• Journal of Powder Materials
• /
• v.15 no.2
• /
• pp.125-135
• /
• 2008

[ $TiO_2$ ] nanotubes for photocatalytic application have been synthesized by hydrothermal method. $TiO_2$ nanotubes are formed by washing process after reaction in alkalic solution. Nanotubes with different morphology have been fabricated by changing NaOH concentration, temperature and time. $TiO_2$ nanoparticles were treated inside NaOH aqueous solution in a Teflon vessel at $110^{\circ}C$ for 20 h, after which they were washed with HCl aqueous solution and deionized water. Nanotube with the most perfect morphology was formed from 0.1 N HCl washing treatment. $TiO_2$ nanotube was also obtained when the precursor was washed with other washing solutions such as $NH_4OH$, NaCl, $K_2SO_4$, and $Na_2SO_3$. Therefore, it was suggested that $Na^+$ ion combined inside the precursor compound slowly comes out from the structure, leaving nanosheet morphology of $TiO_2$ compounds, which in turn become the nanotube in the presence of hydroxyl ion. To stabilize the sheet morphology, the different type of washing treatment solution might be considered such as amine class compounds.

• Advances in environmental research
• /
• v.9 no.1
• /
• pp.65-84
• /
• 2020

The potential use of Sargassum boveanum algae for the removal of uranium from aqueous solution has been studied by varying three independent parameters (pH, initial uranium ion concentration, S. boveanum dosage) using a central composite design (CCD) under response surface methodology (RSM). Batch mode experiments were performed in 20 experimental runs to determine the maximum metal adsorption capacity. In CCD design, the quantitative relationship between different levels of these parameters and heavy metal uptake (q) were used to work out the optimized levels of these parameters. The analysis of variance (ANOVA) of the proposed quadratic model revealed that this model was highly significant (R² = 0.9940). The best set required 2.81 as initial pH(on the base of design of experiments method), 1.01 g/L S. boveanum and 418.92 mg/L uranium ion concentration within 180 min of contact time to show an optimum uranium uptake of 255 mg/g biomass. The biosorption process was also evaluated by Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherm models represented that the experimental data fitted to the Langmuir isotherm model of a suitable degree and showed the maximum uptake capacity of 500 mg/g. FTIR and scanning electron microscopy were used to characterize the biosorbent and implied that the functional groups (carboxyl, sulfate, carbonyl and amine) were responsible for the biosorption of uranium from aqueous solution. In conclusion, the present study showed that S. boveanum could be a promising biosorbent for the removal of uranium pollutants from aqueous solutions.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.35 no.5
• /
• pp.583-587
• /
• 2006

Aqueous solutions of sugar alone or in the presence of lysine were gamma irradiated at 0, 5, 10, 20 and 30 kGy at room temperature. Absorbances at 284 nm as an indicator of intermediate stage of non -enzymatic browning reaction increased with irradiation dose in both the solution of sugar or lysine alone and sugar-lysine mixed solution. Absorbances at 420 nm as indicator of browning increased in the irradiated sugar-lysine mixed solutions although no browning was observed in the irradiated solution of sugar or lysine alone. The degree of browning of the irradiated sugar-lysine mixed solution increased with irradiation dose and was dependent on the type of sugar. For sugar-lysine mixed solution irradiated at 30 kGy, the browning had the following order of intensity: sucrose>fructose>arabinose>xylose>glucose. However, the sugar loss of irradiated sugar lysine mixed solution had a following order of intensity: glucose>fructose>sucrose>xylose>arabinose. The reducing power of the non-reducing sugar, sucrose, was produced by gamma irradiation. The present results indicated that gamma irradiation leads to a non-enzymatic browning reaction (carbonyl-amine reaction) in an aqueous system.

