• Elastomers and Composites
• /
• 제52권4호
• /
• pp.257-265
• /
• 2017

In this work, CR (Chloroprene Rubber) was emulsified by phase-inversion emulsification with nonionic surfactants (NP-1025, LE-1017, and OP-1019) and an anionic surfactant (SDBS; sodium dodecylbenzenesulfonate), and its stabilization was investigated through a study of its adsorption characteristics, zeta potential, and flow behavior. As the amount of the mixed surfactant increased, the droplet size decreased, resulting in the increase of viscosity. In particular, a CR emulsion with a lower absorbance in the UV spectrum exhibited the highest zeta potential. The results of this experiment showed that the CR emulsion prepared using (LE-1017) and SDBS was the most stable. In this study, calcium hydroxide and aluminum hydroxide were added to enhance the mechanical properties of the CR emulsion, and the relationship between tensile strength, tear strength and surface free energy were investigated. The tensile and tear strengths of the CR emulsion incresed as the amount of calcium hydroxide and aluminum hydroxide increased. The highest tensile and tear strengths and surface free energy were observed for additions of 1.0% calcium hydroxide and 0.80% aluminum hydroxide, respectively. It was concluded that the interfacial bonding strength was improved by the even dispersion of calcium hydroxide and aluminum hydroxide in the CR emulsion.

• 공업화학
• /
• 제16권3호
• /
• pp.361-365
• /
• 2005

$O_2$, $H_2O$, acrylic acid, diaminocyclohexane 등의 저온 플라즈마를 이용하여 시멘트 보강용 탄소 섬유 표면을 친수성으로 개질한 다음, 이에 대한 효과를 살펴보았다. 물과의 접촉각이 $75{\sim}80^{\circ}$ 정도로 소수성이던 표면이 친수성으로 변하여 접촉각이 $10^{\circ}$ 이하로까지 낮아졌으며, 이에 따라 흡습성 및 수용액에서 분산성이 크게 향상되었다. 또한, 섬유표면의 제타 포텐셜이 변하여 시멘트와 정전기적 인력이 향상됨으로써 시멘트의 결착도 향상과 함께 시멘트와의 결합이 57~124%까지 향상되었다.

• Environmental Engineering Research
• /
• 제14권4호
• /
• pp.220-225
• /
• 2009

The water quality in eutrophic lakes is affected by serious problems, such as abnormal increasing of Cyanobacteria. The purpose of this study was to investigate the possibility of a modified flotation system using a hybrid technique formed by chemical compounds and an electrostatic bridge. Therefore, experiments using the hybrid technique were performed to measure the zeta potential value on the phytoplankton surface and the removal efficiencies of phytoplankton, ammonia nitrogen, nitrate nitrogen and phosphoric acid. The results were as follows: Firstly, the zeta potential of M.aeruginosa was observed to approach charge neutralization due to adhesion of magnesium hydroxide precipitate on the phytoplankton surface in the pH range 10.5 to 11. Secondly, the concentration of chlorophyll-a decreased from about 150 to 20${\mu}g$g/L, with a maximum removal efficiency of 84% due to coagulation with pH values higher than 10. Thirdly, the N$H_4$-N concentration was observed to decrease from 0.62 to 0.54mg-N/L (13%), and the P$O_4$-P concentration, which is a limiting factor to the formation of algae blooms, decreased from 0.27 to 0.02mg-P/L (92%). These findings suggest that the modified flotation system can be applied for the purification of the raw water of numerous lakes containing high phytoplankton populations and elevated pH.

• 청정기술
• /
• 제12권4호
• /
• pp.211-216
• /
• 2006

단면이 직사각형 형태를 갖는 마이크로채널에서 이론적인 퍼텐셜의 분포변화를 제타퍼텐셜과 수력학적 지름을 변수로 조사하였다. 그리고 종/횡(Height-Width) 비를 1, 1/2, 1/3로 변화시켜서 형태의 변화에 따른 퍼텐셜의 분포변화를 조사하였다. 이를 위하여 Comsol 사의 FEMLAB 3.0을 이용하여 전산 무사를 실시하였다. 그 결과 단면의 수력학적 지름이 감소함에 따라서 높이방향 표면이 퍼텐셜 분포에 미치는 영향이 일정한 영역까지 나타났다. 또한 단면의 중앙을 지나는 가상의 선상에서 퍼텐셜 값은 제타퍼텐셜에 정비례하여 증가하였으며, 퍼텐셜 값은 단면의 종/횡 비가 증가함에 따라서 그 기울기가 증가하였다. 그렇지만 전체적으로 보았을 때, 단면의 종/횡 비가 감소함에 따라서 전기이중층이 표면방향으로 압축되는 형태를 나타내었으며, 이는 제타퍼텐셜의 증가를 가져올 것으로 사료된다.

