This study showed that the optimized cleaning process using non-aqueous cleaning solvents is adaptable in the industrial field for existing 1.1.1-TCE cleaning solvents which is an ozone depleting sustance. Alternative cleaning solvent system substituted for existing cleaning solvent against non-aqueous pollutants(cutting & flux oil), was evaluated for the cleaning efficiency using gravimetric analysis method and surface change of sample by Image analyzer. The results showed that alternative solvents and process had excellent cleaning efficiency.

The field of printing use to pressurization ink using screen gassamer that is called screen printing. Existing cleaning solvent using screen printing are the organic solvents including aromatic compounds carried with poisonous and stench. Besides, cleaning method of current screen printing are for the most part mixed cleaning method of dipping and polish. Using 1,1,1-TCE, CFC-113 alternative system cleaning solvent be substituted for existing cleaning solvent against screen printing ink measured the cleaning efficiency according to gravimetric analysis method and property change of gassamer according to Image Analyzer. Also, Cleaning process system carry with excellent cleaning efficiency studied which was proposed new cleaning process including ultrasonic and vibration cleaning process be substituted for existing mixed cleaning method of dipping and polish.

Titania-supported chromium oxides with different loadings have been embarked in catalytic oxidation of trichloroethylene (TCE) to inquire association of the formation of crystalline Cr2O3 with catalytic performances. A better activity in the oxidative TCE decomposition at chosen temperatures was represented when chromium oxides (CrOx) had been dispersed on pure anatase-type TiO2 (DT51D) rather than on phase-mixed and sulfur-contained ones such as P25 and DT51. The extent of TCE oxidation at temperatures below 350℃ was a strong function of CrOx content in CrOx/DT51D TiO2, and a noticeable point was that the catalyst has two optimal CrOx loadings in which the lowest T50 and T90 values were measured for the TCE oxidation. This behavior in the activity with respect to CrOx amounts could be associated with the formation of crystalline Cr2O3 on the support surface, that is less active for the oxidation reaction, and an easier mobility of the surface oxygen existing in noncrystalline CrOx species with higher oxidation states, such as Cr2O8 and CrO3.

This study examined the treatment characteristics of hard-to-degrade pollutants such as TCE which are found in organic solvent and cleaning wastewater by nZVI that have excellent oxidation and reduction characteristics. In addition, this study tried to find out the degradation characteristics of TCE by Fenton-like process, in which H2O2 is dosed additionally. In this study, different ratios of nZVI and H2O2, such as 1.0 mM : 0.5 mM, 1.0 mM : 1.0 mM, and 1.0 mM : 2.0 mM were used. When 1.0 mM of nZVI was dosed with 1.0 mM of H2O2, the removal efficiency of TOC was the highest and the first order rate constant was also the highest. When 1mM of nZVI was dosed with 0.5 mM of H2O2, the first order rate constant and removal efficiency were the lowest. The size of first order rate constant and removal efficiency was in the order of nZVI 1.0 mM : H2O2 1.0 mM ＞ nZVI 1.0 mM : H2O2 2.0 mM ＞ nZVI 1.0 mM : H2O2 0.5 mM ＞ H2O2 1.0 mM ＞ nZVI 1.0 mM. It is estimated that when 1.0 mM of nZVI is dosed with 1.0 mM of H2O2, Fe2+ ion generated by nZVI and H2O2 react in the stoichiometric molar ratio of 1:1, thus the first order rate constant and removal efficiency are the highest. And when 1.0 mM of nZVI is dosed with 2.0 mM of H2O2, excessive H2O2 work as a scavenger of OH radicals and excessive H2O2 reduce Fe3+ into Fe2+. As for the removal efficiency of TOC in TCE by simultaneous dose and sequential dose of nZVI and H2O2, sequential dose showed higher first order reaction rate and removal efficiency than simultaneous dose. It is estimated that when nZVI is dosed 30 minutes in advance, pre-treatment occurs and nanoscale Fe0 is oxidized to Fe2+ and TCE is pre-reduced and becomes easier to degrade. When H2O2 is dosed at this time, OH radicals are generated and degrade TCE actively.

