• Bulletin of the Korean Chemical Society
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• 제22권7호
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• pp.699-702
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• 2001

A series of cleft-type ionophores having two convergent hydroxamic acid functions are prepared and their selective ionophoric properties toward heavy metal and transition metal ions have been investigated. Hydroxamic acids 3 exhibited a prominent selectivity toward heavy metal ions of Hg2+ and Pb2+, and transition metal ions of Cu2+ over other transition metal and alkaline earth metal ions from slightly acidic source phase (pH 6) to an acidic receiving phase (pH 1). Selective ionophoric properties toward Pb2+ and Cu2+ ions over other surveyed metal ions are also confirmed by the FAB-MS measurements.

• Bulletin of the Korean Chemical Society
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• 제20권5호
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• pp.556-558
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• 1999

Lead-selective PVC membrane electrodes based on newly synthesized bis(crown ether)s containing 18-crown-6 moiety was prepared using standard PVC membrane composition. In order to monitor lead in environmental samples by lead sensor, especially good selectivity over alkali and alkaline earth metals has to be obtained. Thus, responses of the PVC membrane prepared with new bis(crown ether)s and Fluka ionophore V (crown ether) base to various cations include lead, alkali and alkaline earth metal ions were investigated for their use as a lead sensor. The polymeric liquid membrane based on trans-1 8-crown-6 ether exhibits the best overall potentiometric performances as a lead-selective electrode in terms of a wide linear dynamic range (between 10-6 and 10-2 M, Pb2+), excellent detection limit (less than 10-6 M) and good durability within limited error. The preferences of lead over other cations, such as Ag+, Hg2+, Na+, Ca2+ and even K+ in the aforementioned electrode are much better than the Fluka ionophore V system.

• 멤브레인
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• 제12권2호
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• pp.107-119
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• 2002

이번 연구에서 효율적인 기체분리를 위한 탄소-실리카($C-SiO_2$) 분리막이 방향족 이미드 블록과 실록산 블록으로 구성된 공중합체의 비활성분위기에서의 열분해를 통해 제조되었다. 이 탄소-실리카 기체분리막은 비교적 작은 크기의 기체분리, 즉 $He/N_2, O_2/N_2$ 그리고 $Co_2/N_2$의 분리에 있어 매우 뛰어난 기체선택도를 나타내었다. 두 상을 가진 공중합체의 열분해는 600도, 800도 그리고 1000도의 최종열분해온도로서 수행되었으며, 이러한 두 상으로 이루어진 전구체는 탄소막의 제조에 처음으로 보고되었다. 이러한 전구체는 두 상의 조성 및 같은 조성에서 중합방법의 차이에 의해 형성되는 모폴로지의 변화가 최종 탄소-실리카막의 기체분리특성에 미치는 영향을 살피기 위해 제조되었다. 이러한 탄소-실리카분리막은 $2.6-3.6{\AA}$의 동력학적 반경을 가진 작은 기체분자(헬륨, 산소, 질소, 이산화탄소)들을 사용한 기체투과실험에서, 탄소-실리카 분리막은 높은 투과도와 함께 뛰어난 분자체 효과를 보였다. 게다가 탄소-실리카분리막의 기체분리특성은 사용한 고분자 전구체의 기체분리특성과 매우 유사하며, 이것은 열적으로 안정한 두상의 사용으로 전구체의 초기 모폴로지가 열처리 후에도 상당히 유지되었기 때문이다. 현재의 연구는 탄소막 전구체의 초기의 모폴로지가 최종 탄소막의 분리특성 및 미세구조에 결정적인 영향을 미침을 암시한다.

