics. In this study, coffee waste is thermally treated to produce biochar and it was impregnated with Mg/Al to enhance phosphates and nitrate adsorption/desorption and P bioavailability to increase its value as a fertilizer. Kinetics of phosphates and nitrate adsorption/desorption and bioavailability analysis were carried out to estimate its potential as a P and N removal adsorbent in wasewater and a fertilizer in soil.

• 환경생물
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• 제41권4호
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• pp.370-385
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• 2023

수자원의 부영양화와 인위적인 수변환경 조성 및 기후 변화의 영향으로 인한 유해 남세균의 대발생의 빈도와 강도가 증가하고 있다. 유해 남세균은 시아노톡신 (Cyanotoxins)을 배출하여 수자원의 안전뿐 아니라 생태계에 악영향을 주기 때문에 국제적인 환경문제로 관심을 받고 있다. 특히, 독성이 강한 마이크로시스틴(microcystins, MCs)의 제거를 위한 연구가 가장 활발히 연구되어 왔으며 이를 위한 다양한 수처리 방법이 제안되고 있다. 본 논문에서는 기존에 보고된 마이크로시스틴 제거를 위한 기술 중 경제적, 효율적인 방안으로 평가받고 있는 흡착기술(adsorption)에 대하여 주안점을 두고 조사하였다. 활성탄(activated carbons)은 마이크로시스틴 제거를 위한 흡착소재로 가장 광범위하게 활용되고 있으며 우수한 마이크로시스틴 흡착성능이 보고되고 있다. 바이오차(biochar), 생체흡착소재(biosorbents)와 같은 활성탄을 대체하는 흡착소재의 활용 연구도 진행되고 있으나 활성탄에 비하여 그 효과가 미흡한 실정이다. 이러한 마이크로시스틴 흡착에는 흡착소재의 특성(기공 특성과 표면화학적 특성)과 환경인자(용액의 pH, 온도, 자연 유기물 및 이온성 물질)가 영향을 미치는 것으로 보고되고 있으며 이에 대한 고찰을 진행하였다. 또한, 보다 효과적인 제어를 위하여 용존 마이크로시스틴의 제거뿐 아니라 유해 남세균의 직접적인 제거를 위한 흡착기술의 활용 가능성도 확인하였다. 하지만, 마이크로시스틴의 제거를 위한 실질적인 흡착소재의 활용을 위해서는 실제 환경조건에서 적용과 환경적, 경제적인 관점에서의 최적화 연구가 필요하다고 판단된다. 본 논문은 체계적인 자료 조사 및 분석을 통하여 향후 마이크로시스틴의 제거를 위한 효과적인 흡착소재 및 적용방법의 개발 및 선별에 관한 통찰을 제시할 수 있을 것이다.

• 한국환경과학회지
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• 제8권2호
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• pp.205-209
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• 1999

Iron hydroxides are good adsorbents for uncomplexed metals, some metal-ligand complexes and many metal oxyanions. However, their adsorption properties of these precipitations are not fully exploited in wastewater treatment operations because of difficulties associated with their separation from the aqueous phase. This study describes experiments in which iron hydroxides were coated onto the surface of ordinary adsorbents(Sea sand) that are very resistant to acids, The coated adsorbents were used in adsorption of oxyanionic metals. The process was successful in removing some anions such as $SeO_3(-II)$ over a wide range of metal concentrations and sorption of oxyanionic metals increased with decreasing pH. Formation of two surface complexes for oxyanionic metals adsorption on iron hydroxides comprise (1) complexation of the free anion by a positively charged surface site, and (2) protonation of the adsorbed anion (or alternatively adsorption of a protonated form from solution) The coated adsorbents are inexpensive to prepare and could serve as the basis of a useful oxyanionic metal removal.

• 한국환경과학회지
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• 제25권3호
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• pp.395-403
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• 2016

This study examined the adsorption effect of aromatic pesticides by hollow fiber NF membrane on rejection and removal properties. Batch type adsorption test and hollow fiber NF membrane filtration were conducted with 5 different kinds of aromatic pesticides. 3 to 15 days were required to reach the equilibrium concentration and $0.3181{\sim}0.8094{\mu}g/cm^2$ were adsorbed to hollow fiber NF membrane. Since 5 hours of separation test were too short to keep steady state for permeate due to the repetition of sorption and desorption, longer times were required to evaluate the rejection performance of NF membrane. Sorption and desorption were confirmed by the separation test equipped with membrane and without membrane. Adsorption contribution of aromatic pesticides to hollow fiber membranes were shown to be ranged from 16.1% to 36.3% and indicated the difference considering sorption effect.