Chang-Sik Ju

Synthesis of TiO2/SiO2 nanoparticles in a water-in-carbon-dioxide microemulsion and their photocatalytic activity

TiO2 and TiO2/SiO2 nanoparticles were prepared by controlled hydrolysis of titanium tetraisopropoxide and tetraethylorhtosilicate in water-in-carbon-dioxide microemulsion using ammonium carboxylate perfluoro-polyether (PFPE-NH4) as a surfactant. These particles were characterized by HRTEM, XRD, FT-IR, TGA and DTA. The particles calcined at 500°C were identified as a nanocrystalline anatase phase, regardless of the titanium tetraisopropoxide/teraethylorthosilicate (TTIP/TEOS) molar ratio. The crystallite size decreased with an increase of the silica content. From FT-IR analysis, the band for Ti-O-Si vibration was observed and the band intensity for Si-O-Si vibration increased with an increase of the silica content. The micrographs of HRTEM showed that the TiO2/SiO2 nanoparticles had a spherical morphology with a narrow size distribution and the lattice fringe was 0.35 nm, which corresponds to the lattice spacing of (101) plane in the anatase phase. In addition, TiO2/SiO2 particles showed higher photocatalytic activity than pure TiO2 and the TiO2/SiO2 (80:20) particles showed the highest activity on the photocatalytic decomposition of p-nitrophenol.

Extraction of Strontium Ion from Sea Water by Contained Liquid Membrane Permeator

To develop a liquid membrane permeator that extracts strontium ion from sea water effectively and continuously, we investigated the extraction of strontium ion from artificial and natural sea water in a contained liquid membrane permeator. The permeator consists of a liquid membrane and two cells for aqueous solutions. The liquid membrane containing D2EHPA(di-2-ethylhexyl-phosphoric acid) and DCH18C6(dicyclohexano-18-crown-6) is trapped between two hydrophobic microporous polyethylene films and separates sea water and the 0.2 M H2SO4 aqueous stripping solution. The effects of various operating parameters on the extraction of strontium ion were experimentally examined. The extractant of DCH18C6 -D2EHPA mixture in kerosene had a synergistic effect on the extraction of strontium ion. The permeator extracted strontium ion from sea water effectively and continuously with long membrane lifetime.

The effect of dominant ions on solvent extraction of lithium ion from aqueous solution

Solvent extraction of lithium ion using kerosene as solvent is proposed. The extraction of lithium ion using various mixed extractants of β-diketone and neutral ligand in kerosene was performed to find the optimum extractant combination. Considering the extraction efficiency, the optimum extractant combination was 0.02 M TTA and 0.04M TOPO. For the development of lithium extraction from seawater, the effects of dominant ions in seawater were examined in various extraction conditions. The extraction efficiencies generally decreased with the concentration of dominant metallic ions and increased with pH of the aqueous solutions, but Cl− ion showed only minor effect on the efficiency, even up to its concentration in seawater. Except for Mg2+ ion, more than 70% of lithium ions could be extracted at pH 10.6 from aqueous solutions with a dominant ion at its concentration in seawater.

Preparation of nanosized TiO2 particles via ultrasonic irradiation and their photocatalytic activity on the decomposition of 4-nitrophenol

TiO2 nanoparticles were prepared by hydrolysis of TTIP (titanium tetraisopropoxide) using an ultrasonication technique coupled with a sol-gel method. The physical properties of nanosized TiO2 were investigated. The photocatalytic degradation of 4-nitrophenol was studied by using a batch reactor in the presence of UV light. The crystallite size of the anatase phase is increased with an increase of REtOH ratio (EtOH/H2O molar ratio). The particles’ crystallite size prepared with and without ultrasonic irradiation is marginally different. Those particles prepared with ultrasonic irradiation show a higher activity on the photocatalytic decomposition of 4-nitrophenol compared to those prepared without ultrasonic irradiation. The photocatalytic activity decreases with an increase of REtOH ratio. In addition, the photocatalytic activity shows the highest value on the titania particle calcined at 500 ‡C.

Preparation of indium tin oxide powder from low-grade metallic indium and tin

Preparation of indium-tin oxide(ITO) powder by oxalic acid from metallic indium and tin was investigated. The intermediate(indium-tin oxalate salt) was formerly prepared at various conditions, and thermal decomposition was followed to obtain ITO powder for ITO target. Optimum conditions for preparation of the intermediate were oxalic acid concentration 2.0 M, pH 8.0, reaction temperature 80 °C and reaction time 6 hours. The purity of the intermediate could be increased by recrystallization up to 99.99% (4 N). The phase transition temperature of the intermediate to ITO powder was analyzed by TGA. The purity, crystal structure and particle shape of ITO powder were examined by ICP-OES, XRD and TEM, respectively. ITO powder obtained was spherical, whose size was 20–50 nm.

Preparation of indium oxide from waste indium tin oxide targets by oxalic acid

Indium oxide manufacturing process from waste indium tin oxide (ITO) targets by oxalic acid was experimentally studied. The process was composed of precipitation of intermediate (indium-oxalate salt), re-crystallization and its thermal decomposition. The waste ITO targets were generated from vacuum sputtering process. The effects of operating parameters, such as solid dosage, oxalic acid concentration, reaction temperature and time, on the precipitation and re-crystallization of indium-oxalate salt were examined. Thermal decomposition to indium oxide was also investigated. The optimum reaction conditions to indium-oxalate salt were oxalic acid concentration 1.5 M, solid dosage 50 g/L, reaction temperature 80 °C and reaction time 8 hours. The purity of indium-oxalate salt prepared by precipitation and re-crystallization was 99.99% (4 N), and the salts were thermally decomposed to indium oxide at over 600 oC. The purity of the final product, indium oxide, was dependent on that of the intermediate, indium oxalate salt.

Synthesis of Nonionic Sorbitan Monostearate Using High Purity 1,4-sorbitan

Nonionic sorbitan monostearate have been successfully prepared by esterification using 1,4-sorbitan and stearic acid. 1,4-sorbitan were prepared using D-sorbitol and acid catalyst at solvent-free conditions. The synthesized surfactants were characterized by NMR and FT-IR. We also investigated the effect of temperature, pressure and catalyst on the synthesis of nonionic sorbitan monostearate. The yields of 1,4-sorbitan were 90% at under 160 mmHg vacuum, and the yields of nonionic sorbitan monostearate were 92% at under 60 mmHg vacuum.

Synthesis of Highly Pure 1,4-Sorbitan for Preparation of Anti-Fogging Agent

【In order to develope an efficient way for the synthesis of highly pure 1,4-sorbitan solution from sorbitol, some experimental studies were performed. The reaction showed first order reaction with activation energy of 118.3 KJ/mol. Color of the product solutions changed to brown with reaction temperature and reaction time. The equilibrium contents of 1,4-sorbitan increased with decrease in reaction pressure, but the content of major impurity, sorbide, showed maximum about 550 torr vacuum with

Development of Environmentally Friendly Aqueous Cleanser by Emulsification of D-Limonene

H_3PO_4

Synthesis of TiO2 particles by reverse microemulsion method using nonionic surfactants with different hydrophilic and hydrophobic group and their photocatalytic activity

catalyst. The reasonable catalyst configuration was 0.26 wt% PTSA and 1 wt%