Capillarity ion concentration polarization as spontaneous desalting mechanism

Park, Sung Min; Jung, Young Bok; Son, Seok Young; Cho, Inhee; Cho, Youngrok; Lee, Hyomin; Kim, Ho-Young; Kim, Sung Jae

doi:10.1038/ncomms11223

Cited by 40 publications

(27 citation statements)

References 45 publications

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“…Therefore, the width of hydrogel was almost unchanged at pH = 3.5, while it expanded by 23% after 1 h in the solution of pH = 5.5 as shown in Figure 6a. When the swollen hydrogel blocked a microchannel, the configuration of microchannel was changed into micro-nano-micro-connection because the hydrogel possesses a number of nanopores inside [26,29,51]. Consequently, one can expect ICP phenomenon with the swollen hydrogel.…”

Section: Nanofluidic Sensing Of Ph Stimulationmentioning

confidence: 99%

“…Since the ion depletion zone in ICP acts as an electrical filter together with zero-Reynolds number characteristics, it has been actively utilized for low abundance biomolecular separation / accumulation device [21][22][23]. If one can extract the solution from the ion depletion zone, one can use it as portable scale electro-desalination / purification [1,[24][25][26][27] device. However, shared fundamental aspects of ICP and CP have been actively studied such as vortex generation [9][10][11]28], stabilization [17,[29][30][31], mechanism of overlimiting current [12][13][14]16,18,20], phenomenon near nanopores [32][33][34][35] and concentration profile including pH variation [36][37][38], etc.…”

Section: Introductionmentioning

confidence: 99%

“…The ability to manipulate pH change provides great opportunities to integrate ICP applications with bio/chemical reaction or analysis requiring rapid pH change. For example, precise pH control is highly demanded in ICP desalination device because it produces drinking water [1,26,39]. Other crucial examples are biological applications.…”

Section: Introductionmentioning

confidence: 99%

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Controllable pH Manipulations in Micro/Nanofluidic Device Using Nanoscale Electrokinetics

Park

Kim

2020

Micromachines

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Recently introduced nanoscale electrokinetic phenomenon called ion concentration polarization (ICP) has been suffered from serious pH changes to the sample fluid. A number of studies have focused on the origin of pH changes and strategies for regulating it. Instead of avoiding pH changes, in this work, we tried to demonstrate new ways to utilize this inevitable pH change. First, one can obtain a well-defined pH gradient in proton-received microchannel by applying a fixed electric current through a proton exchange membrane. Furthermore, one can tune the pH gradient on demand by adjusting the proton mass transportation (i.e., adjusting electric current). Secondly, we demonstrated that the occurrence of ICP can be examined by sensing a surrounding pH of electrolyte solution. When pH > threshold pH, patterned pH-responsive hydrogel inside a straight microchannel acted as a nanojunction to block the microchannel, while it did as a microjunction when pH < threshold pH. In case of forming a nanojunction, electrical current significantly dropped compared to the case of a microjunction. The strategies that presented in this work would be a basis for useful engineering applications such as a localized pH stimulation to biomolecules using tunable pH gradient generation and portable pH sensor with pH-sensitive hydrogel.

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Section: Nanofluidic Sensing Of Ph Stimulationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Controllable pH Manipulations in Micro/Nanofluidic Device Using Nanoscale Electrokinetics

Park

Kim

2020

Micromachines

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“…Our previous work presented the spontaneous preconcentration (or selective preconcentration) method in microfluidic chip with leveraging convective flow through microchannel over diffusiophoresis induced by imbibition and ion exchange of ion exchange medium, respectively [13][14][15][16][17][18]. Especially, we had demonstrated that the velocity of the convective flow by the imbibition of the medium deviated from original Darcy's law using non-uniformly patterned ion exchange medium, but this work has the limitation of time-consuming and complex process [13].…”

Section: Introductionmentioning

confidence: 99%

Spontaneous diffusiophoretic separation in paper-based microfluidic device

Lee

Kim

2020

Micro and Nano Syst Lett

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Microfluidic paper-based analytical devices (μPADs) for separating particles have been playing a key role for point-ofcare diagnostics in the area of remote settings. While splendid separation methods using μPADs have been explosively developed, they still require external devices inducing external field. In this work, the spontaneous separation method in μPADs was suggested by leveraging convective flow (the imbibition of paper and nanoporous medium) and diffusiophoresis by ion exchange medium. Especially, the paper's fast imbibition was utilized as driving particles at the first stage, which results in fast overall processing in contrast to the spontaneous separation method of microfluidic chip integrated with only ion exchange medium. Therefore, our novel spontaneous selective preconcentration method based on μPADs would have key potential to be used in portable point-of-care devices in remote settings.

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“…It is still a challenge to prepare high efficiency, reusable and broad-spectrum adsorbents. Recently, polymeric hydrogels have been considered as high performance materials for environmental applications such as desalination 30 , heavy metal ions removal 31 and radionuclides 32 due to their advantageous characteristics including adsorption-regeneration ability, economic feasibility, and environmental compatibility. However, there are few of studies on the removal of dyes using polymeric hydrogels.…”

Section: Introductionmentioning

confidence: 99%

Polyacrylamide-Phytic Acid-Polydopamine Conducting Porous Hydrogel for Efficient Removal of Water-Soluble Dyes

Zhang

Geleta

2017

Sci Rep

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Removal of toxic dyes from wastewater has become a hot topic in both academic and industrial fields since there is growing concern about the threat of sewage to human health. Herein, we demonstrate that the three-dimensional porous polyacrylamide-phytic acid-polydopamine (termed as PAAM/PA/PDA) hydrogel can be served as reusable adsorbent with high efficiency for either anionic or cationic dyes. Using methyl blue (MB), methylene blue (YMB), methyl violet (MV) and neutral red (NR) as model dyes, we investigate the effect of pH, temperature, dye concentration, and PAAM/PA/PDA hydrogel mass on the adsorption. The experimental maximum adsorption capacities are more than 350.67 mg g−1 for four selected dyes. Adsorption kinetic and thermodynamic analysis suggests that the dyes are adsorbed on the PAAM/PA/PDA hydrogel through the strong π-π stacking and anion-cation interaction, and the adsorption process satisfies a pseudo-second-order model. Furthermore, the free-standing PAAM/PA/PDA hydrogel can be easily removed from water after adsorption process, and regenerated by adjusting solution pH values.

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Capillarity ion concentration polarization as spontaneous desalting mechanism

Cited by 40 publications

References 45 publications

Controllable pH Manipulations in Micro/Nanofluidic Device Using Nanoscale Electrokinetics

Controllable pH Manipulations in Micro/Nanofluidic Device Using Nanoscale Electrokinetics

Spontaneous diffusiophoretic separation in paper-based microfluidic device

Polyacrylamide-Phytic Acid-Polydopamine Conducting Porous Hydrogel for Efficient Removal of Water-Soluble Dyes

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