• Journal of Korean Society of Environmental Engineers
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• v.22 no.12
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• pp.2227-2238
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• 2000

The interfacial features of suspension system made of $CaCO_3$ particles have been investigated for the purpose of designing its effective treatment process. For the examination of variation of electrokinetic potential as a function of pH. the value of potential was observed to shift in the negative direction, which was thought to be due to the adsorption of hydroxide ion on the particle surface. Adsorption of surfactant on suspended particles resulted in the change of surface charge and shift in electrokinetic potential, which was dependent upon the sign of head charge and concentration of surfactant. Addition of inorganic salts affected stability of suspension greatly and sedimentation rate of suspension was influenced by the electric valence and amount of ions produced by dissolution of inorganic coagulants. DLVO theory made it possible to construct a energy profile diagram and a close correlation was found between experimental result and theoretically derived consequences. Non-specific adsorption of indifferent electrolyte resulted in the compression of electrical double layer and specific adsorption induced the shift of IEP and PZC in the opposite direction.

• Bulletin of the Korean Chemical Society
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• v.25 no.8
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• pp.1182-1188
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• 2004

Polydisperse oligo(PO-b-EO) allyl ether siloxane surfactants were synthesized by the hydrosilylation reaction of OMTS with Allyl-oligo(PO-b-EO) series. The surface tension of siloxane surfactants increased with increasing the EO chain length while it decreased with increasing the PO ratio. However, the sedimentation time of the aqueous solution showed opposite trend to the surface tension data. Both the surface tension and sedimentation time of the aqueous solution containing inorganic electrolyte gradually decreased as the content of inorganic electrolyte increased because of the surface arrangement of surfactant molecules. However, they increased with an increase of pH values due to the hydrolysis of the siloxane backbone. The $C_p$ values tended to increase with the increase in the EO chain length and decrease of the PO ratio. It seems that intermolecular interaction between PO/EO block copolymer and water affects the variation of transition temperature.

• Environmental Engineering Research
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• v.10 no.3
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• pp.138-143
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• 2005

Laboratory batch experiments were conducted to evaluate the Fenton degradation rates of phenanthrene. Fenton reactions for the degradation of phenanthrene were carried out with aqueous and slurry phase, to investigate the effects of sorption of phenanthrene onto solid phase. Various types of surfactants and electrolyte solutions were used to evaluate the effects on the phenanthrene degradation rates by Fenton's reaction. A maximum 90% removal of phenanthrene was achieved in aqueous phase with 0.9% of $H_2O_2$ and 300 mg/L of $Fe^{2+}$ at pH 3. In aqueous phase reaction, inhibitory effects of synthetic surfactants on the removal of phenanthrene were observed, implying that surfactant molecules acted as strong scavenger of hydroxyl radicals. However, use of $carboxymethyl-{\beta}-cyclodextrin$ (CMCD), natural surfactant, showed a slight enhancement in the degradation of phenanthrene. It was considered that reactive radicals formed at ternary complex were located in close proximity to phenanthrene partitioned into CMCD cavities. It was also show that Fenton degradation of phenanthrene were greatly enhanced by addition of NaCl, indicating that potent radical ion ($OCI^-$) played an important role in the phenanthrene degradation, although chloride ion might be acted as scavenger of radicals at low concentrations. Phenanthrene in slurry phase was resistant to Fenton degradation. It might be due to the fact that free radicals were mostly reacting with dissolved species rather than with sorbed phenanthrene. Even though synthetic surfactants were added to increase the phenanthrene concentration in dissolved phase, low degradation efficiency was obtained because of the scavenging of radicals by surfactants molecules. However, use of CMCD in slurry phase, showed a slight enhancement in the phenanthrene degradation. As an alternative, use of Fenton reaction with CMCD could be considered to increase the degradation rates of phenanthrene desorbed from solid phase.

• Bulletin of the Korean Chemical Society
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• v.26 no.10
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• pp.1560-1564
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• 2005

The influence of cetyltrimethylammonium bromide (CTAB) on the electrochemical behavior of bisphenol A at the carbon paste electrode (CPE) was investigated. CTAB, with a hydrophobic C-H chain, can adsorb at the CPE surface via hydrophobic interaction and then change the electrode/solution interface, and finally affects the electrochemical response of bisphenol A, confirming from the remarkable oxidation peak current enhancement. The electrode process of bisphenol A was examined, and then all the experimental parameters which affects the electrochemical response of bisphenol A, such as pH value of the supporting electrolyte, accumulation potential and time, potential scan rate and the concentration of CTAB, were examined. Finally, a sensitive and simple voltammetric method was developed for the determination of bisphenol A. Under the optimum conditions, the oxidation peak current of bisphenol A varied linearly with its concentration over the range from $2.5\;{\times}\;10^{-8}\;to\;1\;{\times}\;10^{-6}$ mol/L, and the detection limit was found to be $7.5\;{\times}\;10^{-9}$ mol/L. This method was successfully employed to determine bisphenol A in some waste plastic samples.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.379-382
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• 2006

We are investigating the effect of particle on electrowetting, and this paper reports the experimental results obtained until now. The experiment was performed for different particle sizes, electrolyte concentration, and AC frequencies. The problem is quite complicated by various factors, such as the existence of surfactant in suspension and sedimentation of particles. We could not draw a concrete conclusion on the effect of particles, and it needs further investigations. We also report interesting phenomena observed during the experiment. It includes the droplet generation at the edge of a droplet, pseudo-bistability of electrowetting, flow generation inside a droplet, and the chain formation of particles inside a droplet.

