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Choi, Hyeon-gyu,Son, Moon,Choi, Heechul Elsevier 2017 CHEMOSPHERE - Vol.185 No.-
<P><B>Abstract</B></P> <P>Thin-film composite mixed matrix membrane (TFC MMM) with functionalized carbon nanotube (fCNT) blended in polyethersulfone (PES) support layer was synthesized via interfacial polymerization and phase inversion. This membrane was firstly tested in lab-scale integrating seawater desalination and wastewater reclamation forward osmosis (FO) process. Water flux of TFC MMM was increased by 72% compared to that of TFC membrane due to enhanced hydrophilicity. Although TFC MMM showed lower water flux than TFC commercial membrane, enhanced reverse salt flux selectivity (RSFS) of TFC MMM was observed compared to TFC membrane (15% higher) and TFC commercial membrane (4% higher), representing membrane permselectivity. Under effluent organic matter (EfOM) fouling test, 16% less normalized flux decline of TFC MMM was observed compared to TFC membrane. There was 8% less decline of TFC MMM compared to TFC commercial membrane due to fCNT effect on repulsive foulant–membrane interaction enhancement, caused by negatively charged membrane surface. After 10 min physical cleaning, TFC MMM displayed higher recovered normalized flux than TFC membrane (6%) and TFC commercial membrane (4%); this was also supported by visualized characterization of fouling layer. This study presents application of TFC MMM to integrated seawater desalination and wastewater reclamation FO process for the first time. It can be concluded that EfOM fouling of TFC MMM was suppressed due to repulsive foulant–membrane interaction.</P> <P><B>Highlights</B></P> <P> <UL> <LI> TFC MMM was synthesized with fCNT-blended PES layer. </LI> <LI> TFC MMM was firstly applied to integrating seawater desalination & wastewater reclamation FO process. </LI> <LI> Performances of TFC MMM were enhanced in FO test. </LI> <LI> EfOM fouling resistance was enhanced for TFC MMM due to electrostatic repulsion. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Effects of Salts on Rheological Behaviour of Salvia Hydrogels
Yudianti, Rike,Karina, Myrtha,Sakamoto, Masahiro,Azuma, Jun-ichi The Polymer Society of Korea 2009 Macromolecular Research Vol.17 No.5
Rheological behavior of natural hydrogel produced from seeds of three Salvia spp. (S. miltiorrhiza (SM), S. sclarea (SS), S. viridis (SV)) was investigated by using a Rheometer equipped with a cone and plate geometry measuring system under never-dried condition. Different chemical contents of such hydrogels give significant effects on their rheological properties. Because of incomplete penetration of water inside the hydrogels after drying before-dried hydrogels were used for rheological analysis. To know molecular interactions which predominated in the gel formation, some constituents were externally added to the 1.0% (w/w) hydrogel. Addition of urea to disrupt hydrogen bonds reduced 3.4-67% viscosity of the untreated hydrogels and changed viscoelastic properties from gel to liquid-like behavior. Neutral salts added to the hydrogel solution at 0.1 M also lowered the viscosity in a manner related with increase in size of cations and temperature. Changing from gel state to liquid-like state was also easily confirmed by oscillation measurement (storage, G', and loss, G", modulii) typically observed in the cases of potassium sulfate and potassium thiocyanate. Influence of pH variation on the viscosity explained that weak alkaline condition (pH 8-9) creates a higher resistance to flow due to increasingly electrostatic repulsions between negative charges ($COO^-$) Importance of calcium bridges was also demonstrated by recovery of viscosity of the hydrogels by addition of calcium after acidification. The summarized results indicate that electrostatic repulsion is a major contributor for production of hydrogel structure.
용존공기부상법(DAF)에서 충돌메커니즘의 영향요인 분석
독고석,이형집 대한상하수도학회 2002 상하수도학회지 Vol.16 No.5
In this research, the theoretical modeling of DAF which was obtained by trajectory analysis has been verified. Especially, the effects of electrostatic nature and particle size of bubble and particle (floc) was focused. To measure the electrostatic nature of bubble, zeta potential measuring setup was made in a well controlled laboratory. The effects of several operational parameters in DAF process are investigated on a system composed of batch DAF reactor, microscope and video system. The effect of pH on the removal efficiency of DAF is presented. The effect of mixing time is presented. The effect of zeta potential of floc and bubbles with the addition of coagulant is presented. It is found that all the phenomena can be explained primarily from the electrostatic nature of bubble and particle and secondarily from the effect of particle size. The findings from this research are compared and verified with the results of DAF modeling by α_bp. This research will be helpful to understand and explain the process better and possibly can be used to modify and improve the DAF process.
다단 방사형 섬유상 여재를 활용한 강우시 하수월류수 처리에 관한 연구
김희진 ( Heejin Kim ),심인태 ( Intae Shim ),김형준 ( Hyungjun Kim ),홍봉창 ( Bongchang Hong ),황태문 ( Tae-mun Hwang ) 한국수처리학회 2021 한국수처리학회지 Vol.29 No.1
A novel multi-fiber media filtration process was developed to treat pollutants in combined sewer overflow (CSO) effluents under a natural flow rate (12 m/hr). Most conventional CSO filtration processes operate in an upward flow, resulting in low filtration efficiency and high operating cost. In this multi-fiber filtration process, we used a horizontal filtration method with radial flow from the center of the multi-fiber medium. The fibers and filtration efficiencies were characterized using various techniques. The fibers exhibited a surface charge of -29.5 mV. The fibers’ filtration performance was evaluated under pilot-scale conditions (Q=22.5 ㎥/day) with mixed raw water amd final discharged water in an existing sewer treatment plant. In the pilot experiment, the average particle sizes for influent and effluent were 21.4 ㎛ and 4.45 ㎛, respectively, while the removal efficiency of BOD, COD, TOC, and SS was 82.9%, 77.9%, 50.1%, and 86.1%, respectively. These results are consistent with the sieving effects and electrostatic effects between fibers and pollutants. From these results, we can infer that this novel multi-fiber filtration process has the potential to treat CSO.