• 멤브레인
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• 제28권6호
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• pp.424-431
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• 2018

Cobalt tetraphenylporphyrin-benzylimidazole (CoTpp-BIm)을 산소 운반체로 이용하여 polyethersulfone (PES)와의 혼합물을 기반으로 하는 혼합 구조의 평판형 분리막의 기체 분리 성능을 조사하였다. CoTpp-BIm이 혼합된 PES막은 손가락 구조와 스폰지형 구조가 혼합된 비대칭 구조를 가졌고, 상부표면은 치밀한 형태를 보였다. 기체분리 성능 실험은 94%의 $N_2$ 기체에 6%의 $O_2$가 혼합된 기체를 사용하여 평가하였다. 산소 및 질소 투과율은 ${\Delta}P$가 15~228 cmHg 범위에서 실험하였고, PES막의 투과면은 진공수준으로 유지되었다. CoTpp-BIm이 혼합된 PES막의 산소 투과율은 공급 압력이 감소함에 따라 증가하였다. 공급 압력이 15 cmHg일 때 산소 투과율($P_{O_2}$)는 6676 Barrer이었고, $O_2/N_2$ 선택도(${\alpha}$)는 6.1, 촉진인자(F)는 2.39까지 증가하였다. 이를 바탕으로 PES막에 CoTpp-BIm을 첨가하면 산소분리 특성이 향상되는 것을 확인하였다.

• Bulletin of the Korean Chemical Society
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• 제32권3호
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• pp.800-804
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• 2011

A potentiometric sensor based on the Schiff base $(N^2E,N^{2'}E)-N^2,N^{2'}$-bis(thiophen-2-ylmethylene)-1,1'-binaphthl-2,2'-diamine has been synthesized and explored as an ionophore PVC-based membrane sensor selective for the silver ($Ag^+$) ion. Potentiometric investigations indicate a high affinity of this receptor for the silver ion. Seven membranes have been fabricated with different compositions, with the best performance shown by the membrane with an ionophore composition (w/w) of: 1.0 mg, PVC: 33.0 mg, DOA: 66.0 mg in 1.0 mL THF. The sensor worked well within a wide concentration range of $1.0{\times}10^{-2}$ to $1.0{\times}10^{-7}$ M, at pH 5, at room temperature (slope 57.4 mV/dec.), and with a rapid response time of 9 s; the sensor also showed good selectivity towards the silver ion over a huge number of interfering cations, with the highest selectivity coefficient for $Hg^{2+}$ at -3.7. Thus far, the best lower detection limit was $4.0{\times}10^{-8}$ M.

• Bulletin of the Korean Chemical Society
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• 제25권9호
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• pp.1371-1378
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• 2004

A porous stainless steel (SUS) as a substrate of silica composite membranes for hydrogen purification was used to improve mechanical strength of the membranes for industrial application. The SUS support was successfully modified by using submicron Ni powder, $SiO_2$ sols with particle size of 500 nm and 150 nm in turns. Silica top layer was coated on the modified supports under various preparation conditions such as calcination temperature, dipping time and repeating number of dipping-drying process. The calcination temperature for proper sintering was between H ttig temperature and Tamman temperature of the coating materials. Maximum hydrogen selectivity was investigated by changing dipping time. As repeating number of dipping-drying process increased, permeances of nitrogen and hydrogen were decreased and $H_2/N_2$ selectivity was increased due to the reduction of non-selective pinholes and mesopores. For the silica membrane prepared under optimized conditions, permeance of hydrogen was about $3\;{\times}\;10^{-5}\;cm^3{\cdot}cm^{-2}{\cdot}s^{-1}{\cdot}cmHg^{-1}$ combined with $H_2/N_2$ seletivity of about 20.

• KSBB Journal
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• 제13권1호
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• pp.38-43
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• 1998

Application of pervaporative extraction of ethanol to simultaneous saccharification and fermentation(SSF) of cellulose was investigated. From batch experiments, optimum cellulose substrate and enzyme loadings were found to be 10% and 15 IFPU/g cellulose, respectively. The cellulose conversion was lowered in fed-batch system due to the ethanol accumulation. The activity of the yeast Saccharomyces uvarum used in this study was significantly reduced at ethanol concentrations above around 40 g/L. From pervaporation experiments using PDMS membrane, ethanol was efficiently separated at 38$^\circ C$ and 10 mmHg of a down stream pressure. The pervaporation unit with 240 cm$^2$ of surface area was combined into the SSF reactor. The continuous removal of ethanol by pervaporation during SSF resulted in an improved cellulose conversion. Within the scope of this experiment, ethanol yields in the pervaporative SSF and simple SSF were 68.3% and 56.6%, respectively. The permeate flux for SSF broth pervaporation was about one-half that for the pervaporation of aqueous ethanol solution. Accordingly, the development of a membrane with higher ethanol selectivity and flux will increase the feasibility of this technology.

