The CO2 separation membranes based on a graft copolymer consisting of hydrophobic poly(ethylene-alt-maleic anhydride) (PEMA) backbone and hydrophilic poly(propylene glycol) PPG side chains were fabricated by a facile one-pot process. The reaction between O-(2-aminopropyl)-O’-(2-methoxyethyl) polypropylene glycol (AMPPG) and PEMA was conducted in butanol at room-temperature. Without any post-treatment, the as-synthesized PEMA-g-PPG solution could be directly coated onto a microporous polysulfone support to fabricate thin-film composite membranes. The PEMA-g-PPG membrane exhibited high selectivity (82.6 for CO2/N2 and 26.8 for CO2/CH4) and good CO2 permeability (99.1 Barrer), which is a close value to the upper boundary limit (2008). The PEMA-g-PPG membrane could be commercially feasible owing to simple, inexpensive and scalable process.

Piezodialysis involves the preferential permeation of ions over water molecules through charge mosaic membranes (CMM). This energy-efficient process incites interest as an alternative route to water desalination. But the development of effective CMMs remains a challenge due to their difficult fabrication. Herein, preparation of the positive and negative domains of a CMM were optimized. Negative poly(sodium styrene sulfonate) was blended in poly(vinyl alcohol) matrix, same as that of the positive poly(diallyldimethyl ammonium chloride). Results reveal that a balance between the two domains is critical for the CMM to achieve high salt enrichment and mechanical stability. This work was supported by NRF funded by the Korea government (MSIP) (No. 2017R1A2B2002109) and Basic Science Research Program of Ministry of Education (2009-0093816).

역삼투 공정은 현재 해수담수화 공정으로 가장 많이 사용되는 공정으로 향후 지속적으로 사용량이 증가될것으로 보인다. 보론은 인체와 동물, 식물에게 필수적인 영양소이지만, 과잉 공급된 보론은 인체 및 식물의 신경계 장애 및 생식능력 저하를 초래하고, 식물성장 및 과실의 성장을 방해하는 독성물질로 의심받고 있다. 보론은 흔히 쓰이는 하수처리 및 폐수처리 공정에서 제거되지 않으며, 역삼투 공정에서도 중성인 B(OH)3로 남아 있어 역삼투 후에 보론 한계기준보다 훨씬 높은 농도가 생산수에 존재하는 경우가 종종 있다. 그래서 물에서 보론이 제거되는 공정이 절실한 상황이다. 본 연구에서는 보론 제거율 향상을 위해 첨가제를 활용한 polyamide를 계면중합을 통해 합성하여 역삼투막을 제조하였으며, 제조된 역삼투막의 성능평가를 수행, 비교하였다.

제련 과정 중 발생하는 폐황산에는 다양한 희소금속들이 포함되어 있으나, 공정수에서 희소금속 회수가 처리기술 부족으로 중화되어 폐기되고 있는 실정이다. 일반적으로 습식제련공정에서의 모액(침출액)은 황산(10~15%) 용액 상태이며, 모액중의 유가금속 (Cu, Zn 등) 및 희소금속(In, Se, Re 등)은 보통 수 ppm에서 수 % 단위로 용해되어 있다. 희소금속은 첨단소재로서의 가치가 높고 수요가 급증하고 있으나 공정수에서 희소금속 처리 기술 부족으로 폐 황산 속 희소금속은 중화되어 폐기되고 있다. 희소금속 처리기술로서 분리막 공정을 희소금속 회수에 적용하면 효율적인 분리/농축을 가능하게 하여 경제적인 이점이 있다. 본 연구에서는 내산성이 뛰어난 방향족 모노머인 메타페닐렌디아민과 파라페닐렌디아민, 지방족 아민모노머인 피페라진와 블렌딩하여 계면중합을 실시하고 물성을 평가한다. 그리고 제조된 분리막의 내산성을 평가하기 위하여 15 wt% 황산용액에 침지한 후 투과성능을 측정하였다.

