• Membrane and Water Treatment
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• 제13권6호
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• pp.259-290
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• 2022

Carbon nanotubes (CNTs), due to their excellent physical, chemical and mechanical properties and their ability to prepare new membranes with attractive properties, have found applications in water and wastewater technology. CNT functionalization, which involves the introduction of different types of functional groups into pure CNTs, improves the capabilities of CNT membranes for water and wastewater treatment. It turns out that CNT-based membranes have many advantages, including enhanced water permeability, high selectivity and anti-fouling properties. However, their full-scale application is still limited by their high cost. With their tremendous separation efficiency, low biofouling potential and ultra-high water flux, CNT membranes have the potential to be a leading technology in water treatment in the future, especially in desalination.

• Membrane and Water Treatment
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• 제6권1호
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• pp.1-13
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• 2015

The modification of ultrafiltration membranes with carbon nanotube (CNT) buckypaper on fouling control was investigated. Two types of commercially available flat-sheet membranes were used: PS35 and PES900C/D (PES) (the PS35 membranes were hydrophilic with a molecular weight cutoff of 20 kDa, and the PES membranes were hydrophobic with a molecular weight cutoff of 20 kDa). The CNT buckypaper modified ultrafiltration membranes were prepared by filtering a CNT suspension through the flat-sheet membrane in a dead-end ultrafiltration unit. After modification, the pure water flux of PES was significantly increased, while the pure water flux of PS35 was decreased. The properties of the CNT modified membranes were also investigated. Considering the antifouling properties, pure water flux of the modified membrane, and the stability of CNT buckypaper layer on the membrane surface, ethanol solution with a concentration of 50 wt.%, multi-walled carbon nanotubes (MWCNTs) with a larger diameter (30-50 nm), and the CNT loading with $7.5g/m^2$ was selected. The CNT buckypaper on the surface of ultrafiltration membranes can trap the pollutants in sewage effluent and prevent them reaching the surface of virgin membranes. Water quality analysis showed that the effluent quality of the modified membrane was obviously improved. The removal efficiency of humic acid and protein-like matters by the modified membrane was significant. These results indicate the potential application of the CNT buckypaper layer modified membranes in the field of wastewater reclaim.

• 멤브레인
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• 제28권6호
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• pp.388-394
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• 2018

탄소나노튜브(CNT) 기반의 멤브레인은 높은 물 전달률과 직경에 따른 이온 배제율로 해수담수, 물질 정화 등을 위한 분리막으로써의 가능성을 보여 주었다. 이온 선택성은 CNT 기반 멤브레인의 응용 분야를 확대하기 위한 중요한 요소이며, 기능기를 이용하여 이온 선택성의 조절이 가능함이 보고되었다. 다양한 원자가/크기의 이온이 혼합될 경우, 이온-기능기간 작용력 뿐만 아니라 이온-이온간의 작용력, 이온의 크기에 의한 반발력 등이 복합적으로 작용한다. 이에 본 연구에서는 분자동역학 전산모사를 통하여, 상이한 원자가/크기를 가진 이온의 혼합이 기능화된 CNT의 이온 선택성에 미치는 영향을 연구하였다. Potential of Mean Force 계산을 통하여 이온 투과에 대한 자유 에너지 장벽을 계산하였으며, CNT 크기 변화, 전하량 변화를 통하여 이온 선택성과 배제에 영향을 미치는 요소를 분석하였다. 본 연구는 CNT 멤브레인을 이용한 분리막 설계, 생체 이온 전달 채널 모사 등에 유용할 것으로 기대한다.

