Zero-Point Charge를 이용한 미세플라스틱의 응집 및 부상분리

장민호(Min-HO Jang),김미숙(Mi-Sug Kim),곽동희(Dong-Heui Kwak) 대한환경공학회 2020 대한환경공학회 학술발표논문집 Vol.2020 No.11

용해화 기법에 의한 HDPE와 LDPE의 등전점 분석

김선호 ( Sunho Kim ),송혜원 ( Hyewon Song ),김동수 ( Dong-su Kim ) 한국수처리학회 2021 한국수처리학회지 Vol.29 No.5

Solubilization technique was applied in determining the point of zero charge of HDPE and LDPE to suggest a method of removing the particles from the aquatic environment and separating different plastic types ahead of a recycling process. Since plastic, especially polyethylene has the potential to cause harm to humans and the ecosystem when broken down into small fragments and plastic particles can reach all domains of the earth through the hydrologic cycle, removing microplastics from the marine environment is crucial. The experiment was conducted to determine the surface characteristics of HDPE and LDPE by using the microplastic particles respectively to NaCl solution with different concentrations. The same amount of HCl was added to the solution to determine the point of zero charge of HDPE and LDPE. HDPE was observed to have a point of zero charge at 5.14 whereas the point of zero charge of LDPE was 5.28. It could be suggested that the pH of the solution can be controlled to 5.14 and 5.28 respectively. PE particles which are separated based on their point of zero charge are expected to be agglomerated and collected with high purity and converted into recycled raw material. Furthermore, this research is expected to contribute to studies that aim to remove other types of fine particles from unwanted places using a similar approach.

전위차적정(Potentiometric titration)기법에 의한 입자성 물질의 등전점(Point of zero charge)파악에 대한 기초 연구

한신혜 ( Shinhye Han ),김동수 ( Dong-su Kim ) 한국수처리학회 2020 한국수처리학회지 Vol.28 No.5

Potentiometric Titration was utilized in this research as an effective method to derive point of zero charge of glass and PVC which has posed threat to the environment and human when disposed and distributed in nature as a method of incineration or landfill. Since the point of zero charge of glass and PVC was presented in the opposite end of the range from pH 2 to pH 12, respectively pH 2.1 and pH 11.7, it was concluded that glass would be mostly positively charged in aqueous solution while PVC would behave the opposite. Therefore, the conclusion could be used as the basic study for preparation of pure sample that is crucial in provision of recycled product with superior quality, which can achieve not only economic benefits and eco-friendliness but also sturdy materials to be used in industries and daily lives. As an effort for deriving a flowchart of purification, flocculation and dispersion was applied while considering the relation between point of zero charge and surface charge in this research. In other words, the analysis of point of zero charge of particulate matters could lead to the possibility of separating them in colloidal state by converting pH of solution and improving the condition of recycled outputs.

전위차 적정법에 의한 수중 입자성 물질의 등전점 측정 및 이에 대한 전위 결정 이온의 영향

김동수 ( Dong-su Kim ) 한국수처리학회 2017 한국수처리학회지 Vol.25 No.3

The experimental procedure for the measurement of the point of zero charge of particulate matters in aquatic environment by acid titration was investigated using titanium oxide as the target material. The measurement of the pzc`s of inorganic oxide, hydroxide, and silicate particles was shown to be possible by potentiometric titration observing the pH variation with the addition of acid solution. The pzc of TiO₂ was determined to be around pH 4.1 and Fe³⁺ ion was verified to be its cationic potential determining ion. When ferric ion was co-existed in solution, the pzc of TiO₂ was observed to be decreased by around 0.3 unit in pH from its original value. Considering the feasibility of the potentiometric titration method for the measurement of the pzc value of particles, it was expected that its applicability will be very wide and versatile for the systematic control and treatment of the particulate matters in water.

천연흡착제를 이용한 질소와 인의 흡착에 관한 연구

박병윤 효성여자대학교 부설 한국환경위생연구소 1993 환경위생연구 Vol.3 No.1

폐수내의 요염물질을 효과적으료 제거할 수 있는 저가의 천연흡착제를 개발하기 위하여천연 zeolite, Na-zeolite, peat및 sand에 의한 NH_4^+ -N와 PO_4^-3 -P의 흡착능과 이들 재료의하전특성을 조사하였다. NH_4^+ -N의 흡착제거 효과는 zeolite와 Na-zeolite의 경우 매우 높게(80~90% ) 나타났으나peat의 경우는 매우 적은 양만을 흡착하였다. PO_4^-3 -P의 흡착제거 효과는 NH_4^+ -N의 흡착과는 반대로 peat에 다량 흡착(78~86% ) 흡착되었으나 aeolite와 Na-zeolite에는 상대적으로 적게 흡착(58~76%)되었다. PH에 따른 NH_4^+ -N와 PO_4^-3 -P의 흡착량을 조사한 결과 Zeolite의 경우는 흡착량의 차이를나타내지 않았으나 peat의 경우는 PH가 증가함에 따라 NH_4^+ -N의 흡착량은 증가하고 PO_4-^3 -P의 흡착량은 감소하였다. ZPC는 peat의 경우 pH4.5부근에서, zeolite의 경우는 pH9-10사이에서, Na-zeolite의경우는 pH 8~9 사이로 나타났다. The characteristics of suface charge of some natural adsorbents(zeolite, Na-saturated zeolite, peat, sand) and the adsorption capacities of themon NH_4^+ -N and PO_4^-3 -P were investigated for the purpose of developinglow-priced natural adsorbents for the effective elimination of pollutants in waste-water. The adsorption ratios of HH_4^+-N by zeolite and Na-zeolite(80~90% ) werevery high, but peat adsorbed only a small amount of that. On the contrary,the adsorption ratios of PO_4^-3 -P by zeolite and Na-zeolite(58-76% ) were muchlower than those by peat(78~86%) In the case of a adsorption experiment by peat, the amount of NH_4^+ -N adsor-ption increased, and that of P0_4^-3 -P adsorption decreased with increasing pHof suspension. In the case of a adsorption experiment by zeolite and Na-zeolite,the adsorption amount of NH_4^+ -N and PO_4^-s -P made no difference, accordingas the pH ranges of suspensions differed. The zero point charges of zeolite, Na-zeolite and peat were pH 9-10, pH8-9 an,6 about pH 4.5. respectively.