이온교환막은 양이온 및 음이온을 선택적으로 분리할 수 있는 이온선택성을 지닌 막으로, 연료전지, 레독스전지, 전기투석, 역전기투석 등 다양한 분야에 응용되고 있다. 본 연구에서는 암모늄 및 비닐 그룹이 수식된 실란들과 솔-젤 법을 이용해 암모늄 그룹과 비닐 그룹을 동시에 지니는 올리고실록산 수지를 합성했고, 본 수지와 비닐 및 아크릴아마이드계 모노머 solution의 광라디칼 중합반응과 PE계 다공성 지지체를 활용해 실리콘-비닐 하이브리드 음이온교환막을 제조했다. 합성된 올리고실록산 수지는 FT-IR 및 29 Si NMR에 의해 분석되었고, 수지 내 실록산 결합이 성공적으로 형성되었음을 확인했다. 또한, 제조된 실리콘-비닐 하이브리드 음이온교환막은 swelling 후 약 20um 두께를 지니고 있었고, 0.6 Ω·cm² 이하의 저항, 85%의 permselectivity, 1.5 meq g-1 정도의 ion exchange capacity (IEC)를 지니고 있었다.

본 연구에서는 다공성 PAN(Polyacrylonitrile) 중공사 분리막을 지지체로 이용하여 계면중합반응을 통해 나노여과막을 제조하였다. 지지체로는 PAN을 사용하였으며 수용상으로는 피페라진으로 중공사 분리막 내부에 코팅한 후 유기상인 TMC와 반응하여 계면중합이 일어나도록 진행하였다. 지지체로 사용된 UF 중공사 분리막은 분획분자량 10,000, 30,000, 100,000Da를 각각 사용하였으며 피페라진(Piperazine) 농도를 0.1%, 02%, 0.3%, TMC(Trimesoyl Chloride)의 농도를 0.05%, 0.1%, 0.2%로 변화시켜 제조 하여 5bar에서의 수투과도(LMH)와 MgSO4 2000ppm, Na2SO4 2000ppm, NaCl 500ppm 수용액으로부터 염배제율(Rejection, %)을 확인하였다.

We report on a unique fabrication technique, DSC for high performance PA TFC RO membranes. DSC allows the simultaneous and continuous spreading of two reactive monomer solutions to create an unsupported PA layer, which is then adhered onto a porous support to form a membrane. DSC facilitates the characterization of the PA layer structure by easily isolating it. The DSC-PA layer exhibits a thinner and smoother structure with a more wettable and less negatively charged surface than one prepared via conventional interfacial polymerization (IP). DSC enables the formation of an extremely thin (~9 nm) and dense PA layer using a very low MPD concentration, which is not feasible by conventional IP. Importantly, the DSC-assembled membrane shows the excellent water flux and NaCl rejection, exceeding both the IP control and commercial RO membranes.

Amylose is carbohydrate polymer defined as a linear natural polysaccharide composed of α(1→4) bound glucose units. Due to its abundance, renewable nature, low cost, and biodegradability, this polymer is regarded as a promising green material for producing crystals and particles of different sizes ranging from the nanometer scale to the micrometer scale. Herein, short amylose chains and dextran-coated iron oxide magnetic nanoparticles (Dex@MNPs) were introduced to fabricate individual superparamagnetic amylose microparticles (SAMPs), which have a well-defined spherical shape and a uniform size of about 1 μm. We found that the aggregation of SAMPs can be mediated by the introduced Dex@MNPs in a concentration-dependent manner, indicating that Dex@MNPs, as the seed crystals, play an important role in self-assembly of SAMPs. By using streptococcal protein G tagged with maltose binding protein (MBP-SPG), specific antibody against Escherichia coli O157:H7 was successfully immobilized on the surface of SAMPs. The Ab-functionalized SAMPs showed a high capture efficiency (>90%) comparable to the commercial immunomagnetic microparticles regardless of suspending agents (1X PBS and milk). Moreover, SAMPs exhibited excellent recyclability, in which the Ab immobilized on the surface of SAMPs can be refreshed by using the maltose elution buffer along with the unchanged capture efficiency. In addition, SAMPs were assembled into the linear rod-shape microstructure by the introduced magnetic field during the amylose-mediated precipitation process. The convenient self-assembly of SAMPs with the well-defined size and shape, biocompatibility, tolerance to environmental variances, high magnetic response behavior, and excellent recyclability in the functionalization make these magnetic microparticles promising for many potential applications such as bio-sensing, labeling, and smart delivery of active compounds.

