• 청정기술
• /
• 제10권2호
• /
• pp.61-72
• /
• 2004

본 연구에서는 물성, 세정성, 헹굼액의 유수분리성을 고려하여 유기용매의 종류 및 함량, 계면활성제의 종류 및 함량, 부조계면활성제/계면활성제 (cosurfactant/surfactant, A/S) 비율 등의 변수로 하여 수계/준수계 세정제를 개발하였다. 개발된 세정제들은 대부분 평균 액적크기가 10 ~ 20 nm의 미세 나노입자를 형성 하였으며, 30.2~32.5 dyne/cm의 낮은 표면장력과 낮은 점도 값을 보여 주었다. 플럭스에 대한 용해력은 계면활성제의 소수성이 증가할수록 높게 나타났으며 terpene을 함유한 세정제들이 hydrocarbon 함유 세정제와 대응 시판세정제에 비해 우수한 용해력을 보여 terpene계 세정제가 대체세정제로의 적합성을 보여주었다. 또한, 개발된 세정제들을 함유한 헹굼액은 시판세정제에 비하여 우수한 유수분리성을 보여 헹굼액의 재활용이 가능하여 경제적인 부담과 수질오염을 줄일 수 있음을 보여주었다. 그리고 이렇게 개발된 세정제를 L 전자 회사의 전자부품 생산라인 SMT(surface mount technology) 세정공정에 적용시켜 보았다. 그 결과 solder cream 제거에 있어서 에탄올, 이소프로필알콜(IPA), glycol ether과 같은 물질이 함유된 기존의 세정제에 비하여 세정성능이 2 배이상 향상되었고 생산현장에서 악취와 VOC의 문제를 해결시킬 수 있었다.

• Nuclear Engineering and Technology
• /
• 제52권3호
• /
• pp.581-588
• /
• 2020

The membrane fouling is an important problem for FO applied to the radioactive wastewater treatment. The FO fouling characteristics for simulated radioactive wastewater treatment was investigated. On-line cleaning by deionized (DI) water and external cleaning by ultrasound and HCl were applied for the fouled membrane. The effectiveness and foulant removing amount by each-step cleaning were evaluated. The membrane fouling was divided into three stages. Co(II), Sr(II), Cs(I), Na(I) were all found deposited on both active and support layers of the membrane surface, resulting in membrane surface became rougher and more hydrophobic, which increased membrane resistance. On-line cleaning by DI water recovered the water flux to 69%. HCl removed more foulants than ultrasound.

• 한국표면공학회지
• /
• 제49권6호
• /
• pp.513-520
• /
• 2016

Many surface protection methods have been developed to apply to constructional steels which have been used under severe corrosive environments. One of these methods, hot dip galvanizing is being widely used to the numerous constructional steels such as a guard rail of high way, various types of structural steel for manufacturing ship and for some other industrial fields etc.. Recently, the cost of zinc is getting higher and higher, thus, it is considered that improvement of hot dip galvanizing process to reduce the cost of production should be developed possibly. In this study, additives such as acid cleaning solution, $NH_4OH$, $Al(OH)_3$ and $H_2O_2$ were added to flux solution, and omission of water washing treatment after acid cleaning was investigated with some types of flux solutions added with some additives mentioned above. The decrement of pH by adding the acid cleaning solution could be controlled due to neutralization reaction with addition of $NH_4OH$. The flux solution added with both $NH_4OH$ and $Al(OH)_3$ exhibited nearly the same color and pH value as those of orignal flux solution with no added, and the sample dipped to the flux solution which was added with additives mentioned above indicated a relatively good corrosion resistance compared to other samples. However, the flux solution added with $NH_4OH$, $Al(OH)_3$ and $H_2O_2$ exhibited a different color, sediment and a bad corrosion resistance. Consequently, it is considered that omission of water washing treatment may be able to perform by adding optimum additives to the original flux solution.

