Electro-chemical removal effects for the pollutants with K-ACFs

오원춘,임창성,Choung-Sung Park,Young-Seak Lee 한양대학교 세라믹연구소 2006 Journal of Ceramic Processing Research Vol.7 No.1

A study of the treatment of wastewater using K-activated carbon fiber (ACF) system followed electrochemical removal was carried out at laboratory scale. Various different types of ACF treated with potassium salts as K sources have been used in this study to investigate the catalytic removal efficiency of pollutants from the wastewater. The electro-chemical removal capacities of K-ACF electrodes were associated with their adsorption properties and were related to physico-chemical properties such as surface area and kind of treated potassium salts, and to reaction time. And, surface morphologies and elemental analysis for the K-ACFs after ECR as a function of time are investigated by SEM and EDX to explain the changes in removal capacities. The K-ACFs were electrochemically reacted with wastewater to investigate the removal efficiencies for the COD, BOD, T-N and T-P. A satisfactory removal performance except results for the T-P removal performance was achieved.

Physical properties of KPACFs and their pH dependence on their T-N and T-P removal

오원춘,Chong-Sung Park,Chang-Sung Lim 한양대학교 세라믹연구소 2006 Journal of Ceramic Processing Research Vol.7 No.4

In this study, the characterizations of powdered activated carbon fiber treated with potassium (KPACFs) systems by nitrogen adsorption, SEM-EDX, UV/VIS, Boehm titration and removal efficiencies of pollutants by variation of pH are presented. From the adsorption and surface analysis, it is shown that the ACF samples prepared by treatment with aqueous solutions containing potassium ions or salts have a more heterogeneous micropore structure. SEM images and EDX spectra show a homogeneous distribution of potassium salts on the large body fiber surface and the presence of C, O and P. Quantitative analyses of surface species including oxygen groups are determined by FT-IR and Boehm’s titration methods. Finally, the color, total nitrogen (TN) and total phosphate (T-P) removal performance of piggery waste dispersed with KPACFs is investigated and these results are acceptable for the final disposal of the treated effluent depending on pH. In this study, the characterizations of powdered activated carbon fiber treated with potassium (KPACFs) systems by nitrogen adsorption, SEM-EDX, UV/VIS, Boehm titration and removal efficiencies of pollutants by variation of pH are presented. From the adsorption and surface analysis, it is shown that the ACF samples prepared by treatment with aqueous solutions containing potassium ions or salts have a more heterogeneous micropore structure. SEM images and EDX spectra show a homogeneous distribution of potassium salts on the large body fiber surface and the presence of C, O and P. Quantitative analyses of surface species including oxygen groups are determined by FT-IR and Boehm’s titration methods. Finally, the color, total nitrogen (TN) and total phosphate (T-P) removal performance of piggery waste dispersed with KPACFs is investigated and these results are acceptable for the final disposal of the treated effluent depending on pH.

Metal elimination effect by sulfuric acid for Ag and Cu pre-treated activated carbon

오원춘,임창성 한양대학교 세라믹연구소 2006 Journal of Ceramic Processing Research Vol.7 No.2

From the results of adsorption, each isotherm shows a distinct knee band, which is characteristic of microporous adsorbents with capillary condensation in micropores. In order to reveal the causes of the differences in adsorption capacity and specific surface area after the samples were washed with various strengths of sulfuric acid, surface morphology and pore structure were investigated by SEM. X-ray diffraction patterns indicated that activated carbon containing metal species show better performance for metal and metal compound removal by post-treatment with acid. The FT-IR spectra of metal-activated carbon samples show that the acid post-treatment was consequently associated with the removal of metals with an increased surface functional group containing oxygen of the activated carbon. The type and quality of oxygen groups are determined on the method proposed by Boehm. For the chemical composition microanalysis of metal-activated carbons transformed by post-treatment with sulfuric acid, samples were analyzed by EDX.