Titanium carbide (TiC) powders are successfully synthesized by carburization of titanium hydride (TiH2) powders. The TiH2 powders with size lower than 45 μm (-325 Mesh) are optimally produced by the hydrogenation process, and are mixed with graphite powder by ball milling. The mixtures are then heat-treated in an Ar atmosphere at 800-1200oC for carburization to occur. It has been experimentally and thermodynamically determined that the dehydrogenation, “TiH2 = Ti + H2”, and carburization, “Ti + C = TiC”, occur simultaneously over the reaction temperature range. The unreacted graphite content (free carbon) in each product is precisely measured by acid dissolution and by the filtering method, and it is possible to conclude that the maximal carbon stoichiometry of TiC0.94 is accomplished at 1200oC.

Electrical wire explosion in liquid media is a promising method for producing metallic nanopowders. It is possible to obtain high-purity metallic nanoparticles and uniform-sized nanopowder with excellent dispersion stability using this electrical wire explosion method. In this study, Ni-Fe alloy nanopowders with core-shell structures are fabricated via the electrical explosion of Ni-Fe alloy wires 0.1 mm in diameter and 20 mm in length in de-ionized water. The size and shape of the powders are investigated by field-emission scanning electron microscopy, transmission electron microscopy, and laser particle size analysis. Phase analysis and grain size determination are conducted by X-ray diffraction. The result indicate that a core-shell structured Ni-Fe nanopowder is synthesized with an average particle size of approximately 28 nm, and nanosized Ni core particles are encapsulated by an Fe nanolayer.

This study was carried out to investigate the characterization of iron oxide nanotubes (INTs) by anodization method and applied adsorption isotherms and kinetic models for phosphate adsorption. SEM analysis was conducted to examine the INTs surface formation. Further XRD and XPS analysis were performed to observe the crystal structure of INTs before and after phosphate adsorption. AFM analysis was conducted to determine of Fe foil surface before and after anodization. Phosphate stock solution for adsorption experiment was prepared by KH2PO4. The batch experiment was conducted using 20 ml phosphate stock solution and 40 cm3 of INTs in 50 ml conical tube. Adsorption isotherms were applied Langmuir and Freundlich models for adsorption equilibrium test of INTs. Pseudo first order and pseudo second order models were applied for interpretation of adsorption rate by reaction time. The determination coefficient (R2) values of Langmuir and Freundlich models were 0.9157 and 0.8876 respectively.

In order to identify changes in the nature of the particles due to changes in the inflow rate of the raw material solution, the present study was intended to prepare nano-sized cobalt oxide (Co3O4) powder with an average particle size of 50 nm or less by spray pyrolysis reaction using raw cobalt chloride solution. As the inflow rate of the raw material solution increased, droplets formed by the pyrolysis reaction showed more divided form and the particle size distribution was more uneven. As the inflow rate of the solution increased from 2 to 10 ml/min, the average particle size of the formed particles increased from about 25 nm to 40 nm, while the average particle size did not show significant changes when the inflow rate increased from 10 to 50 ml/min. XRD analysis showed that the intensity of the XRD peaks increased remarkably when the inflow rate of the solution increased from 2 to 10 ml/min. On the other hand, the peak intensity stayed almost constant when the inflow rate increased from 10 to 50 ml/min. With the increase in the inflow rate from 2 to 10 ml/min, the specific surface area of the particles decreased by approximately 20 %. On the contrary, the specific surface area stayed constant when the inflow rate increased from 10 to 50 ml/min.

Graphene has shown exceptional properties for high performance devices due to its high carrier mobility. Of particular interest is the potential use of graphene nanoribbons as field-effect transistors. Herein, we introduce a facile approach to the fabrication of graphene nanoribbon (GNR) arrays with ~200 nm width using nanoimprint lithography (NIL), which is a simple and robust method for patterning with high fidelity over a large area. To realize a 2D material-based device, we integrated the graphene nanoribbon arrays in field effect transistors (GNR-FETs) using conventional lithography and metallization on highly-doped Si/SiO2 substrate. Consequently, we observed an enhancement of the performance of the GNRtransistors compared to that of the micro-ribbon graphene transistors. Besides this, using a transfer printing process on a flexible polymeric substrate, we demonstrated graphene-silicon junction structures that use CVD grown graphene as flexible electrodes for Si based transistors.