• 분석과학
• /
• 제6권5호
• /
• pp.521-530
• /
• 1993

몬트리올의정서에 의하여 오존층 파괴물질로 규정된 전자산업의 필수불가결한 세정제인 CFC 113(1,1,2-trichloro 1,2,2,-trifluoroethane)의 사용이 앞으로 규제가 됨에 따라서 대체세정제의 개발이 활발히 진행되고 있다. 따라서 현재 시판중인 세정제의 종류는 상당히 많다. 이 중에서 Axarel 32(DuPont), Cleanthru 750H(KAO Chemical), EC-Ultra(Petroferm)를 선정하여 CFC 113과 세정성능을 비교하였다. CFC 113과 대체세정제의 세정성능 검사방법은 기본적은 물성측정, 재질호환성에 대한 실험, 증발속도의 측정, 오염물질의 제거효율에 관한 실험으로 구성되어 있다. CFC 113과 대체세정제들의 기본적인 물성들은 서로 상이하였다. 대체세정제는 비점이 높고 표면장력과 점도가 CFC 113보다 큰 값을 가지고 있다. 전자산업에서의 로진계 flux를 오염물질로 하고 각기의 세정제와의 용해도를 비교한 결과 비극성 유기물질은 abietic acid에 대한 용해도는 서로 유사하였으나 대체세정제의 경우 극성 유기물질에 대한 용해도는 CFC 113에 비해서 월등히 좋았다. 또한 비점이 낮은 CFC 113의 건조성은 대체세정제와는 비교할 수 없을 정도로 우수하였고 특히 대체세정제 중에서 EC-Ultra는 건조성이 매우 낮았다. CFC 113과 대체세정제에서의 PCB의 구성 재질인 FR4와 Cu-coated FR4에 대한 재질호환성은 거의 비슷하였다. Abietic acid의 제거효율에 관한 실험에서는 초음파 세정에 의해서 우수한 세정효과를 보여 주었으며 침적에 의해 세정에서는 건조성이 좋은 세정제가 유리하지만 초음파 세정에 의해서 대체세정제간의 제거효율의 차이는 거의 없었다. CFC 113의 대체세정제로서 로진계 flux를 제거하는 대체세정제간의 세정성능은 큰 차이는 없으나 최종 세정제로 선정하기 위해서는 세정장치의 적용, 환경문제 및 경제성의 고려가 병행되어야 한다.

• 상하수도학회지
• /
• 제24권1호
• /
• pp.93-101
• /
• 2010

Reverse osmosis (RO) membranes have been widely used for desalination as well as water and wastewater treatment facilities. Cleaning process is important to maintain stable operation as well as prevention of membrane fouling. Purpose of this research is to analyze electrostatistic and chemical characteristics after cleaning of RO membrane against $SiO_2$ scale. Four RO membranes of polyamide are used and examined about effect of chemical cleaning. EDTA (ethylene diamine tetraacetic acid) and SDS (sodium dodecil sulfate) and NaOH are applied for cleaning process after operation in synthetic water. Then, cleaning was performed with chemicals such concentration as 6hr, 12hr and 24hr, respectively. As a result, transmittances of FT-IR of four membranes are compared at each cleaning concentration. Ta/Tv shows difference of chemical composition between new membrane and cleaning membrane after cleaning. Type B of RO membrane is turned out to be most vulnerable to cleaning among four membranes. In terms of zeta potential, new membrane has -16 mV to +6 mV on pH while scaled membrane has -18 mV to 2 mV. However, it changed -23mV to 0.9 mV after cleaning. In comparison with existing salt rejection of RO membranes after cleaning, the rejection of the membranes goes down 0.7% maximum. Though cleaning changes the characteristics of membrane surface, it does not greatly affect salt rejection. pH is a critical factor to flux change in PA (polyamide) membrane.

• Membrane and Water Treatment
• /
• 제11권2호
• /
• pp.97-109
• /
• 2020

Membrane fouling is the main drawback of membrane technology. Frequent membrane cleaning and membrane replacement are, therefore, required to reduce membrane fouling that causes permeate flux reduction, lower rejection, or higher operating pressure. Studies have proved that the alteration of membrane properties is the key controlling factor in lessening membrane fouling. Among stimuli-responsive membranes, thermo-responsive membrane is the most popular, with a drastic phase transition and swelling-shrinking behavior caused by the temperature change. In this study, the thermo-responsive ability of two commercial membranes, PolyCera® Titan membrane and PolyCera® Hydro membrane, at different temperatures was studied on the antifouling function of the membrane in palm oil mill effluent (POME) treatment. The evaluation of the membrane's thermo-responsive ability was done through three cycles of adsorption (fouling) and desorption (defouling) processes in a membrane filtration process. The experimental result depicted that PolyCera® Hydro membrane had a higher membrane permeability of 67.869 L/㎡.h.bar than PolyCera® Titan membrane at 46.011 L/㎡.h.bar. However, the high membrane permeability of PolyCera® Hydro membrane was compensated with low removal efficiency. PolyCera® Titan membrane with a smaller mean pore size had better rejection performance than PolyCera® Hydro membrane for all tested parameters. On the other hand, PolyCera® Titan membrane had a better hydrodynamic cleaning efficiency than PolyCera® Hydro membrane regardless of the hydrodynamic cleaning temperature. The best hydrodynamic cleaning performed by PolyCera® Titan membrane was at 35℃ with the flux recovery ratio (FRR) of 99.17 ± 1.43%. The excellent thermo-responsive properties of the PolyCera® Titan membrane could eventually reduce the frequency of membrane replacement and lessen the use of chemicals for membrane cleaning. This outstanding exploration helps to provide a solution to the chemical industry and membrane technology bottleneck, which is the membrane fouling, thus reducing the operating cost incurred by the membrane fouling.