Cobalt titanates (CoTiOx), such as CoTiO3 and Co2TiO4, have been synthesized via a solid-state reaction and characterized using X-ray diffraction (XRD) and X-ray photoelectron spectroscopic (XPS) measurement techniques, prior to being used for continuous wet trichloroethylene (TCE) oxidation at 36℃, to support our earlier chemical structure model for Co species in 5 wt% CoOx/TiO2 (fresh) and (spent) catalysts. Each XRD pattern for the synthesized CoTiO3 and Co2TiO4 was very close to those obtained from the respective standard XRD data files. The two CoTiOx samples gave Co 2p XPS spectra consisting of very strong main peaks for Co 2p3/2 and 2p1/2 with corresponding satellite structures at higher binding energies. The Co 2p3/2 main structure appeared at 781.3 eV for the CoTiO3, and it was indicated at 781.1 eV with the Co2TiO4. Not only could these binding energy values be very similar to that exhibited for the 5 wt% CoOx/TiO2 (fresh), but the spin-orbit splitting (ΔE) had also no noticeable difference between the cobalt titanates and a sample of the fresh catalyst. Neither of all the CoTiOx samples were active for the wet TCE oxidation, as expected, but a sample of pure Co3O4 had a good activity for this reaction. The earlier proposed model for the surface CoOx species existing with the fresh and spent catalysts is very consistent with the XPS characterization and activity measurements for the cobalt titanates.

Oxidative TCE decomposition over TiO2-supported single and complex metal oxide catalysts has been conducted using a continuous flow type fixed-bed reactor system. Different types of commercial TiO2 were used for obtaining the supported catalysts via an incipient wetness technique. Among a variety of titanias and metal oxides used, a DT51D TiO2 and CrOx would be the respective promising support and active ingredient for the oxidative TCE decomposition. The TiO2-based CrOx catalyst gave a significant dependence of the catalytic activity in TCE oxidation reaction on the metal loadings. The use of high CrOx contents for preparing CrOx/TiO2 catalysts might produce Cr2O3 crystallites on the surface of TiO2, thereby decreasing catalytic performance in the oxidative decomposition at low reaction temperatures. Supported CrOx-based bimetallic oxide systems offered a very useful approach to lower the CrOx amounts without any loss in their catalytic activity for the catalytic TCE oxidation and to minimize the formation of Cl-containing organic products in the course of the catalytic reaction.

Catalytic wet oxidation of trichloroethylene (TCE) in water has been conducted using TiO2-supported cobalt oxides at 36oC with a weight hourly space velocity of 7,500 h-1. 5% CoOx/TiO2, prepared by using an incipient wetness technique, might be the most promising catalyst for the wet oxidation although it exhibited a transient behavior in time on-stream activity. Not only could the bare support be inactive for the wet decomposition reaction, but no TCE removal also occurred by the process of adsorption on TiO2 surface. The catalytic activity was independent of all particle sizes used, thereby representing no mass transfer limitation in intraparticle diffusion. XPS spectra of both fresh and used Co surfaces gave different surface spectral features for each CoOx. Co 2p3/2 binding energy for Co species in the fresh catalyst appeared at 781.3 eV, which is very similar to the chemical states of CoTiOx such as Co2TiO4 and CoTiO3. The used catalyst exhibited a 780.3-eV main peak with a satellite structure at 795.8 eV. Based on XPS spectra of reference Co compound, the TCE-exposed Co surfaces could be assigned to be in the form of mainly Co3O4. XRD patterns for 5% CoOx/TiO2 catalyst indicated that the phase structure of Co species in the catalyst even before reaction is quite comparable to the diffraction lines of external Co3O4 standard. A model structure of CoOx present predominantly on titania surfaces would be Co3O4, encapsulated in thin-film CoTiOx species consisting of Co2TiO4 and CoTiO3, which may be active for the decomposition of TCE in a flow of water.

A new method based on solid phase microextraction(SPME), coupled with GC/FID, has been developed for the determination of PCE and TCE in water samples. The experimental parameters affecting the SPME process (i.e, kinds of fibers, extraction time, desorption time, extraction temperature, volume ratio of sample to headspace, salt addition, and magnetic stirring) were optimized. The coefficients of determination (R2) for PCE and TCE were 0.9951 and 0.9831, respectively when analytes concentration ranges from 10 to 300㎍/L. The relative standard deviations were 3.4 and 2.1% for concentration of 10㎍/L(n=5), respectively. The detection limits of PCE and TCE were 0.5 and 1.3㎍/L, respectively.