• Advances in nano research
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• 제3권4호
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• pp.243-255
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• 2015

In this investigation, ecotoxicity of nano and micro metal oxides, namely silica ($SiO_2$) and alumina ($Al_2O_3$), on the growth of green algae (Porphyridium aerugineum Geitler) is discussed. Effects of nano and micro particles on the growth, chlorophyll content and protein content of algae are analysed using standard protocols. Results indicate that $SiO_2$ nano and micro $SiO_2$ particles are non-toxic to P. aerugineum Geitler up to a concentration of 1000 mg/L. In addition, $Al_2O_3$ microparticles are less toxic to P. aerugineum Geitler, whereas $Al_2O_3$ nanoparticles are found to be highly toxic at 1000 mg/L. Moreover, $Al_2O_3$ nanoparticles decrease the growth, chlorophyll content, and protein content of tested algae. In addition, zeta potential and contact angle are also important in enhancing the toxicity of metal oxide nanoparticles in aquatic environment. This study highlights a new insight into toxicity evaluation of nanoparticles on beneficial aquatic organisms such as algae.

• 한국세라믹학회지
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• 제27권1호
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• pp.109-117
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• 1990

Magnetite for Water-based ferrofluid was synthesized by air oxidation of aqueous suspension in the pH range 7-12 at $65^{\circ}C$. The optimum condition of magneite formation was delineated by examining various physicochemcial properties such as Fe2+ content, phase characteristics, MHC and $\sigma$max. The point of zero charge of iron oxide powders obtained at various pH conditions were correlated with the oxidation state of Fe in the iron oxide. The magnetite powder prepared at pH 9 ws dispersed using sodium oleate and sodium dodecylbenzenesulfonate (SDBS) as dispersants, and the dispersion characteristics of the magnetite ferrofluid were examined by means of the fraction of solid dispersed, zeta potential data and FT-IR spectrum. A simple calculation on the potential energy of two interacting magnetite particles showed that the dispersion stability was directly correlated with height of the potential energy barrier or the shape of zeta potential.

• 공업화학
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• 제20권1호
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• pp.9-14
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• 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.

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

• 상하수도학회지
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• 제22권6호
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• pp.689-696
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• 2008

In a water treatment process a complete and homogeneous dispersion of the coagulants in the raw water could be most important factor. This research was performed to evaluate coagulation performance of the in-line-orifice mixer which was recently introduced as a rapid mixing device. The test was to determine the actual coagulant dispersion distribution on the overall cross-section at a distance of 1.6~3D from the chemical injection point by measuring zeta potential. From the results of zeta potential test, it was shown that the coagulant dispersion within the in-line orifice mixer was occurred very unevenly. The results have confirmed that it is necessary to increase the velocity of coagulants injection or pressurized water rates, in order to reduce nonuniform distribution of chemicals.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2021년도 봄 학술논문 발표대회
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• pp.110-111
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• 2021

The eggshell is a type of bio-waste which is considered hazardous to the environment. In this research, the waste eggshell is utilized as a potential filler in cementitious material. This study has measured by zeta potential to analyze the interaction between the surface of the filler and the calcium ion in the solution. Meanwhile, the effect of eggshell powder on cement hydration process has been determined by isothermal calorimeter. The results show that the surface of eggshell powder have a strong adsorption of Ca2+, and addition of the eggshell powder provides a heterogeneous nucleation site for cement, which promotes the growth of hydration products.

• 한국의류학회지
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• 제34권7호
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• pp.1175-1183
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• 2010

This study investigates the effect of polarity of oily soil on adhesion of oily and particulate soil to PET fabric in oily/particulate mixed soil systems. The potential energy of interaction between two particles was examined as a fundamental environment of adhesion of soil to fabrics. The ${\zeta}$-potential of ${\alpha}-Fe_2O_3$ particles was measured by a microelectrophoresis method, and the potential energy of interaction between two particles was calculated by using the Verwey-Overbeek theory. The ${\zeta}$-potential of particle and the potential energy of interaction between two particles was slightly influenced by the polarity and type of oily soil, but increased with the increased anionic surfactant concentration and amount of oily soil. The adhesion of oily soil to fabric increased with the additional amount of polarity of oily soil and decreased surfactant concentration that was relatively high at a temperature of $60^{\circ}C$ surfactants solution. The adhesion of ${\alpha}-Fe_2O_3$ particle to PET fabric decreased with an increased amount and polarity of oily soil and increased surfactant concentration Although some similarity exists, the general trend of the adhesion to fabric by particulate soil differ from oily soil.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2001년도 춘계학술발표강연 및 논문개요집
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• pp.54-54
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• 2001

• 한국의류산업학회지
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• 제3권1호
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• pp.1-8
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• 2001

• 한국세라믹학회지
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• 제36권12호
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• pp.1281-1286
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• 1999