• Membrane and Water Treatment
• /
• 제8권2호
• /
• pp.185-199
• /
• 2017

Low-pressure membrane filtration is increasingly used for tertiary treatment of wastewater effluent organic matter (EfOM), mainly comprising organic base/neutral compounds. In-line coagulation with underdosing, charge neutralization, and sweep floc conditions prior to ultrafiltration (UF) was studied to determine removals of the EfOM components and consequent reduction of fouling using polyethersulfone membranes. Coagulation and UF substantially reduced fouling for all coagulation conditions while removing from 7 to 38% of EfOM organic acids. From 7 to 16% of EfOM organic base/neutrals were removed at neutral pH but there was no significant removal for slightly acid coagulation conditions even though fouling was substantially reduced. Sweep floc produced the lowest resistance to filtration but may be inappropriate for in-line use due to the large added volume of solids. Charge-neutralization resulted in poor recovery of the initial flux with hydraulic cleaning. Under-dosing paralleled sweep floc in reducing hydraulic resistance to filtration (for sub-critical flux) and the initial flux was also easily recovered with hydraulic cleaning. Hydrophobic and hydrophilic base/neutrals were identified on the fouled membranes but as previously reported the extent of fouling was not correlated with accumulation of organic base/neutrals.

• 한국환경과학회지
• /
• 제25권6호
• /
• pp.817-827
• /
• 2016

The resistance in series model has been frequently used for determination of various filtration resistance to correctly understand the membrane fouling behaviour in MBR (membrane bio-reactor) for wastewater treatment. The cake layer resistance ($R_c$) which is commonly determined by calculation of flux dataset that are obtained empirically before and after removing the cake layer on membrane surface. However, the calculated Rc values are very dependent on the cleaning methods adapted for removal of cake layer. This study investigated how the various cleaning options affect $R_c$. Seven different cleaning methods were employed: i) ultrasonication (100 W, 10 min), ii) ultrasonication (200 W, 60 min), iii) ultrasonication (400 W, 120 min), iv) water rinsing in a shaker (100 rpm, 10 min), v) water rinsing in a shaker (300 rpm, 60 min), vi) water rinsing, vii) sponge scrubbing. For the hydrophilic PES membrane, the cake layer removal efficiencies ranged from 64% to 10%, indicating that the removal of cake layer was highly dependent on the cleaning options. For the hydrophobic PVDF membrane, the cake layer removal efficiencies ranged from 79% to 97%. Consequently, a standardized method for cake layer removal to determine cake resistance ($R_c$) is needed for correct interpretation of the fouling phenomena.

• 한국막학회:학술대회논문집
• /
• 한국막학회 1999년도 Energy Saving Membrane Separtion Systems 에너지 절약형 막분리 시스템
• /
• pp.93-116
• /
• 1999

MF membrane element was specially designed for water purification and VSA process which can solve the fouling problem. Especially VSA process is developed for the SK Chemicals' asymmetric microfiltration hollow fiber membranes. In case of outside-to-in filtration process, MF membrane element showed the excellent flux stability caused by cleaning ability of VSA process . Simultaneous back-washing with VSA consideratbly enhances cleaning efficiency. From the result the possibility of the replacement of chemical coagulation and sand filtration process with newly developed VSA process was revealed.

• 한국막학회:학술대회논문집
• /
• 한국막학회 1999년도 The 7th Summer Workshop of the Membrane Society of Korea
• /
• pp.63-66
• /
• 1999

MF membrane element was specially designed for water purification and VSA process which can solve the fouling problem. Especially VSA process is developed for the SK Chemical's asymmetric microfiltration hollow fiber membranes. In case of outside-to-in filtration process, MF membrane element showed the excellent flux stability caused by cleaning ability of VSA process. Simultaneous back- washing with VSA considerably enhances cleaning efficiency. Form the result, the possibility of the replacement of chemical coagulation and sand filtration process with newly developed VSA process was revealed.