Geug-Tae Kim

Growth and characterization of chloronitroaniline crystals for optical parametric oscillators: I. XPS study of Mo-based compounds

Abstract The surface electronic structures and compositions of Mo-based compounds (oxides and nitrides) have been elucidated using X-ray photoelectron spectroscopy (XPS). The Mo nitride samples were synthesized using the temperature-programmed nitridation of a low surface area MoO3 with NH3. The Mo oxides were also used to compare XPS results. No significant change was observed in the surface electronic structure of core levels of Mo 3d, Mo 3p, N 1s, and O 1s for Mo nitrides after the hydrogen reduction. A species with a Mo 3d5/2 binding energy of 228.4±0.2 eV from Mo nitrides was newly observed and was calculated to be Mo1.3+. This value indicates that the absolute magnitude of charge transfer from Mo 4d states to N 2p states is 1.3 electrons per molybdenum in Mo nitrides. The binding energies of Mo 3d5/2 were shifted to lower ones (232.5→230.0→228.4 eV) as the oxides were transformed to nitride during nitridation (Mo6+→Mo4+→Moδ+). There are two different regions (nitride and oxide regions) present on the Mo nitride surface as shown from the deconvoluted Mo 3d peaks. For the Mo nitrides prepared in this study the nitride fraction was observed to be a majority on the surface.

Adsorption of Pb2+ and Pd2+ on polyethylene membrane with amino group modified by radiation-induced graft copolymerization

Six chelating hollow fiber membranes were prepared by radiation-induced grafting of glycidyl methacrylate onto a polyethylene hollow fiber membrane and its subsequent amination. The adsorption characteristics of Pb2+ and Pd2+ for the chelating hollow fiber membranes were presented when the solution of Pb2+ and Pd2+ permeates across the chelating membrane, respectively. The degree of grafting for glycidyl methacrylate increases with increasing monomer concentration, reaction temperature, and preirradiation dose. The adsorption of Pd2+ by chelating hollow fiber membranes modified with five kinds of amines was in the following order: diethylene triamine > hexamethyl diamine > ethylene diamine > dimethyl amine > trimethyl amine. The chelating hollow fiber membrane modified with iminodiacetic acid adsorbed Pb2+ ions much more than Pd2+.

Thermal and Catalytic Degradation of Waste High-density Polyethylene (HDPE) Using Spent FCC Catalyst

Thermal and catalytic degradation using spent fluid catalytic cracking (FCC) catalyst of waste high-density polyethylene (HDPE) at 430 °C into fuel oil were carried out with a stirred semi-batch operation. The product yield and the recovery amount, molecular weight distribution and paraffin, olefin, naphthene and aromatic (PONA) distribution of liquid product by catalytic degradation using spent FCC catalyst were compared with those by thermal degradation. The catalytic degradation had lower degradation temperature, faster liquid product rate and more olefin products as well as shorter molecular weight distributions of gasoline range in the liquid product than thermal degradation. These results confirmed that the catalytic degradation using spent FCC catalyst could be a better alternative method to solve a major environmental problem of waste plastics.