• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.197-197
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• 2011

In this study, in contrast with cases in which Scanning Tunneling Microscopy (STM) tip-induced reactions were instigated by the tunneling electrons, the local electric field, or the mechanical force between a tip and a surface, we found that the tungsten oxide (WO3) covered tungsten (W) tip of a STM acted as a chemical catalyst for the S-H dissociative adsorption of phenylthiol and 1-octanethiol onto a Ge(100) surface. By varying the distance between the tip and the surface, the degree of the tip-catalyzed adsorption could be controlled. We have found that the thiol head-group is the critical functional group for this catalysis and the catalytic material is the WO3 layer of the tip. After removing the WO3 layer by field emission treatment, the catalytic activity of the tip has been lost. 3-mercapto isobutyric acid is a chiral bi-functional molecule which has two functional groups, carboxylic acid group and thiol group, at each end. 3-Mercapto Isobutyric Acid adsorbs at Ge(100) surface only through carboxylic acid group at room temperature and this adsorption was enhanced by the tunneling electrons between a STM tip and the surface. Using this enhancement, it is possible to make thiol group-terminated surface where we desire. On the other hand, surprisingly, the WO3 covered W tip of STM was found to act as a chemical catalyst to catalyze the adsorption of 3-mercapto isobutyric acid through thiol group at Ge(100) surface. Using this catalysis, it is possible to make carboxylic acid group-terminated surface where we want. This functional group-selective adsorption of bi-functional molecule using the catalysis may be used in positive lithographic methods to produce semiconductor substrate which is terminated by desired functional groups.

• Applied Chemistry for Engineering
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• v.24 no.1
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• pp.24-30
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• 2013

The adsorption characteristics of cationic starches and starch-oligomers were investigated using the quartz crystal microbalance with dissipation monitoring (QCM-D). The adsorbed amount of modified starches was higher than that of cationic surfactants such as $C_{12{\sim}16}$ trimethylammonium bromide. Cationic starches did not show the tendency depending on the degree of cationic substitution and molecular weight. On the other hand, the softness of the adsorption layer increased with the molecular weight of cationic starches in a viscoelasticity terms. During the adsorption/desorption steps, the amount of adsorbed cationic surfactants was 4~9 times. On the other hand, the difference in the amount of adsorption of all the $C_1$ grafted cationic starches was just 0~50%. In addition, the rigidity of the adsorption layer of cationic surfactant in the desorption step decreased, while, that of cationic starches increased at the same condition.

• Polymer(Korea)
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• v.26 no.2
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• pp.160-167
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• 2002

We synthesized HPP-g-GMA copolymer using pre-irradiation method by E-beam and aminated HPP-g-GMA using amination reaction. Degree of grafting increased with increasing GMA monomer concentration and showed the maximum value of 130% at 1.46 M of GMA. The degree of amination increased with increasing the degree of grafting. When the degree of grafting was 100%, degree of amination showed the maximum value of 37.4%. The ion exchange capacity of aminated HPP-g-GMA was about 3.78 meq/g, and it showed remarkable adsorption ability of hollow fiber ion exchanger. Through the BET analysis, the surface area of aminated HPP-g-GMA was 54.83 $\m^2/g$ and the mean pore size was $26\AA$. These showed the decrease of surface area and the slight increase of the mean pore size. SEM results show that the thickness of fiber increased after the step of reaction and there pore blocking phenomena was not observed. The aminated HPP-g-GMA was synthesized successfully and found to be suitable for the adsorption and separation of anion.

• Journal of environmental and Sanitary engineering
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• v.14 no.3
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• pp.63-70
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• 1999

A study on the zeolite synthesized of bituminous coal fly ash from power plant has been carried out to reuse industrial waste. The synthesized zeolite was proved to be 4A type by means of the X-ray diffraction analysis and the degree of crystallinity was found to be higher than 90%. Then the synthesized zeolite was used as an adsorbent to remove the heavy metal ions in the CU, Pb, and Cd containing wastewater and water. Also, adsorption characteristics and kinetics of synthesized zeolite in the each metal ion solutions were studied. In each ion solutions, the adsorbed amounts of Pb, Cd, and Cu to the unit weight of synthesized zeolite were 141.6, 118.8, and 131.4mg/g respectively when each metal ion concentration was 500mg/L solution. The adsorption kinetics was fitted well to the Freundlich isotherms. The value of l/n for Pb, Cd, and Cu and 0.27, 0.50, and 0.66, respectively. Those results showed that the synthesized zeolite could be used as an adsorbent to remove single heavy metal ions in the wastewater and water. The heats of adsorption, H values of Pb, Cd, and Cu were 4.87, 14.95, and 18.23kacl/mol by the Henry-van't Hoff equation.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.42 no.2
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• pp.1-11
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• 2010

The possibility of applying birchwood xylan in papermaking process to improve dry strength of paper was investigated. Unmodified xylan barely adsorbed onto pulp fibers while cationically modified xylan adsorbed substantially. Adsorption of cationically modified xylan by quaternarization with 3-chloro-2-hydroxypropy trimethylammonium chloride improved dry strength of paper. Chemical structure and degree of substitution of the cationically modified xylan was determined by 400 MHz 13CNMR spectroscopy and elemental analyzer. The amount of adsorbed xylan on cellulose fibers was greater when the cationicity was moderate, and it was interpreted that the conformation of this cationic xylan adsorbed on fiber surface was more favorable for greater adsorption due to its greater loop formation tendency while highly cationic xylan tends to adsorbed in stretched conformation. The physical properties of handsheets increased as the amount of adsorbed cationic xylan increased. On the other hands, the optical properties decreased with xylan adsorption.

