• Environmental Engineering Research
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• v.10 no.2
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• pp.54-61
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• 2005

Liquid-phase catalytic degradation of waste high-density polyethylene (HDPE) over ZSM-5 (powder type (PW)) and ZSM-5+binder (granule type (GR)) has been investigated with a stirred semi-batch operation at 400°C. Two ZSM-5 catalysts with a different crystal size were synthesized and also each ZSM-5 (25%) Catalyst was mixed with a same binder (kaolin: silica sol: alumina = 55%:10%:10%). The performance of prepared catalysts that has different physicochemical properties was discussed with the cumulative amount distribution, molecular weight distribution and also paraffin, olefin, naphthene and aromatic (PONA) distribution in liquid product. These liquid product quality and distributions were changed depending on the physicochemical properties of the catalyst. Moreover, the characteristic of ZSM-5 in the catalyst was strongly influenced on the activity and PONA distribution in liquid product.

• New & Renewable Energy
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• v.5 no.4
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• pp.52-58
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• 2009

Upgrading of pyrolysis wax oil using HZSM-5 catalyst has been conducted in a continuous fixed bed reactor at $450^{\circ}C$, 1hour, LHSV 3.5/h. The catalytic degradation was studied with a function of catalyst amount and reaction temperature. The raw pyrolysis wax oil shows relatively high boiling point distribution ranging from around $300^{\circ}C$ to $550^{\circ}C$, which has considerably higher boiling point distribution than that of commercial diesel. The catalytic degradation using HZSM-5 catalyst shows the high conversion of pyrolysis wax oil to light hydrocarbons. The liquid product obtained shows high gasoline range fraction as around 90% fraction and considerably high aromatic fraction in liquid product. Here, the experimental variable such as catalyst amount and reaction temperature was influenced on the product distribution.

• Asian Journal of Atmospheric Environment
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• v.2 no.2
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• pp.75-80
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• 2008

A new-type apparatus decomposing volatile organic compounds (VOCs) using a combination system of an electrical exothermic SiC honeycomb and a catalytic filter was developed. This linear combination system is very useful to the catalytic decomposition of VOCs, because the gas involving VOCs is well heated in the SiC honeycomb and then flows into the catalytic filter. In the proposed apparatus, the outlet gas temperatures of SiC honeycomb maintained at ca. $300^{\circ}C$ after 5 min from the starting of applying electric current, and sufficient for the catalytic degradation of VOC components, i.e. toluene, isopropanol, methyl ethyl ketone and ethyl acetate. The average decomposition rate of total VOCs exhausted from a printing factory was 85% using pt catalyst at SV=19,000 in this system.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2005.11a
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• pp.554-555
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• 2005

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.286-291
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• 2001

As part of fundamental studies on the degradation of the organic compounds in industrial waste water, the photocatalytic degradation properties of the organic compound by means of the UV/TiO$_2$degradation process have been investigated. The test organic compound of acetic acid was chosen in this study. The testing of photo catalytic degradation were performed under various operation conditions such as TiO$_2$dosages, initial concentration of the organic, the aqueous pH's, etc. The effects of various parameters on the short time activity of the present acetic acid-UV/TiO$_2$system could be demonstrated from this investigation.

• Clean Technology
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• v.23 no.4
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• pp.408-412
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• 2017

Pigment red 53:1 is a dye used in various products as a component of the inks, suspected of being carcinogenic. Thus, the environmental and occupational issues related to it are important. The enzyme-based approach with reusability has advantages to consume less energy and generate less harsh side- products compared to the conventional strategies including separations, microbe, and electrochemical treatment. The degradation of Pigment red 53:1 by the lignin peroxidase immobilized on the surface of magnetic particles has been studied. The immobilization of the peroxidase was conducted on magnetic particle surface with the treatment of polyethyleneimine, glutaraldehyde, and the peroxidase, in sequence. The immobilization was confirmed using X-ray photon spectroscopy. The absorbance peak of the pigment was monitored at 495 nm of UV/Vis spectrum with respect to time to calculate the catalytic activities of the pigment for the immobilized lignin peroxidase. For the comparison, the absorbance of the lignin peroxidase free in solution was also monitored. The catalytic rate constant values for the free lignin peroxidases and the immobilized those were 0.51 and $0.34min^{-1}$, respectively. The reusable activity for the immobilized lignin peroxidase was kept to 92% after 10 cycles. The stabilities for heat and storage were also investigated for both cases.