• 공업화학
• /
• 제30권4호
• /
• pp.453-459
• /
• 2019

본 연구에서는 coconut oil과 Tween-Span계 비이온성 혼합계면활성제를 사용하여 제조한 O/W (oil in water) 유화액의 안정성에 영향을 끼치는 인자를 평가하였다. 이를 위해 비이온성 혼합계면활성제의 HLB value와 첨가량, 균질화 속도를 변수로 설정하여 제조한 O/W 유화액의 평균액적크기, 제타포텐셜, 유화안정도지수(ESI), 열적 불안정도지수(TII) 등으로부터 유화액의 안정성을 평가하였다. 제조한 O/W 유화액의 평균액적크기는 100~200 nm의 나노에멀젼으로서 비이온성 혼합계면활성제의 첨가량 및 균질화 속도가 증가함에 따라 평균액적크기는 감소하였으며, 제타포텐셜은 증가하였다. 비이온성 혼합계면활성제의 HLB value가 6.0, 10.0, 8.0 순으로 우수하게 나타났으며, HLB value가 8.0에서 제조한 유화액의 평균액적크기는 120 nm으로 가장 작고, 제타포텐셜은 40~60 mV로 가장 크게 나타났다. ESI 및 TII를 통한 안정성 평가는 HLB value가 6.0, 10.0, 8.0 순으로 안정성이 증가하였으며, HLB value가 8.0에서의 ESI 및 TII는 각각 80% 이상과 20% 이하로 가장 우수하게 나타났다.

• 한국축산식품학회지
• /
• 제33권1호
• /
• pp.67-74
• /
• 2013

The aims of this research were to produce oil-in-water ${\beta}$-lactoglobulin/alginate (${\beta}$-lg/Al) nanoemulsions loaded with coenzyme $Q_{10}$ and to investigate the combined effects of heating temperature and alginate concentration on the physicochemical properties and encapsulation efficiency of ${\beta}$-lg/Al nanoemulsions. In ${\beta}$-lg/Al nanoemulsions production, various heating temperatures (60, 65, and $70^{\circ}C$) and alginate concentrations (0, 0.01, 0.03, and 0.05%) were used. A transmission electron microscopy was used to observe morphologies of ${\beta}$-lg/Al nanoemulsions. Droplet size and zeta-potential values of ${\beta}$-lg/Al nanoemulsions and encapsulation efficiency of coenzyme $Q_{10}$ were determined by electrophoretic light scattering spectrophotometer and HPLC, respectively. The spherically shaped ${\beta}$-lg/Al nanoemulsions with the size of 169 to 220 nm were successfully formed. The heat treatments from 60 to $70^{\circ}C$ resulted in a significant (p<0.05) increase in droplet size, polydispersity, zeta-potential value of ${\beta}$-lg/Al nanoemulsions, and encapsulation efficiency of coenzyme $Q_{10}$. As alginate concentration was increased from 0 to 0.05%, there was an increase in the polydispersity index of ${\beta}$-lg/Al nanoemulsions and encapsulation efficiency of coenzyme $Q_{10}$. This study demonstrates that heating temperature and alginate concentration had a major impact on the size, polydispersity, zeta-potential value and encapsulation efficiency of coenzyme $Q_{10}$ in ${\beta}$-lg/Al nanoemulsions.

