• Title/Summary/Keyword: Microbalance

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Measurement of Isoelectric Point of Betaine Zwitterionic Surfactant by QCM(Quartz Crystal Microbalance) (QCM(Quartz Crystal Microbalance)을 이용한 Betaine 양쪽성 계면활성제의 등전점 측정)

  • Kim, Ji Sung;Park, Jun Seok;Lim, Jong Choo
    • Korean Chemical Engineering Research
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    • v.47 no.1
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    • pp.31-37
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    • 2009

  • A zwitterionic surfactant shows not only detergency but also mildness effect since it shows characteristics of a nonionic or an anionic surfactant above an isoelectric point, while showing characteristics of a cationic surfactant below an isoelectric point. Therefore, a zwitterionic surfactant can serve as a dual function surfactant by a single molecule through the interconversion of cleaning and softening effects depending on pH variations of the aqueous solution. In this study, physical properties of betaine surfactant such as CMC, surface tension, interfacial tension, contact angle and viscosity were measured and phase behavior study was performed. Also dual function characteristics of betaine zwitterionic surfactant were investigated by measuring an isoelectric point using QCM(quartz crystal microbalance) and zeta potential measurement. The CMC of betaine surfactant was near $10^{-4}mol/L$ and the surface tension at CMC was about 32 mN/m. The interfacial tension between 1 wt% aqueous solution and n-decane measured by spinning drop tensiometer at pH 2~10 resulted in an increase in interfacial tension until pH 5 and a decrease with pH after 5 and equilibration time showed the similar trend with an increase in pH. The isoelectric point of betaine surfactant measured by QCM experiment was found to exist between 3.0 and 3.3, which is the same as the result determined by zeta potential measurement.

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Application of Quartz Crystal Microbalance to Understanding the Transport of Microplastics in Soil and Groundwater (토양-지하수내 미세플라스틱 거동 연구를 위한 수정진동자미세저울 기술 소개)

  • Kim, Juhyeok;Myeong, Hyeonah;Son, Sangbo;Kwon, Kideok D.
    • Korean Journal of Mineralogy and Petrology
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    • v.33 no.4
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    • pp.463-475
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    • 2020

  • Presence of microplastics in soil and groundwater has recently been reported and environmental concerns are raised as to the plastic pollution. In the subsurface environment, clay minerals and metal oxide minerals are commonly found as finely dispersed states. Because the minerals have high sorption capacities for diverse pollutants, interactions with mineral surface play an important role in the transport of microplastics in groundwater. Accordingly, environmental mineralogy investigating the interactions between microplastics and mineral surfaces is the essential research area to understand the fate and transport of microplastics in the subsurface environment. The microplastic-mineral surface research requires molecular- to nano-scale analyses to be able to probe the relatively weak interactions between them. The current report introduces a nano-scale analysis tool called quartz crystal microbalance (QCM) that can measure the sorbed/desorbed mass of nanoplastics on mineral surfaces at the level of a few nanograms (~10-9 g). This report briefly reviews the main principles in the QCM measurement and discusses applications of QCM to the environmental mineralogy research.

  • https://doi.org/10.22807/KJMP.2020.33.4.463 인용 PDF KSCI

Research Possibility of Using Quartz Crystal Microbalance for Polystyrene Nanoplastics Adsorption to SiO2 Surface (수정진동자미세저울을 활용한 폴리스티렌 나노플라스틱의 SiO2 표면흡착 연구 가능성)

  • Myeong, Hyeonah;Kim, Juhyeok;Lee, Jin-Yong;Kwon, Kideok D.
    • Korean Journal of Mineralogy and Petrology
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    • v.34 no.4
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    • pp.265-275
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    • 2021

  • Findings of microplastics and nanoplastics from diverse natural environments have increased demand for research of the fate and transport of the potentially toxic plastic particles in soils and groundwater. Weathering of microplastics would generate a significant amount of nanoplastics, but nanoplastics research is scarce because of technical difficulties in detecting nanoplastics in environments and analyzing nanoplastics adsorption to mineral surfaces. In the current study, we tested a possibility using quartz crystal microbalance (QCM) for application to nanoplastics adsorption analysis on mineral surfaces. In silica (SiO2)-packed column experiments, a measurable adsorption capacity for polystyrene nanoparticles often requires injection of unrealistically high ionic strengths or concentrated nanoplastic particles. The current test shows that QCM can measure polystyrene nanoplastics adsorbed onto SiO2 surface under the low ionic strengths and nanoplastics concentrations, where typical column experiments cannot. QCM is a promising tool for understanding the interaction between nanoplastics and mineral surfaces and thus transport of nanoplastics in soils and groundwater.

  • https://doi.org/10.22807/KJMP.2021.34.4.265 인용 PDF KSCI