• Korean Journal of Metals and Materials
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• v.49 no.8
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• pp.596-600
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• 2011

Thermal degradation behavior of a $WO_3-TiO_2$ monolithic catalyst was investigated in terms of structural, morphological, and physico-chemical analyses. The catalyst with 4 wt.% $WO_3$ contents were prepared by a wet-impregnation method, and a durability test of the catalysts were performed in a temperature range between $400^{\circ}C$ and $800^{\circ}C$ for 3 h. An increase of thermal stress decreased the specific surface area, which was caused by grain growth and agglomeration of the catalyst particles. The phase transition from anatase to rutile occurred at around $800^{\circ}C$ and a decrease in the Brønsted acid sites was confirmed by structural analysis and physico-chemical analysis. A change in Brønsted acidity can affect to the catalytic efficiency; therefore, the thermal degradation behavior of the $WO_3-TiO_2$ catalyst could be explained by the transition to a stable rutile phase of $TiO_2$ and the decrease of specific surface area in the SCR catalyst.

• Transactions on Electrical and Electronic Materials
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• v.6 no.5
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• pp.214-220
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• 2005

The ferroelectric properties of the $Pt/PZT(Pb(Zr,Ti)O_3)/Pt$ capacitors are severely degraded when they are annealed in hydrogen-containing environment. Hydrogen atoms created by the catalytic reaction of Pt top electrode during annealing in hydrogen ambient penetrate into PZT films and generate oxygen vacancies by the reduction of the PZT films, which is likely to cause the degradation. The degree of hydrogen-induced degradation and the direction of voltage shift in P-E curves of the pre-poled PZT capacitors after annealing in hydrogen ambient is dependent on the polarity of the pre-poling voltage. This implies that oxygen vacancies causing hydrogen induced degradation are generated by hydrogen ions having a polarity. The degraded ferroelectricity of the PZT capacitors can be effectively recovered by the shift of oxygen vacancies toward the Pt top electrode interface during post-annealing in oxygen environment with applying negative unipolar stressing.

• Elastomers and Composites
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• v.52 no.2
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• pp.131-135
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• 2017

Zinc nitrate hexahydrate [$Zn(NO_3){\cdot}6H_2O$] and sodium hydroxide [NaOH] were used as source reagents in the preparation of ZnO nanoparticles in an aqueous solution containing deionized water and ethanol in a ratio of 2:5 (v/v). ZnO nanoparticles were heated in an electric furnace at $700^{\circ}C$ for 2 h under an atmosphere of inert argon gas. The morphological and structural properties of the nanoparticles were characterized by scanning electron microscopy (SEM) and powder X-ray diffractometry (XRD). UV-vis spectrophotometry was used to analyze the photocatalytic degradation of 3-nitrophenol with ZnO nanoparticles as photocatalyst under ultraviolet irradiation at 254 nm. Evaluation of the kinetic of the photo-catalytic degradation of 3-nitrophenol indicated that the degradation of 3-nitrophenol with ZnO nanoparticles obeyed the pseudo-first order reaction rate model.

• Environmental Engineering Research
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• v.24 no.3
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• pp.513-520
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• 2019

In this investigation, nano ZnO was sonochemically synthesized by a novel method using a methionine precursor. A narrow size distribution (41-50 nm) of nano ZnO was achieved that was immobilized on perlite and applied as a catalyst in catalytic ozonation. The catalyst was characterized by fourier transform infrared spectroscopy, BET surface area, and field emission scanning electron microscope. The ozonation of recalcitrant Remazol black 5 (RB5) di-azo dye solution by means of the synthesized catalyst was investigated in a bubble column slurry reactor. The influence of pH values (7, 9, 11), catalyst dosage (8, 12, 15, $20g\;L^{-1}$) and reaction time (10, 20, 30, 60 min) was investigated. Although the dye color was completely removed by single ozonation at a higher reaction time, the applied nanocatalyst improved the dye declorination kinetics. Also, the degradation of the hazardous aromatic fraction of the dye was enhanced five-times by catalytic ozonation at a low reaction time (10 min) and a neutral pH. The second-order kinetics was best fitted in terms of both RB5 color and its aromatic fraction removal. The total organic carbon analysis indicated a significant improvement in the mineralization of RB5 by catalytic ozonation using the nano-ZnO/perlite catalyst.