• 한국환경보건학회지
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• 제45권6호
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• pp.561-568
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• 2019

Objectives: The most commonly detected heavy metals in rocks and soils, including Pb, Cd, Cu, Fe, Mn and As, are representative pollutants discharged from abandoned mines and have been listed as potential sources of contamination in drinking water. This study focused on increasing the removal efficiency of heavy metals from drinking water resources by surface modification of natural adsorbents to reduce potential health risks. Methods: Iron oxide coating and graft polymerization with zeolites and talc was conducted for bipolar surface modification to increase the combining capacity of heavy metals for their removal from water. The removal efficiency of heavy metals was measured before and after the surface modification. Results: The removal efficiency of Pb, Cu, and Cd by surface modified zeolite showed 100, 92, and 61.5%, respectively, increases compared to 64, 64, and 38% for non-modified zeolite. This implies that bipolar surface modified natural adsorbents have a good potential use in heavy metal removal. The more interesting finding is the removal increase for As, which has both cation and anion characteristics showing 27% removal efficiency where as non-modified zeolite showed only 2% removal. Conclusions: Zeolite is one of the most widely used adsorptive materials in water treatment processes and bipolar surface modification of zeolite increases its applicability in the removal of heavy metals, especially As.

• Advances in environmental research
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• 제4권1호
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• pp.49-68
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• 2015

Chemically activated and carbonized adsorbents were prepared from Moringa oleifera pod husks (MOP), characterized and evaluated for their ability to remove a common antibiotic - ofloxacin (OFX) from aqueous solution. The pulverized precursor was steeped in a saturated ammonium chloride solution for a day to give the chemically activated adsorbent (AMOP). A portion of AMOP was pyrolyzed in a muffle furnace at 623 K for 30 min to furnish its carbonized analogue (CMOP). The adsorbents showed favorable physicochemical attributes. The effects of operational parameters such as initial OFX solution pH and concentration, adsorbent dosage, temperature and contact time on OFX removal were investigated. At equilibrium, optimal removal efficiencies of 90.98% and 99.84% were achieved at solution pH 5 for AMOP and CMOP, respectively. The equilibrium adsorption data fitted into both the Langmuir and Freundlich isotherms. Gibbs free energy change (${\Delta}G^o$), enthalpy change (${\Delta}H^o$) and entropy change (${\Delta}S^o$) indicated that the adsorption of OFX was feasible, spontaneous, exothermic and occurred via the physisorption mode. Adsorption kinetics obeyed the Blanchard pseudo-second-order model. The results may find applications in the adsorptive removal of micro-contaminants of pharmaceutical origin from wastewater.

• Nuclear Engineering and Technology
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• 제54권6호
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• pp.1991-2003
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• 2022

The problem of water contamination by long-living cesium and strontium radionuclides is an urgent environmental issue. The development of facile and efficient technologies based on nanostructured adsorbents is a perspective for selective radionuclides removal. In this regard, current work aimed to obtain the nanostructured magnetic zeolite composites with high adsorption performance to cesium and strontium ions. The optimal conditions of hydrothermal synthesis were established based on XRD, SEM-EDX, N₂ adsorption-desorption, VSM, and batch adsorption experiment data. The role of chemical composition, textural characteristics, and surface morphology was demonstrated. The monolayer ionexchange mechanism was proposed based on adsorption isotherm modeling. The highest Langmuir adsorption capacity of 229.6 and 105.1 mg/g towards cesium and strontium ions was reached for composite obtained at 90 ℃ hydrothermal treatment. It was shown that magnetic characteristics of zeolite composites allowing to separate spent adsorbents by a magnet from aqueous solutions.

• Composites Research
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• 제35권6호
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• pp.402-411
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• 2022

In this study, the channels-contained hybrid membranes have been fabricated through the incorporation of glass fibers and GO sheets (GO/glass fibers, GG), or a mixture of chitosan/GO (CS/GO/glass fibers, CGG), as hybrid membranes using in organic dye removal. The material properties are well investigated the terms in the morphological, chemical, crystal, and thermal characterizations for verifying interactions in their formed structure. These hybrid membranes have been fitted well in pseudo-second order and Langmuir models that are associated with chemical adsorption and a monolayer approach, respectively. The highest adsorption ability of methylene blue and methyl orange reached 59.40 mg/g and 229.07 mg/g (GG); and 287.47 mg/g and 252.91 mg/g (CGG), which is more enhanced than that of previous GO-based other adsorbents. Moreover, the dye separation on these membranes could be favorable to superb sealing and trapping dye molecules from water instead of only the dye connection occurring on their surface, regarding the physically sieving effect. The membranes can also be reused within two and three adsorbing-desorbing cycles on the GG and CGG ones, respectively. These membranes can become future adsorbents to be applied for wastewater treatment due to their structural features.

• 공업화학
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• 제33권4호
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• pp.352-366
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• 2022

Nuclear power plant operations for electricity generation, rare-earth mining, nuclear medical research, and nuclear weapons reprocessing considerably increase radioactive waste, necessitating massive efforts to eradicate radioactive waste from aquatic environments. Cobalt (⁵⁸Co) and strontium (⁹⁰Sr) radioactive elements have been extensively employed in energy generation, nuclear weapon testing, and the manufacture of healthcare products. The erroneous discharge of these elements as pollutants into the aquatic system, radiation emissions, and long-term disposal is extremely detrimental to humans and aquatic biota. Numerous methods for treating radioactive waste-contaminated water have emerged, among which the adsorption process has been promoted for its efficacy in eliminating radioactive waste from aquatic habitats. The current review discusses the adsorptive removal of radioactive waste from aqueous solutions using low-cost adsorbents, such as graphene oxide, metal-organic frameworks, and inorganic metal oxides, as well as their composites. The chemical modification of adsorbents to increase their removal efficiency is also discussed. Finally, the current state of ⁵⁸Co and ⁹⁰Sr removal performances is summarized and the efficiencies of various adsorbents are compared.