• Applied Chemistry for Engineering
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• v.24 no.2
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• pp.121-125
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• 2013

In this work, we prepared the carbon paper from chopped carbon fibers using a gas diffusion matrix in polymer electrolyte membrane fuel cells by wet processing. The process of making carbon paper using wet processing is consisted of the three steps involving the dispersion of chopped carbon fibers, the preparation of the carbon fiber web, the impregnating of phenol resin. This work was focused on finding the optimal surfactant to make the carbon paper with 2D orientation of carbon fibers by investigating the dispersion state of carbon fibers in different dispersion solutions. Furthermore, the effect of phenol resin and carbon black contents on properties of electric conductivity was analyzed. As a result, it is confirmed that the carbon fiber was well dispersed when using sodium dodecyl sulfate as a surfactant, and the carbon paper with 8 wt% of phenol and 5 wt% of carbon black contents showed the most excellent electrical property.

• Journal of Soil and Groundwater Environment
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• v.9 no.1
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• pp.54-62
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• 2004

In order to enhance the efficiency of removal a series of ElectroKinetic Remediation (EKR) tests on ferrous soil contaminated by lead are carried out using acids, chelates and surfactant as flushing agents. The test results indicate that pH in the electrolyte rapidly reached at steady state as the introduce of flushing solution of the lower pH, the type of flushing solution have no effect the distribution of electrical voltage within the sample but the increasing of solution concentration increases it at x/L=0.9. In the distribution of the residual lead in the sample SDS is the highest. Also, the removal efficiency for acetic acid concentration of 1mM Is the highest but the concentration of acetic acid significantly have no effect.

• Journal of the Korean Electrochemical Society
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• v.26 no.4
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• pp.71-79
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• 2023

In this study, we employed anionic, cationic, and nonionic surfactants for the hydrophilization of porous substrates used in the fabrication of pore-filling membranes. We investigated the extent of hydrophilization based on the type of surfactant, its concentration, and immersion time. Furthermore, we used the hydrophilized substrates to produce pore-filling anion exchange membranes and compared their ion conductivity to determine the optimal hydrophilization conditions. For the ionic surfactants used in this study, we observed that hydrophilization progressed rapidly from the beginning of immersion when the applied concentration was 3.0 wt%, compared to lower concentrations (0.05, 0.5, and 1.0 wt%). In contrast, for the relatively larger molecular weight non-ionic surfactants, smooth hydrophilization was not observed. There was no apparent correlation between the degree of hydrophilization and the ion conductivity of the anion exchange membrane. This discrepancy suggests that an excessive hydrophilization process during the treatment of porous substrates leads to excessive adsorption of the surfactant on the sparse surfaces of the porous substrate, resulting in a significant reduction in porosity and subsequently decreasing the content of polymer electrolyte capable of ion exchange, thereby greatly increasing the electrical resistance of the membrane.

• Resources Recycling
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• v.20 no.4
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• pp.52-57
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• 2011

Present paper reports a new method to separate the electrolyte membranes and carbon paper without using ultrasonic waves and stirring. In this method, these were separated from fuel cell membrane-electrode assembly(MEA) using the distilled water, butanol and surfactant by dipping method without the dispersion of catalyst particles. Separated carbon paper catalysts and fuel cell Pt/C catalysts were heated in aqua regia at $80{\sim}85^{\circ}C$ and added to precipitant. After calcination, Pt metal was recovered which might be used in fabricating new fuel cells.

• Applied Chemistry for Engineering
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• v.23 no.2
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• pp.131-137
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• 2012

Polyaniline (PANI) and polypyrrole (Ppy) hollow sphere structures with controlled shell thicknesses can be easily synthesized than those of using a layer-by-layer method for cathode active material of lithium-ion batteries. Polystyrene (PS) core was synthesized by emulsion polymerization using an anion surfactant. The shell thicknesses of PANI and Ppy were controlled by amounts of aniline and pyrrole monomers. PS was removed by an organic solution. This structure increased in contact with an electrolyte and a specific capacity in lithium-ion batteries. But polymers have disadvantages such as the difficult control of molecular weights and low densities. These disadvantages were completed by controlled shell thicknesses. The amount of aniline monomer increased from 1.2, 2.4, 3.6, 4.8 to 6.0 mL, and the shell thicknesses were 30.2, 38.0, 42.2, 48.2, and 52.4 nm, respectively. And the amount of pyrrole monomer was 0.6, 1.2, 2.4 and 3.6 mL, the shell thicknesses were 16.0, 22.0, 27.0 and 34.0 nm, respectively. In the cathode materials with controlled shell thicknesses, shell thicknesses of the PANI hollow spheres were 30.2, 42.2, and 52.4 nm, and discharge specific capacities of after 10 cycle were ~18, ~29, and ~62 mAh/g, respectively. The shell thicknesses of the Ppy hollow spheres were 16.0, 22.0, 27.0 and 34.0 nm, and discharge specific capacities of after 15 cycle were ~15, ~36, ~56, and ~77 mAh/g, respectively. Thus, shell thicknesses of PANI and Ppy increased, the specific capacities increased.