• Korean Chemical Engineering Research
• /
• v.50 no.2
• /
• pp.379-384
• /
• 2012

It is investigated that that the physical properties of Glutathione layer formed on gold surfaces may make an effect on the distribution of either gold particle adsorbed to the $TiO_2$ surface or vice versa with the adjustment of the electrostatic interactions. For the investigation, the atomic force microscope (AFM) was used to measure the surface forces between the surfaces as a function of the salt concentration and pH value. With the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory, the forces were quantitatively analyzed to acquire the surface potential and charge density of the surfaces for each salt concentration and each pH value. The surface potential and charge density dependence on the salt concentration was described with the law of mass action, and the pH dependence was explained with the ionizable groups on the surface. The salt concentration dependence of the surface properties, found from the measurement at pH 8 and 11, was consistent with the prediction from the law. It was found that the Glutathione layer had higher values for the surface charge densities and potentials than the titanium dioxide surfaces at pH 8 and 11, which may be attributed to the ionized-functional-groups of the Glutathione layer.

• Clean Technology
• /
• v.20 no.2
• /
• pp.130-135
• /
• 2014

It is investigated that the surface properties of mercaptopyruvic-acid layer formed on gold surfaces may make an effect on the distribution of either gold particle adsorbed to the zirconia surface or vice versa. For the investigation, the atomic force microscope was used to measure the surface forces between the surfaces as a function of the salt concentration and pH value. The forces were quantitatively analyzed with the derjaguin-landau-verwey-overbeek (DLVO) theory to estimate the electrostatic properties, potential and charge density, of the surfaces for each condition of salt concentration and pH value. The estimatedvalue dependence on the salt concentration was explained with the law of mass action, and the pH dependence was interpreted with the ionizable groups on the surface. The salt concentration dependence of the surface properties, found from the measurement at pH 4 and 8, was predictable from the law. It was found that the mercaptopyruvic-acid layer had higher values for the surface charge densities and potentials than the zirconia surfaces at pH 4 and 8, which may be attributed to the ionizedfunctional-groups of the mercaptopyruvic-acid layer.

• Korean Journal of Materials Research
• /
• v.24 no.1
• /
• pp.6-12
• /
• 2014

In the present work, $WO_3$ and $WO_3-TiO_2$ were prepared by the chemical deposition method. Structural variations, surface state and elemental compositions were investigated for preparation of $WO_3-TiO_2$ sonocatalyst. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) and transmission electron microscopy (TEM) were employed for characterization of these new photocatalysts. A rhodamine B (Rh.B) solution under ultrasonic irradiation was used to determine the catalytic activity. Excellent catalytic degradation of an Rh.B solution was observed using the $WO_3-TiO_2$ composites under ultrasonic irradiation. Sonocatalytic degradation is a novel technology of treating wastewater. During the ultrasonic treatment of aqueous solutions sonoluminescence, cavitaties and "hot spot" occurred, leading to the dissociation of water molecules. In case of a $WO_3$ coupled system, a semiconductor coupled with two components has a beneficial role in improving charge separation and enhancing $TiO_2$ response to ultrasonic radiations. In case of the addition of $WO_3$ as new matter, the excited electrons from the $WO_3$ particles are quickly transferred to $TiO_2$ particle, as the conduction band of $WO_3$ is 0.74 eV which is -0.5 eV more than that of $TiO_2$. This transfer of charge should enhance the oxidation of the adsorbed organic substrate. The result shows that the photocatalytic performance of $TiO_2$ nanoparticles was improved by loading $WO_3$.

• The Journal of the Petrological Society of Korea
• /
• v.26 no.2
• /
• pp.143-152
• /
• 2017

As weathering processes, micro-cavities are formed on the surface of rocks, and in particular, the porous structure is increased in feldspar. Adsorption and antibacterial tests were carried out to clarify the environmental function of porous feldspar porphyry. Almost all the heavy metals were adsorbed in the feldspar filter and the adsorption rate could be controlled by changing the filter length. The shake flask method of fabric coated with 5% and 7% feldspar powder showed very high antibacterial activity of 98% and 99.9%, respectively. The cation exchange capacity at a particle size of $10{\mu}m$ was 114.63 meq/100g probably due to the porous structure. The potential value of porous feldspar porphyry as a resource is sufficient based on the results of the experiment.

• KSBB Journal
• /
• v.6 no.2
• /
• pp.167-174
• /
• 1991

Enzymatic cellulose hydrolysis depends on the several factors such as the structural features (CrI, particle size and surface area, etc.), the nature of cellulase enzyme system, the inhibitory effects of products, and enzyme deactivation. At the presence of products on the initial hydro- lysis rate of cellulose, cellobiose has more severe inhibitory effect than glucose. Othewise, the inhibition effect of products for adsorbed enzyme is related to the glucose and cellobiose conentration hyperbolically. Enzyme deactivation of FPA and ${\beta}-glucosidase$ were expressed by exponential decay profile.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2010.02a
• /
• pp.93-93
• /
• 2010