• 공업화학
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• 제10권4호
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• pp.543-547
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• 1999

본 연구는 현재 폐기되고 있는 미연탄소분을 많이 함유한 비산회재를 이용하여 흡착제를 제조하고자 하였으며, 제조된 흡착제에 대한 중금속 제거 실험을 통하여 중금속을 함유한 폐수처리기의 적용가능성을 알아보았다. 비산회재에 장성탄의 혼합비율을 달리하여 세 종류의 펠릿을 제조하였으며, 장성탄의 혼합비율이 증가함에 따라 펠릿의 고정탄소함유량이 증가하였다. 이를 이용하여 탄화와 활성화를 거처 85~96%의 경도와 100~300 mg/g의 요오드 흡착량을 갖는 흡착제를 제조하였으며, 장성탄 혼합비율이 증가할수록 경도 및 요오드 흡착량이 증가함을 알 수 있었다. 중금속의 제거실험에서 제조된 흡착제에 대한 Pb와 Cr의 제거율이 90% 이상을 나타내었으며, 비산회재의 겨우 Pb 31.5%, Cr 5.6%의 낮은 제거율을 보였다. 이는 활성과정동안 비산회재에 함유된 미연탄소분과 $SiO_2$에 의하여 흡착성능이 증가되었기 때문이다.

• 청정기술
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• 제19권4호
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• pp.370-378
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• 2013

본 논고에서는 가스 흡착 분리 산업에서 광범위하게 적용되고 있는 압력순환흡착(pressure swing adsorption, PSA) 기술의 전형적인 흡착조건인 $15{\sim}40^{\circ}C$의 온도와 4~6 bar의 압력에서 금속-유기 골격체(metal-organic frameworks, MOF)와 제올라이트 이미다졸레이트 골격체(zeolite imidazolate frameworks, ZIF)의 $CO_2$ 흡착성능을 살펴보고 이들이 가지고 있는 장 단점을 분석해보고자 한다. $CO_2$는 $H_2$, CO, $N_2$ 및 $CH_4$와 같은 기체분자들에 비해 큰 분극률을 가지므로 동일한 세공크기라면 흡착제의 비표면적이 클수록 높은 흡착량을 보이며, $CO_2$의 분자크기($3.3{\AA}$)보다 큰 세공으로 이루어진 흡착제라면 상기 흡착조건에서의 $CO_2$ 흡착성능은 세공크기에 크게 영향을 받는다. MOF와 ZIF의 $CO_2$ 흡착성능은 이들의 골격을 이루는 금속과 유기 링커의 종류, 세공크기, 비표면적, 흡착조건(온도와 압력) 등에 따라 달라질 수 있지만, 특히 흡착압력의 영향이 절대적이다. 다시 말하면, $CO_2$의 흡착압력이 비슷할 경우 MOF와 ZIF의 $CO_2$ 흡착량에 미치는 상기 인자들의 영향은 비교적 작다. 15 bar 이상의 $CO_2$ 흡착압력에서 이 흡착제들이 수 십 mmol/g의 흡착성능을 나타낸다고 할지라도, 전형적인 PSA 공정조건에서 이들의 $CO_2$ 흡착성능은 제올라이트, 활성탄과 같은 벤치마크 흡착제들의 성능과 유사하거나 오히려 낮을 뿐만아니라, 이들의 가격은 벤치마크들에 비해 매우 높기 때문에 경제성 확보에 어려움이 있다.

• 한국전기화학회:학술대회논문집
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• 한국전기화학회 2005년도 수소연료전지공동심포지움 2005논문집
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• pp.159-162
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• 2005

• 한국세라믹학회지
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• 제53권4호
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• pp.429-434
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• 2016

Here, we introduce a means of utilizing waste oyster shells which were obtained from temporary storage near coastal workplaces as $CO_2$ adsorbents. The calcined CaO can be easily dissociated to $Ca^{2+}$ cation and $CO_3{^{2-}}$ anion by hydrolysis and gas-liquid carbonation reaction and converted to precipitated calcium carbonate (PCC) in algae-containing water. The calcium hydroxide and carbonation combination in algae-containing water significantly contributed to improving water quality which is very dependent on the addition amount of calcined powders.

• 약학회지
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• 제36권6호
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• pp.563-569
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• 1992

The sorption and desorption properties of four different solid adsorbents were evaluated for the trace enrichment of ibuprofen from biological samples. Chromosorb 107 gave the highest dynamic adsorption coefficient. Among the organic solvents examined, acetone gave the highest desorption coefficient. Using the Chromosorb 107 column, the optimum elution volume of the eluting solvent was evaluated from the breakthrough curve of ibuprofen. The usefulness of Chromosorb 107 as the solid adsorbent and acetone as the eluting solvent was examined for the solid-phase extraction of ibuprofen from serum in the concentration range of $20{\sim}40\;{\mu}g/ml$.