Surface charge characterization of nanofiltration membranes by potentiometric titrations and electrophoresis: Functionality vs. zeta potential

Rho, Hojung,Chon, Kangmin,Cho, Jaeweon Elsevier Scientific Pub. Co 2018 Desalination Vol. No.

<P><B>Abstract</B></P> <P>The surface charge properties (i.e., functionality and zeta (ζ) potential) of two nanofiltration (NF) membranes were characterized by potentiometric titrations and electrophoresis to predict the electrostatic transport at the membrane surfaces affecting their salt rejection and fouling propensities. The ζ potential was not suitable for evaluating the rejection of Na<SUP>+</SUP> (NE20 membrane=21–25%; NE70 membrane=65–70%) and Cl<SUP>−</SUP> ions (NE20 membrane=19–22%; NE70 membrane=60–63%), and the fouling propensities of organic materials in the NF membranes due to its inherent measurement inaccuracies (∆ ζ potential=−1.8×(∆ amount of desorbed organic foulants)+45.9, R<SUP>2</SUP> =0.07). The functionality accurately predicted both the rejection of NaCl and the fouling propensities of the organic materials, as the charge densities of the membranes determined by the functionality measurements (only TFC membranes are applicable) truly reflected the acid dissociation constants of the carboxylic and amine functional groups and the points of zero charge values. These results indicate that potentiometric titrations may provide valuable insights into the electrostatic transport at the membrane surface influencing the salt rejection and fouling mechanisms of the NF membranes.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Potentiometric titration gives new insights into intrinsic surface charge properties of NF membranes. </LI> <LI> The pH value of the lowest salt rejection corresponds to not the IEP but the PZC. </LI> <LI> ζ potential could not predict the ionization degree of amine functional groups. </LI> <LI> Functionality truly reflects the electrostatic transport of organic materials at membrane surfaces. </LI> </UL> </P>

Mesurement of Point of Zero Charge of Bentonite by Solubilization Technique and its Dependence of Surface Potential on pH

Dong Su Kim 대한환경공학회 2003 Environmental Engineering Research Vol.8 No.4

Sensitivity of nanoparticles’ stability at the point of zero charge (PZC)

엄하늬,김영훈 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.5

Since bare-nanoparticles (NPs) without stabilizers in aqueous phase are stabilized by electrostatic forces, pH control is easily used to influence the surface charge and hence the formation of aggregates or agglomerates. Therefore, herein, the sensitivity of bare-NPs’ stability in aqueous phase was analyzed close to the point of zero charge (PZC) using six model NPs. The results demonstrated that the sensitivity of NPs’ agglomeration/aggregation could be estimated by the diameter ratio (RD) between the primary and secondary particle sizes. Namely, if the primary particle size was almost identical to the hydrodynamic diameter (HDD), the agglomeration proceeded aggressively.

고다공성 카본 에어로젤(C-Aerogel) 표면 특성

김지혜(Ji-Hye Kim),이창래(Chang Rae Lee),정용수(Youngsoo Jeong),김양도(Yangdo Kim),김인배(In-Bae Kim) 한국표면공학회 2008 한국표면공학회지 Vol.41 No.3

The pyrolysized carbon xerogel and aerogels were prepared from the sol-gel polymerization of resorcinolformaldehyde(RF) followed by the dry process under ambient pressure and supercritical carbon dioxide condition respectively. The thermal behaviour of RF polymer xerogel was investigated with TGA analyzer to correspond with the pyrolysis process. The surface properties such as particle size, morphology and the point of zero charge of the pyrolysized porous carbon aerogels were studied for the precious metal catalyst supported media. It was found that the volume of the polymer aerogel decreased because of the significant linear shrinkage and weight loss of polymer gel during the carbonization. The point of zero charge of the carbon aerogel pyrolysized at 1050℃ under inert gas flow was about 10.

산성우에 의한 토양내의 이온 거동에 관한 연구

권영식,송승완 연세대학교 보건과학연구소 1995 보건과학논집 Vol.5 No.-