Microstructures and photonic effects of titania dispersed inside/outside carbon nanotube composites derived from different titanium alkoxide precursors

오원춘,Feng-Jun Zhang,임창성,Ming-Liang Chen 한양대학교 세라믹연구소 2010 Journal of Ceramic Processing Research Vol.11 No.4

The comparative microstructures and photonic effects of CNT/TiO2 composites which were derived from pre-oxidized carbon nanotubes and different titanium alkoxide precursors (titanium (IV) n-butoxide (TNB), titanium(IV) isopropoxide (TIP) and titanium(IV) propoxide (TPP)) by a sol-gel method. The composites were characterized by theirBrauer-Emett-Teller surface areas, transmission electron microscopy, X-ray diffraction, and UV-vis absorption spectroscopy. The photoactivity of the prepared materials under UV irradiation was tested using methylene blue (MB) in an aqueous solution. The CNT/TiO2composites derived from the TIP precursor only existed in an anatase state with a very strong intensity, while the CNT/TiO2composites derived from TIP and TPP precursors included a mixed structure of anatase and rutile. The TiO2 particles were embedded into the tubes of CNTs for the CNT/TiO2 composites derived from the precursors with TNB and TIP, while for the CNT/TiO2 composites from TPP the TiO2 particles were only distributed outside the surfaces of the CNTs and partially aggregated. The CNT/TiO2 composites derived from TPP have a higher degradation effect on the MB solution more than that of TNB and TIP as titania precursors. A mechanism of TiO2 particles dispersing inside or outside of the CNT is proposed.

리튬-탄소층간화합물의 Deintercalation에 따른 구조변이와 전기적 성질과의 관계(I) : Li-GFDICs와 Li-PCDICs의 생성에 대하여

오원춘,백대진,고영신,Oh, Won-Chun,Baek, Dae-Jin,Ko, Young-Shin 한국분석과학회 1995 분석과학 Vol.8 No.2

가온 가압법으로 합성한 리튬-흑연섬유간화합물(Li-Graphite Fiber Intercalation Compounds, Li-GFICs)과 리튬-석유코크스층간화합물(Li-Petroleum Cokes Intercalation Compounds, Li-PCICs)을 공기 순환에 의하여 자발적으로 deintercalation시키고, 이 deintercalation의 분해 과정으로 나타나는 Li-GFDICs와 Li-PCICs의 구조를 전기적 성질에 미치는 영향에 대하여 논의하였다. 이에 대한 분석은 X-선 회절과 전기 비저항 측정에 의해 수행되었다. X-선 회절 분석에 의하면 Li-GFDICs의 경우 주로 2 stage가 형성되었고 Li-PCICs의 경우에는 1 stage와 2 stage가 주된 회절선으로 나타났다. 또한 deintercalatlon 반응 결과에 의하면 Li-GFDICs의 경우 5주 이후에, Li-GFDICs의 경우 3주 후에 deintercalation 반응이 각각 멈췄다. 전기 비저항 측정 결과에 의하면 Li-GFDICs의 경우 3주까지는 거의 변화가 없었고 그 후 완만한 상승곡선을 나타내었으며, Li-PCDICs의 경우에는 3주를 정점으로 하향곡선을 나타내었다. 따라서 본 연구결과에 의하면 기질로 사용된 흑연섬유와 석유 코크스의 경우 리튬의 원활한 intercalation-deintercalation 작용이 잘 이루어지므로 두 물질 모두 전지의 양극재로 사용될 수 있을 것으로 기대되어진다. We have discussed on the structural transition and its effect on the electrical property of Li-GFDICs and Li-PCDICs occuring during the deintercalation process of Li-Graphite Fiber Intercalation Compounds(Li-GFICs) and Li-Petroleum Cokes Intercalation Compounds(Li-PCDICs) synthesized under pressure and temperature by spontaneous oxidation by air circulation. The analytical results were obtained by X-ray diffraction and electrical specific resistivity measurements. According to X-ray analysis, we have found that the major stage of Li-GFICs was stage 2 and those of Li-PCICs were stage 1 and stage 2, respectively. And from this results of the deintercalation process, we have found that the deintercalation process did not occur any more after 5th week of Li-GFDICs and after 3rd week of Li-PCDICs. According to the results of the electrical specific resistivity measurements, Li-GFDICs showed little variation to 3rd week and rising in the steady curve after 4th week, while Li-PCDICs showed a rising in the steady curve to 3rd week and a declining curve after 3rd week. Therefore from these results, we can consider that graphite fiber and petroleum cokes as a substrate can be also used as an anode material of battery because they have good intercalation-deintercalation reactivity with lithium.