• Bulletin of the Korean Chemical Society
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• 제31권11호
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• pp.3212-3216
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• 2010

A new rhodamine-based sensor 1 was designed and synthesized by incorporating rhodamine B and benzimidazole moieties. Sensor 1 exhibits high selectivity and sensitivity to $Cu^{2+}$ in $CH_3CN$-water solution (HEPES buffer, pH = 7.0) with an obvious color change from colorless to pink. Other metal ions such as $Hg^{2+}$, $Ag^+$, $Pb^{2+}$, $Sr^{2+}$, $Ba^{2+}$, $Cd^{2+}$, $Ni^{2+}$, $Co^{2+}$, $Fe^{2+}$, $Mn^{2+}$, $Cu^{2+}$, $Zn^{2+}$, $Ce^{3+}$, $Mg^{2+}$, $K^+$ and $Na^+$ had no such color change and have no significant influence on $Cu^{2+}$ recognition process. The interaction of $Cu^{2+}$ and sensor 1 was proven to adopt a 1:1 binding stoichiometry and the recognition process is reversible.

• 멤브레인
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• 제25권5호
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• pp.398-405
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• 2015

용액-확산 메커니즘에 의해 결정되는 기존의 고분자에서와는 달리, 촉진수송은 투과도와 선택도를 동시에 향상시킬 수 있는 기술이다. 본 연구에서는 은 나노입자, 폴리비닐피롤리돈, 7,7,8,8-테트라시야노퀴노디메탄으로 구성된 촉진수송 올레핀 분리막에 있어서, 메조기공 티타늄산화물($m-TiO_2$)에 대한 영향을 연구하였다. 특히 메조기공 티타늄산화물은 폴리비닐클로라이드-g-폴리옥시에틸렌 메타크릴레이트 가지형 공중합체를 템플레이트로 하여 쉽고 대량 생산이 가능한 방법으로 제조하였다. 엑스레이 회절분석에 따르면, 제조된 메조기공 티타늄산화물은 아나타제와 루타일 상의 혼합으로 구성되어 있으며, 결정의 크기가 약 16 nm 정도 되었다. 메조기공 티타늄산화물을 첨가하였을 때, 분리막의 확산도가 증가하여 혼합기체 투과도가 1.6에서 16 GPU로 증가하였고 선택도는 45에서 37로 약간 감소하였다. 메조기공 티타늄산화물이 첨가되지 않은 분리막은 장시간 성능이 유지되었으나, 메조기공 티타늄산화물이 첨가된 분리막의 경우 시간이 지남에 따라 투과도와 선택도가 감소하였다. 이는 티타늄산화물과 은 사이의 화학적 상호작용으로 은 나노입자의 올레핀 운반체로써의 활성을 감소시키기 때문으로 사료된다.

• Elastomers and Composites
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• 제33권1호
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• pp.37-43
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• 1998

The permeation of gas through polymer membrane at temperatures above its glass transition, generally occurs by a solution-diffusion mechanism. This mechanism is performed by the affinity difference between polymeric materials and gas molecules, and various technologies, such as copolymerization, impregnation and so on, have been researched to improve the affinity of polymeric material for the gases. In this study, permeability and selectivity for some gases were obtained from steady-state rates of gas permeation through silicone rubber membrane which is prepared by supercritical fluid extraction method. The permeability was measured by the volumetric method proposed by Barrer. Permeability was increased generally with temperature and permeation pressure. Silicone rubber membrane shows a higher permeability to $CO_2$ than to $O_2$, $N_2$. This results probably reflect the relatively high solubility of CO_2 in silicone rubber membrane, which is due to the affinity of $CO_2$ molecules. Since separation powers of $CO_2/N_2$, $CO_2/O_2$ were more than 200, and 100, respectively, it is able to separate $CO_2$ from the air, and the optimum temperature and pres-sure was 328.15 K, 60 cmHg respectively. In future, it is possible that the silicone rubber membrane can be used for separation or concentration of $CO_2$ through experiment for mixed gas separation.