• Bulletin of the Korean Chemical Society
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• v.8 no.5
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• pp.398-403
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• 1987

A general theory of polymer adsorption at a semi-permeable oil-water interface of the biphasic solution is presented. The configurational factor of the solution in the presence of the semi-open boundary at the interface is evaluated by the quasicrystalline lattice model. The present theory gives the feature of the bulk concentration equilibria between oil-water subsystems and the surface excesses of ${\Gamma}^{\alpha}$ and ${\Gamma}^\{beta}$ of the polymer segments as a function of the degree of polymerization $\gamma$, the Flory-Huggins parameter in $\beta$-phase $x_{\rho}^{{\beta}_{\rho}}$, the differential adsorption energy parameter in $\beta$-phase $x_{\sigma}^{{\beta}_{\rho}}$, the differential interaction energy parameter ${\Delta}x_{\rho}$ and the bulk concentration of the polymer in ${\beta}-phase ${\varphi}_2^{{\beta(*)}_2}$. From our numerical results, the characteristics of ${\Gamma}^{\alpha}$ are shown to be significantly different from those of ${\Gamma}^{\beta}$ in the case of high polymers, and this would be the most apparent feature of the adsorption behavior of the polymer at a semi-permeable oil-water interface, which is sensitively dependent on ${\Delta}x_{\rho}$ and r.

• Polymer(Korea)
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• v.25 no.1
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• pp.49-55
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• 2001

The bi-functional ion exchangers, SAPP-g-(AN/St) were synthesized with mixed vinyl monomers(acrylonitrile and styrene) onto PP fabric by the pre-irradiation grafting with E-beam and its subsequent amidoximination and sulfonation. The degree of grafting of PP-g-(AN/St) was increased with decreasing acrylonitrile composition in the mixed monomers. The water uptake of copolymers increased with decreasing in the amidoxime ratio in the copolymers and increased by sulfonation, but decreased by amidoximation. The $UO_2^{2+}$ adsorption capacity of SPP-g-St, APP-g-AN, and SAPP-g-(AN/St) were 12.4, 34.0, and 38.0 mg/g, respectively and the optimum adsorption time is about 50 hrs. As a result of uranium adsorption, the synthesized ion exchanger, which we obtained have also good affinity toward the adsorption or chelating with $UO_2^{2+}$ ions.

• Environmental Engineering Research
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• v.25 no.4
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• pp.536-544
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• 2020

To address organic dye wastewater, economic and effective adsorbents are required. Here, magnetic biochar from alkali-activated rice straw (AMBC) was successfully synthesized using one-step magnetization and carbonization method. The alkaline activation caused the large specific surface area, high pore volume and abundant oxygen-containing groups of the AMBC, and the magnetization gave the AMBC a certain degree of electropositivity and fast equilibrium characteristics. These characteristics collectively contributed to a relative high adsorption capacity of 53.66 mg g^-1 for this adsorbent towards rhodamine B (RhB). In brief, RhB can spontaneously adsorb onto the heterogeneous surface of the AMBC and reach the equilibrium in 60 min. Although the initial pH, ionic strength and other substances of the solution affected the adsorption performance of the AMBC, it could be easily regenerated and reused with considerable adsorption content. Based on the results, H-bonds, π-π stacking and electrostatic interactions were speculated as the primary mechanisms for RhB adsorption onto the AMBC, which was also demonstrated by the FTIR analysis. With the advantageous features of low cost, easy separation, considerable adsorption capacity and favorable stability and reusability, the AMBC would be a potential adsorbent for removing organic dyes from wastewater.

• Journal of environmental and Sanitary engineering
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• v.10 no.2
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• pp.1-12
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• 1995

Under accelerated industrial developments environment pollution comes out to be very stirious. Especially the ions of heavy metal from wastewater, even if they are minimal, accumulated in ecology circle and do finally injury to human health. The general process for removal of heavy metals include coagulation and following sedimentation, ion -exchange and active carbon adsorption and sedimentation that applicate in popular, needs the expense of coagulant the additional treatment of sludge on the general process of coagulation and sedimentation. It is also a serious problem that the second pollution caused by coagulant. However chelating adsorption that uses natural chelating high- molecular compound has not pollution problem Among chelating high- molecules, the diminishing chitin that contained in crustaceans as crawfish and crab in our country with affluent water resources are easy to get. So it is advantageous to use this ubiquitous material for removing heavy metals because we could reuse natural resource. In this research, the author tested the effectiveness of the adsorption and removal of heavy metal ions by chitin and its derivatives. Chitin and cellulose became beads and used as flocculant, in this test. The results are as follows . First, bead showed higher removal ratio than powder in the comparative test on adsorbents such as chitin, chitosan and cellulose. Secondly, in the variety test by the kinds of adsorbent and time. chitosan bead and cellulose bead that showed the highest removal ratio. One hour need to remove the ions of heavy metal. Thirdly, the results of the adsorption degree test by pH revealed high removal ratio adsorption of chitin, cellulose and chitosan bead in alkalin condition but chitosan bead in acidic condition.

• Polymer(Korea)
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• v.27 no.1
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• pp.69-74
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• 2003

In this study, we have investigated the adsorption properties for nitrate ion in ground water using mixed resin type hybrid ion exchange (HIXF) and fiber type ion exchanger. Their swelling ratio (4.45 g/g) and ion exchange capacities (2.45 meq/g) were higer than the swelling ratio of IEC and IXF. Adsorption yield increased for nitrate $NO_3^-$ and sulfate $SO_4^{2-}$ ions were optimal at the concentration ratios of nitrate and sulfate below 1.0 and the adsorption yields were 100% and 20%, respectively. On the other hand it was shown that the degree of adsorpted for nitrate to pH 3, but it was little changed in the other pH range. We found that the selective adsorption capacity for nitrate was the optimal the mixing ratios of resin and fibrous ion exchanger of below 0.5.