Synthesis of Expanded Graphite-Titanium Oxide Composite and its Photocatalytic Performance

오원춘,최종근,Feng-Jun Zhang,고유경,Ming-Liang Chen 한국세라믹학회 2010 한국세라믹학회지 Vol.47 No.3

In this study, an expanded graphite-titanium oxide composite is developed from expanded graphite (EG) and titanium n-butoxide (TNB). EG is synthesized by chemical intercalation of natural graphite (NG) and rapid expansion at high temperature. TNB is used as the titanium source. The performances of the prepared EG-TiO2 composite are characterized by BET surface area measurements, scan electron microscope (SEM), X-ray diffraction patterns (XRD) and energy dispersive X-ray analysis (EDX). The catalytic activities of the EG-TiO2 composite are investigated by analysis of the degradation of methylene blue (MB) in aqueous solution under irradiation of UV light. Compared with the pristine TiO2 and activity carbon-TiO2 (AC-TiO2) composite, the EGTiO 2 composite shows very high efficiency against MB solution, and the EG could improve the photocatalytic effect of TiO2 in the MB degradation reaction under the irradiation of UV light.

Formation of TiO2 composites on activated carbon modified by nitric acid and their photocatalytic activity

오원춘,Ming-Liang Chen 한양대학교 세라믹연구소 2007 Journal of Ceramic Processing Research Vol.8 No.5

We have studied a method for the preparation of carbon/TiO2 composites involving the penetration of titanium n-butoxide (TNB) solution into activated carbon. The study has focused on the characterization of the TiO2 obtained in the porous carbon and how increased surface functional groups were created by the acid treatment. The conversion of TNB to TiO2 during the heat treatment must be important for the preparation of carbon/TiO2 composites. From the surface textural properties, both the BET surface area and the total pore volume decreased with the distribution of TiO2 on the activated carbon surfaces after the acid treatment. According to the results of SEM micrographs, titanium complex particles were regularly distributed on the carbon. Also some large clusters were found when the amount of acid treatment was increased. The changes in XRD patterns show typical anatase type on carbon/TiO2 composites prepared with activated carbon modified by nitric acid. The EDX results of carbon/TiO2 composites show the presence of C, O and S with strong Ti peaks. Observation of the absorption bands for the FT-IR spectra shows that the changes for the carbon/TiO2 composite prepared with activated carbon modified by nitric acid are mainly due to the formation of functional groups. Finally, the excellent photocatalytic activity of carbon/TiO2 composites between relative concentration (c/co) of MB and UV irradiation time could be attributed to both effects between photocatalysis of the formation of titania complexes and the adsorptivity of the activated carbon.