• Advances in nano research
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• 제12권3호
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• pp.253-261
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• 2022

Numerical modelling of an integrated Carbon NanoTube (CNT) membrane is only achievable if probable deformations and realistic alterations from a perfect CNT membrane are taken into account. Considering the possible forms of CNTs, bending is one of the most probable deformations in these high aspect ratio nanostructures. Hence, investigation of effect associated with bent CNTs are of great interest. In the present study, molecular dynamics simulation is utilized to investigate fluid flow dynamics in deformed CNT membranes, specifically when the tube cross section is not affected. Bending in armchair (5,5) CNT was simulated using Tersoff potential, prior to flow rate investigation. Also, to study effect of inclined entry of the CNT to the membrane wall, argon flow through generated inclined CNT membranes is examined. The results show significant variation in both cases, which can be interpreted as counter-intuitive, since the cross section of the CNT was not deformed in either case. The distribution of fluid-fluid and fluid-wall interaction potential is investigated to explain the anomalous behavior of the flow rate versus bending angle.

• 한국물환경학회지
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• 제28권1호
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• pp.148-156
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• 2012

In this research, the application of carbon nanotubes (CNTs) modified PVDF (polyvinylidene fluoride) membrane was tested as a simply and beginning attempt to overcome membrane fouling because CNTs importantly affect the transport of natural organic matter (NOM). Suwannee River fulvic acid (SRFA) as the representative of NOM was selected and its sorption results with single-walled CNT (SWCNT), multi-walled CNT (MWCNT), and oxidized MWCNT (O-MWCNT) were obtained through the batch experiment. SRFA sorption isotherms had a strong nonlinearity and its sorption capacity followed the order O-MWCNT < MWCNT < SWCNT. The adsorbed mass of SRFA on each CNT decreased as a function of pH due to their charge repulsion. For the CNT-PVDF membrane filtration experiments, the suspended CNT solution (10 mg/40 mL) was incorporated into $0.45{\mu}m$-PVDF membrane and 5 mg/L of SRFA solution was monitored using UV detector connected with high pressure pump after passing through CNT-PVDF membrane. The SRFA removal efficiency by MWCNT-PVDF membrane was the strongest among other modified membranes. This suggests that the CNT modified microfiltration (MF) membrane might effectively and selectively apply to treat the contaminated water including organic compounds in the presence of NOM.

• Korean Chemical Engineering Research
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• 제56권1호
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• pp.56-60
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• 2018

미세입자가 미치는 부정적인 영향으로 인해 관심이 증가하여 공기 중 미세입자를 제거할 수 있는 멤브레인 필터의 성능향상을 위해 다양한 방법을 도입하여 왔다. 필터 섬유 제조 기술 중 전기 방사 기술이 최근에 가장 주목을 받고 있으며, 수 백 nm에서 수 십 ${\mu}m$ 까지의 균일한 직경의 섬유를 제조 할 수 있는 장점을 가진다. 전기 방사 기술로 생성한 섬유는 초극세 섬유로서 섬유의 생성과 동시에 3차원의 네트워크로 적층된 형태의 다공성 웹은 초박막, 초경량이며 기존 섬유에 비해 부피 대비 표면적비가 높고, 높은 기공도를 가지는 멤브레인을 제조 할 수 있으므로, 전기 방사 멤브레인의 여과 필터 성능이 크게 향상 될 것으로 예상이 된다. 본 연구에서는 polystyrene, cellulose acetate 멤브레인 필터를 이용하여 섬유 두께, 탄소나노튜브의 조성비에 따른 필터로서의 여과성능을 살펴보았으며, 필터소재의 성능 비교실험 결과 적정량의 CNT 소재의 첨가로 인해 필터의 여과 성능이 향상되는 것을 알 수 있다.

• 멤브레인
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• 제26권5호
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• pp.351-364
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• 2016

최근 폴리아마이드 선택층에 나노물질을 혼합하여 해수담수화 성능을 높이고자 하는 연구가 활발히 이루어지고 있다. 본 총설은 역삼투 분리막 해수담수화 공정에서의 에너지 효율 향상을 위한 우수한 성능을 가진 폴리아마이드 기반 나노복합막을 소개하고자 한다. 그래핀 옥사이드 및 탄소나노튜브와 같은 탄소나노물질 및 제올라이트, 실리카 나노입자 등의 다양한 나노물질들이 기존 폴리아마이드의 투과분리성능을 높이기 위해 적용되고 있다. 본 총설에서는 최근 연구 중인 각 나노소재별 성능향상 특장점을 소개하고, 더 높은 성능을 갖는 나노복합막 제조를 위한 연구방향을 제시하고자 한다.