Semiconductor nanocrystal quantum dots (NQDs) have recently attracted considerable interest for use in photovoltaics. Band gaps of NQDs can be tuned over a considerable range by varying the particle size thereby allowing enhance absorption of solar spectrum. NQDs, synthesized using colloidal routes, are solution processable and promise for a large-area fabrication. Recent advancements in multiple-exciton generation in NQD solutions have afforded possible efficiency improvements. Various architectures have attempted to utilize the NQDs in photovoltaics, such as NQD-sensitized solar cell, NQD-bulk-heterojuction solar cell and etc. Here we have fabricated CdSe NQDs with the band gap of 1.8 eV to 2.1 eV on thin-layers of p-type organic crystallites (1.61 eV) to realize a donor-acceptor type heterojuction solar cell. Simple structure as it was, we could control the interface of electrode-p-layer, and n-p-layer and monitor the following efficiency changes. Specifically, surface molecules adsorbed on the NQDs were critical to enhance the carrier transfer among the n-layer where we could verify by measuring the photo-response from the NQD layers only. Further modifying the annealing temperature after the deposition of NQDs on p-layers allowed higher conversion efficiencies in the device.

• Journal of Korean Society of Water and Wastewater
• /
• v.19 no.2
• /
• pp.135-143
• /
• 2005

It was evaluated that the effect of turbidity removal by Pore Controllable Fiber Filter(PCF) installed in NS(Naksang) small water treatmant plant(system) using under flow water as raw water in the study. The results of the study are as the followings. Firstly, the removal efficiency of turbidity by PCF without coagulation(in operation mode not using coagulants) was mostly below 20 percent. On the other hand, when operation using proper coagulants, that of turbidity was mostly over 80 percent. Secondly, slow sand filtration after PCF, total turbidity removal efficiency of final treated water was 84.3 percent, and the contribution by PCF was 57.1 percent and that of slow sand filtration was 27.7 percent. Therefore the introduction of PCF as pre-treatment process would be helpful to reduce the loading of high turbidity of slow sand filtration. Thirdly, the results of particle counter measurements showed that when operated PCF with coagulants, fine flocs captured or adsorbed at the pore of PCF were flow out into the effluents from 120 minutes after backwashing because of the increase of headloss of PCF. Therefore the decision of backwashing time should made consideration into the outflow of fine flocs from PCF. Fourth, coagulant dosages on PCF at the same turbidity was largely variable because of the effect of the raw water characteristics and the turbidity increase velocity at rainy days, therefore flexible coagulant dosages should be considered rather than fixed coagulant dosage by the influent jar-test result.

• Fire Science and Engineering
• /
• v.26 no.4
• /
• pp.42-47
• /
• 2012

In the study, fire extinguishing concentration of $K_2CO_3$-Zeolite composite was measured. Zeolite composite is a porous adsorbent which has small particle size, low density and anti-catalytic effect. Scanning Electron Microscopy, X-Ray diffraction and thermal analysis were also conducted to investigate the structural properties of composite. The result showed that despite of weight ratio, the extinguishing concentration of the composite was lower than pure $K_2CO_3$. The extinguishing concentration of $K_2CO_3$-Zeolite composite which has weight ratio of 7 : 3 was 5.72 times lower than that of pure $K_2CO_3$ and 1.1 times lower than that of ABC powder. The SEM and XRD patterns showed that $K_2CO_3$ was adsorbed on the Zeolite properly, and through the thermal analysis, it was founded that the composite is more effective extinguishing agent than pure $K_2CO_3$.

• Polymer(Korea)
• /
• v.33 no.2
• /
• pp.124-130
• /
• 2009

In presence of a polymer, the crystallization of low MW organic materials can be stopped at an intermediary step, where mesocrystals can be identified. A mesocrystal is defined as a superstructure of nanoparticles having polymer-adsorbed crystal faces on the scale of several hundred nanometers to micrometers. This study examined the effects of water soluble polymers and relevant parameters on the formation of guanosine-5'-monophosphate mesocrystals. It was observed in OM and SEM that GMP obtained in a polymer solution had a unique particle morphology different from the typical one of GMP. XRD analysis indicated that the polymer-directed crystallized GMP had a different polymorph of GMP. This result shows that the crystal structure of GMP can be changed by polymers. It was observed in TGA analysis that the polymer-directed crystallized GMP had a different water content, indicating a different type of hydrate.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.30 no.1C
• /
• pp.7-15
• /
• 2010

In case that the seepage of contaminants into the subsurface has been generated from the waste impoundment by demage of geomembrane liner, it is necessary to repair the leaks of geomembrane liner for minimizing the environmental contamination by electrophoresis method. However, when electrophoresis method is applied to leachate electrolyte system, the phenomenon of clay particles flocculation would be accelerated by the interaction between clay particles and specific chemicals in leachate. In addition, the gravitational settling behaviour would be induced superior to the electrophoretic migration behaviour. Eventually, the limitations of field applicability for using the electrophoresis method are appeared. Therefore, 1-D enhanced electrophoresis method is conducted to prevent the clay flocculation and accelerate the migration of clay particles separately. After the 1-D enhanced electrophoresis experiment, we can get the results that the deflocculation effect of clay particles is increased by electrical repulsion of polymer, which adsorbed in clay particle edge, in case of using PAA dispersing agent.