Particle morphology change and different experimental condition analysis during composite fabrication process by traditional ball milling with discrete element method (DEM) simulation were investigated. A simulation of the three dimensional motion of balls in a traditional ball mill for research on the grinding mechanism was carried out by DEM simulation. We studied the motion of the balls, the ball behavior energy and velocity; the forces acting on the balls were calculated using traditional ball milling as simulated by DEM. The effect of the operational variables such as the rotational speed, ball material and size on the flow velocity, collision force and total impact energy were analyzed. The results showed that increased rotation speed with interaction impact energy between balls and balls, balls and pots and walls and balls. The rotation speed increases with an increase of the impact energy. Experiments were conducted to quantify the grinding performance under the same conditions. Furthermore, the results showed that ball motion affects the particle morphology, which changed from irregular type to plate type with increasing rotation speed. The evolution was also found to depend on the impact energy increase of the grinding media. These findings are useful to understand and optimize the particle motion and grinding behavior of traditional ball mills.

We report on the fabrication and characterization of a novel Cu2O/CuO heterojunction structure with CuO nanorods embedded in Cu2O thin film as an efficient photocathode for photoelectrochemical (PEC) solar water splitting. A CuO nanorod array was first prepared on an indium-tin-oxide-coated glass substrate via a seed-mediated hydrothermal synthesis method; then, a Cu2O thin film was electrodeposited onto the CuO nanorod array to form an oxide semiconductor heterostructure. The crystalline phases and morphologies of the heterojunction materials were examined using X-ray diffraction and scanning electron microscopy, as well as Raman scattering. The PEC properties of the fabricated Cu2O/CuO heterojunction photocathode were evaluated by photocurrent conversion efficiency measurements under white light illumination. From the observed PEC current density versus voltage (J-V) behavior, the Cu2O/CuO photocathode was found to exhibit negligible dark current and high photocurrent density, e.g. −1.05 mA/cm2 at −0.6 V vs. Hg/HgCl2 in 1 mM Na2SO4 electrolyte, revealing the effective operation of the oxide heterostructure. The photocurrent conversion efficiency of the Cu2O/CuO photocathode was estimated to be 1.27% at −0.6 V vs. Hg/HgCl2. Moreover, the PEC current density versus time (J-T) profile measured at −0.5 V vs. Hg/HgCl2 on the Cu2O/CuO photocathode indicated a 3-fold increase in the photocurrent density compared to that of a simple Cu2O thin film photocathode. The improved PEC performance was attributed to a certain synergistic effect of the bilayer heterostructure on the light absorption and electron-hole recombination processes.

Thermally rearranged polybenzoxazole (TR-PBO) membranes has a excellent gas separation properties due to its high fractional free volume and suitable cavity size.1) Furthermore, thermally rearranged poly(benzoxazole-co-imide) (TR-PBOI) materials show the improved mechanical strength and gas separation properties.2) In this study, TR-PBOI asymmetric hollow fiber membranes was fabricated via NIPS method. In detail, the influence of co-solvent system and polymeric additives with various molecular weight on gas separation performance was observed. For further performance optimization, dope & bore flow rate and coagulation temperature were controlled.3) The characterization on membranes was conducted by FE-SEM, pure and mixed gas permeation test with micro-GC system.

이산화탄소를 분리하기 위한 한 방법으로 고분자 기체 분리막을 이용한 기술이 발전하고 있다. 다양한 폴리머 멤브레인 재료 중에서도 폴리이미드(PI) 는 우 수한 열 및 기계적 특성, 좋은 화학적 안정성과 높은 가스 수송 특성을 가지고 있다. 하지만 고분자 분리막은 아직 낮은 투과, 선택성을 가지고 있기 때문에 이를 높이기 위해 많은 연구가 이루어지고 있다. 한편 고무상 고분자인 폴리에 틸렌글리콜 (PEG)은 이산화탄소에 대한 높은 친화성으로 우수한 이산화탄소 분리성능을 가지고 있다. 이에 본 연구에서는 높은 자유 체적을 가지는 durene group을 포함한 PI와 PEG를 공중합 시켜 높은 소재의 기체 투과성능을 확인하고 이 소재를 이용하여 중공사 제조 변수를 조절에 따른 기체 투과도를 확인 하였다.