• 센서학회지
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• 제32권3호
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• pp.194-198
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• 2023

With the recent development of industrial technology, the problem of odor due to leakage of toxic gas discharged from industrial complexes is gradually increasing. Among them, hydrogen sulfide is a colorless representative odorous substance that can cause pain through irritation of the mucous membranes of the eyes and respiratory tract, and is a gas that can cause central nervous system paralysis and suffocation when exposed to high concentrations. Therefore, in order to improve the odor problem, research on a gas sensor capable of quickly and reliably detecting a leak of hydrogen sulfide is being actively conducted. A lot of research has been done on the existing metal oxide-based hydrogen sulfide gas sensor, but it has the disadvantage of requiring low selectivity and high temperature operating conditions. Therefore, in this study, a Pt/CNT-based electrochemical hydrogen sulfide gas sensor capable of detecting at low temperatures with high selectivity for hydrogen sulfide was developed. A working electrode capable of selectively detecting only hydrogen sulfide was fabricated by synthesizing Pt nanoparticles as a catalyst on functionalized CNT and applied to an electrochemical hydrogen sulfide gas sensor. It was confirmed that the manufactured Pt/CNT-based electrochemical hydrogen sulfide gas sensor has a current change of up to 100uA for hydrogen sulfide, and the both response time and recovery time were within 15 seconds.

• 한국광학회지
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• 제21권1호
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• pp.33-37
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• 2010

본 연구에서는 전도성이 매우 높은 탄소나노튜브 박막을 제작하고 테라파 영역에서의 광학상수를 측정하였다. 탄소나노튜브박막은 스핀코팅법 또는 진공여과법을 이용하여 연성플라스틱 기판 위에 증착되었다. 테라파 영역의 전자파 투과율은 박막의 두께조절을 통해 가능하며, 산처리 등의 후속공정을 통해서도 조절이 가능하다. 시분해 테라파 투과파의 진폭과 위상 측정을 통해유전상수를 포함한 광학상수의 스펙트럼을 측정하였다. 이를 통해 탄소나노튜브 박막이 Drude 자유전자 모델에 잘 부합하며, 높은 플라즈마 진동수를 가지는 등, 우수한 금속의 특성을 가지고 있음이 밝혀졌다. 또한 산처리 전후 유전상수가 변화하는 것을 직접확인할 수 있었다. 마지막으로 셀룰로즈 멤브레인에 증착된 CNT 필름의 경우엔 기판의 효과가 제거된 광학계수 측정이 가능함을 보여준다.

• Carbon letters
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• 제14권3호
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• pp.131-144
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• 2013

The carbon nanotube (CNT) represents one of the most unique inventions in the field of nanotechnology. CNTs have been studied closely over the last two decades by many researchers around the world due to their great potential in different fields. CNTs are rolled graphene with $SP^2$ hybridization. The important aspects of CNTs are their light weight, small size with a high aspect ratio, good tensile strength, and good conducting characteristics, which make them useful as fillers in different materials such as polymers, metallic surfaces and ceramics. CNTs also have potential applications in the field of nanotechnology, nanomedicine, transistors, actuators, sensors, membranes, and capacitors. There are various techniques which can be used for the synthesis of CNTs. These include the arc-discharge method, chemical vaporize deposition (CVD), the laser ablation method, and the sol gel method. CNTs can be single-walled, double-walled and multi-walled. CNTs have unique mechanical, electrical and optical properties, all of which have been extensively studied. The present review is focused on the synthesis, functionalization, properties and applications of CNTs. The toxic effect of CNTs is also presented in a summarized form.