• Membrane Journal
• /
• v.22 no.6
• /
• pp.481-488
• /
• 2012

The anionic exchange polymer, poly(vinyl amine)(PVAm), was coated onto polyamide (PA) reverse osmosis (RO) membranes by using 'salting-out' method. The effects of the fouling phenomena for these PVAm coated membranes were investigated using the model foulants, bovine serum albumin (BSA), humic acid (HA), and sodium alginate (SA). The surface coating and the fouling phenomena were observed by the scanning electron microscopy. And the flux was measured for each 100 ppm of above foulant aqueous solution at the operating pressure, 2, 4, 8 bar. The PVAm-coated PA membranes showed somewhat fouling improvements and the fouling reduction was shown in the order of HA > SA > BSA, particularly HA case was distinct.

• Archives of Pharmacal Research
• /
• v.23 no.4
• /
• pp.367-373
• /
• 2000

Cholic acid, conjugated with amine-terminated poly(W-isopropylacrylamide) (abbreviated as CA/ATPNIPAAm), was synthesized by a N, N'-dicyclohexyl carbodiimide (DCC)-mediated coupling reaction. Self-assembled CA/ATPNIPAAm micelles were prepared by a diafiltration method in aqueous media. The CA/ATPNIPAAm micelles exhibited a lower critical solution temperature (LCST) at $31.5^{\circ}C$. Micelle sizes measured by photon correlation spectroscopy (PCS) were approximately 31.6 $\times$$\times$ 5.8 nm. The CA/ATPNIPAAm micelles were spherical and their thermal size transition was observed by transmission electron microscope (TEM). A fluorescence probe technique was used for determining the micelle formation behavior of CA/ATPNIPAAm in aqueous solutions using Pyrene as a hydrophobic Probe. The critical micelle concentration (CMC) was evaluated as $8.9{\times}0^{-2}$ g/L. A drug release study was performed using indomethacin (IN) as a hydrophobic model drug. The release kinetics of IN from the CA/ATPNIPAAm micelles revealed a thermo-sensitivity by the unique character of poly(N-isopropylacrylamide) i.e. the release rate was higher at $25^{\circ}C$ than at $37^{\circ}C$.

• Macromolecular Research
• /
• v.13 no.3
• /
• pp.257-264
• /
• 2005

Polyurethanes containing z-Iysine segments in the main chain (PULL) were synthesized from 4,4'-diphe-nylmethyl diisocyanate, poly(tetramethylene glycol), and z-Iysine oligomer as a chain extender. The PULL film was treated first with a $10\%$ HBr-acetic acid solution and subsequently with a saturated sodium bicarbonate aqueous solution to produce a primary amine group on the surface (PULL-N). Lactobionic acid (LA)-immobilized PULL (PULL-L) was prepared by the coupling reaction of the PULL surface amine groups and the LA carboxylic acid groups. The surface-modified PULLs were then characterized by attenuated total reflection-Fourier transform infra-red spectroscopy, electron spectroscopy for chemical analysis, atomic force microscopy, and contact angle goniometry. In the hepatocytes adhesion experiment, the cells poorly adhered to the PULL surface, although they adhered moderately well to the PULL-N surface. On the other hand, the cells adhered well to the PULL-L surface, suggesting the good affinity of the surface $\beta$-galactose moieties for hepatocytes. When hepatocytes were cultured in the presence of epidermal growth factor for 48 h, the cells rapidly aggregated on the PULL-L surface, whereas they aggregated only slowly on the other surfaces. The PULL prepared in this study has the potential to be used as a coating material for the enhancement of hepatocyte adhesion.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.02a
• /
• pp.611-611
• /
• 2013

In this study, iron oxide nanoclusters layer (Nc) was prepared onto functionalized silicon substrate by wet method. The amine-terminated SAM fabricated on silicon substrate (APTMS/Si) was carried out by UV-treatment and immersed into the FeCl3/HCl aqueous solution. Then, Nc were immobilized onto oxidized SAM silicon substrate (SAMs/Si) through electrostatic interaction between cationic Nc and anionic SAMs/Si. This catalytic layer (Nc/SAMs/Si) was used to grow carbon nanotubes (CNTs). The characterization results clearly show that the well-graphitized CNTs were synthesized by using functionalized silicon substrate as a template having appropriate density of catalyst. These consequences show that SAM containing template is important to achieve the effective layer of catalyst to synthesize CNTs.