• 한국재료학회:학술대회논문집
• /
• 한국재료학회 2011년도 춘계학술발표대회
• /
• pp.34.2-34.2
• /
• 2011

The demand for Ru has been increasing in the electronic, chemical and semiconductor industry. Chemical mechanical planarization (CMP) is one of the fabrication processes for electrode formation and barrier layer removal. The abrasive particles can be easily contaminated on the top surface during the CMP process. This can induce adverse effects on subsequent patterning and film deposition processes. In this study, a post Ru CMP cleaning solution was formulated by using sodium periodate as an etchant and citric acid to modify the zeta potential of alumina particles and Ru surfaces. Ru film (150 nm thickness) was deposited on tetraethylorthosilicate (TEOS) films by the atomic layer deposition method. Ru wafers were cut into $2.0{\times}2.0$ cm pieces for the surface analysis and used for estimating PRE. A laser zeta potential analyzer (LEZA-600, Otsuka Electronics Co., Japan) was used to obtain the zeta potentials of alumina particles and the Ru surface. A contact angle analyzer (Phoenix 300, SEO, Korea) was used to measure the contact angle of the Ru surface. The adhesion force between an alumina particle and Ru wafer surface was measured by an atomic force microscope (AFM, XE-100, Park Systems, Korea). In a solution with citric acid, the zeta potential of the alumina surface was changed to a negative value due to the adsorption of negative citrate ions. However, the hydrous Ru oxide, which has positive surface charge, could be formed on Ru surface in citric acid solution at pH 6 and 8. At pH 6 and 8, relatively low particle removal efficiency was observed in citric acid solution due to the attractive force between the Ru surface and particles. At pH 10, the lowest adhesion force and highest cleaning efficiency were measured due to the repulsive force between the contaminated alumina particle and the Ru surface. The highest PRE was achieved in citric acid solution with NaIO4 below 0.01 M at pH 10.

• Membrane and Water Treatment
• /
• 제9권1호
• /
• pp.33-42
• /
• 2018

Microscopic examination of the activated sludge and morphological characterization of the flocs provides detailed information about the treatment process. The aim of this study is to investigate the morphological parameters of flocs obtained from a thermophilic jet loop membrane bioreactor (JLMBR) in different sludge retention times (SRTs), considering EPS and SMP concentration, hydrophobicity, zeta potential. The results showed that irregularity decreased with the increasing SRT. The compactness value was calculated to be less than 1 for all SRTs. However, the sludge had a more compact structure when the SRT increased. Zeta potential increased whereas hydrophobicity and floc size reduced, with increasing SRT. Furthermore, 2-D porosity calculated using the hole ratio was higher at greater SRTs. Hence, there was a significant correlation between the results obtained using the imaging technique and operation conditions of thermophilic JLMBR.

• 공업화학
• /
• 제20권1호
• /
• pp.9-14
• /
• 2009

양쪽성 계면활성제는 등전점 이하의 pH 조건에서 양이온 계면활성제로 작용함으로써 유연력을 나타낼 수 있으며, 등전점 이상의 pH 조건에서는 음이온 혹은 비이온 계면활성제로 작용하여 세정력을 나타낼 수 있다. 따라서 pH에 따른 양쪽성 계면활성제의 특성을 활용하면 한 종류의 계면활성제 분자로 세정력과 유연력을 동시에 발휘할 수 있다. 본 연구에서는 amine oxide 양쪽성 계면활성제에 대하여 계면활성제의 기본적인 물성(임계 마이셀 농도, 표면장력, 계면장력, 접촉각, 점도, 계면활성제 시스템의 상거동 등)을 측정하였으며, 또한 계면활성제 수용액에 대하여 zeta potential 측정과 QCM 실험을 통하여 양쪽성 계면활성제가 양이온 계면활성제에서 음이온 혹은 비이온 계면활성제로 작용이 전환되는 등전점을 결정하였다. 본 실험에서 사용한 amine oxide 양쪽성 계면활성제의 등전점은 7.35와 7.4인 것을 각각 zeta potential 측정과 QCM 실험을 통하여 확인할 수 있었으며, 이 결과는 문헌에 보고된 값과 유사한 결과를 나타냄을 알 수 있었다.

• 한국분말재료학회지
• /
• 제16권3호
• /
• pp.217-222
• /
• 2009

This paper presents a novel single-step method to prepare the Ag nanometallic particle dispersed fluid (nanofluid) by electrical explosion of wire in liquid, deionized water (DI water). X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM) and transmission electron microscope (TEM) were used to investigate the characteristics of the Ag nanofluids. Zeta potential was also used to measure the dispersion properties of the as-prepared Ag nanofluid. Pure Ag phase was detected in the nanofluids using water. FE-SEM analysis shows that the size of the particles formed in DI water was about 88 nm and Zeta potential value was about -43.68 without any physical and chemical treatments. Thermal conductivity of the as-prepared Ag particle dispersed nanofluid shows much higher value than that of pure DI water.