• Bulletin of the Korean Chemical Society
• /
• v.24 no.12
• /
• pp.1767-1770
• /
• 2003

A simple, rapid and sensitive spectrophotometric method is herewith proposed for the determination of copper(II) by using diamine-dioxime ligand, meso-3,6,6,9-tetramethyl-4,8-diazaundecane-2,10-dione dioxime or meso-HexaMethyl Propylene Amine Oxime (meso-HMPAO). This method is based on the formation of a stable 1 : 1 red-pink complex between copper(II) and meso-HMPAO in aqueous solution. Absorption measurements were carried at 497 nm, with a molar absorptivity value of 338 L $mol^{-1}\;cm^{-1}$. Beer's law was obeyed over the concentration range of 0.5-370 ${\mu}$g $mL^{-1}$ with a Sandell's sensitivity value of 0.18 ${\mu}$g $cm^{-2}$. The proposed method has been successfully applied for determination of copper(II) in foodstuffs and pharmaceutical samples. The results obtained from this method are comparable with those obtained AAS.

• Textile Coloration and Finishing
• /
• v.9 no.6
• /
• pp.79-86
• /
• 1997

The microcapsule for thermochromism is based on the polymerization reaction between epoxy resin and amine curing agent. The preparation process of microcapsule is based on dissolving or dispersing a hydrophobic core materials[one-dye-black(OBD), bis-phenol A(BPA), cetyl alcohol] in an aqueous solution of gelatin, epoxy resin and isophorondiamine(IPDA) ; the gelatin and IPDA used as a dispersion stabilizer and an hardening agent, respectively. The structures of epoxy resin and microcapsule materials have been analyzed by FT-IR and UV/Vis spectra. The mean diameter and size distribution of microcapsule are 1.46~1.75${\mu}{\textrm}{m}$ and 1.42, respectively. The DSC thermograms of microcapsules indicated 2 kinds of endothermic peaks at 47 and 322$^{\circ}C$. This is possibly corresponding to the melting peak of core material and wall meterial. These microcapsules are applied to the fabric by printing. Complex finished fabric showed a good wear resistance on rubbing test and the print pattern to the cotton fabric showed a reversible thermochromism ; ${\mu}_{max}$ are 580 nm below 4$0^{\circ}C$ and 276.5nm above 4$0^{\circ}C$ in ethanol/water(2/8), respectively.

• Polymer(Korea)
• /
• v.39 no.1
• /
• pp.165-168
• /
• 2015

Thermoresponsive polymers were successfully synthesized by a combination of atom transfer radical polymerization (ATRP) and Cu(I)-catalyzed 1,3-dipolar cycloaddition of azide and alkynes (click chemistry). Poly(2-hydroxyethyl methacrylate) (PHEMA) was synthesized by ATRP, followed by introduction of alkyne groups using pentynoic acid, leading to HEMA-alkyne. Homopolymers having secondary amine groups, tertiary amines with hydroxyethyl and hydroxypropyl groups were synthesized by adding 2-azido-N-ethyl-ethanamine, 2-[(2-azidoethyl)amino]ethanol, and 2-[(2-azidoethyl)amino]propanol, respectively, to the PHEMA-alkyne backbone using click chemistry. Molecular weight (MW), molecular weight distribution (MWD), and click reaction efficiency were determined by gel permeation chromatography (GPC) and $^1H$ NMR spectroscopy. The transmission spectra of the 1.0 wt% aqueous solutions of the resulting polymers at 650 nm were measured as a function of temperature. Results showed that the lower critical solution temperature (LCST) could be easily controlled by the length of the hydroxyalkyl groups.