Fabrication of Ni-AC/TiO₂ Composites and their Photocatalytic Activity for Degradation of Methylene Blue

오원춘,손주희,Kan Zhang,Ze-Da Meng,Feng-Jun Zhangl,Ming-Liang Chen 한국세라믹학회 2009 한국세라믹학회지 Vol.46 No.1

Activated carbon modified with nickel (Ni-AC) was employed the for preparation of Ni-activated carbon/TiO₂ (Ni-AC/TiO₂) composites. The N₂ adsorption data showed that the composites had a decreased surface area compared with pristine AC. This indicated blocking of the micropores on the surface of the AC, which was further supported by observation via SEM. XRD results showed that the Ni-AC/TiO₂ composite contained a mixed anatase and rutile phase while the untreated AC/TiO₂ contained only a typical single and clear anatase phase. EDX results showed the presence of C, O, and Ti with Ni peaks on the composites of Ni- AC/TiO₂. Subsequently, the photocatalytic effects on methylene blue (MB) were investigated. The improved decomposition of MB showed the combined effects of adsorptions and photo degradation. In particular, composites treated with Ni enhanced the photo degradation behaviors of MB. Activated carbon modified with nickel (Ni-AC) was employed the for preparation of Ni-activated carbon/TiO₂ (Ni-AC/TiO₂) composites. The N₂ adsorption data showed that the composites had a decreased surface area compared with pristine AC. This indicated blocking of the micropores on the surface of the AC, which was further supported by observation via SEM. XRD results showed that the Ni-AC/TiO₂ composite contained a mixed anatase and rutile phase while the untreated AC/TiO₂ contained only a typical single and clear anatase phase. EDX results showed the presence of C, O, and Ti with Ni peaks on the composites of Ni- AC/TiO₂. Subsequently, the photocatalytic effects on methylene blue (MB) were investigated. The improved decomposition of MB showed the combined effects of adsorptions and photo degradation. In particular, composites treated with Ni enhanced the photo degradation behaviors of MB.

Preparation with different mixing ratios of anatase to activated carbon and their photocatalytic performance

오원춘,Ming-Liang Chen,Chang-Sung Lim 한양대학교 세라믹연구소 2007 Journal of Ceramic Processing Research Vol.8 No.2

Pitch/activated carbon/TiO2 composites photocatalysts were prepared by a CCl4 solvent mixing method with different mixing ratios. Since two types of carbon in the particles had porous structures, the pitch/activated carbon/TiO2 composite series showed a good adsorptivity and photo-degradation activity. The result of the textural surface properties demonstrates that there is a slight increase in the BET surface area of composite samples with an increase in the amount of activated carbon. The surface properties seen by SEM present a characterization of the porous texture on the pitch/activated carbon/TiO2 composites and homogenous compositions in the particles for all the materials used. From XRD data, a weak and broad carbon peak of graphene remained and rutile peaks kept some of the anatase structure were observed in the X-ray diffraction patterns for the pitch/activated carbon/TiO2 composites. The EDX spectra for the elemental identification showed the presence of C, O and S with strong Ti peaks. Most of these samples are richer in carbon and Ti metal than any other elements. From the photocatalytic results, the excellent activity of the pitch/activated carbon/TiO2 composites of MB (methylene blue) and UV irradiation time could be attributed to both the effects between the photocatalysis of the supported TiO2 and adsorptivity of the two kinds of carbons. Pitch/activated carbon/TiO2 composites photocatalysts were prepared by a CCl4 solvent mixing method with different mixing ratios. Since two types of carbon in the particles had porous structures, the pitch/activated carbon/TiO2 composite series showed a good adsorptivity and photo-degradation activity. The result of the textural surface properties demonstrates that there is a slight increase in the BET surface area of composite samples with an increase in the amount of activated carbon. The surface properties seen by SEM present a characterization of the porous texture on the pitch/activated carbon/TiO2 composites and homogenous compositions in the particles for all the materials used. From XRD data, a weak and broad carbon peak of graphene remained and rutile peaks kept some of the anatase structure were observed in the X-ray diffraction patterns for the pitch/activated carbon/TiO2 composites. The EDX spectra for the elemental identification showed the presence of C, O and S with strong Ti peaks. Most of these samples are richer in carbon and Ti metal than any other elements. From the photocatalytic results, the excellent activity of the pitch/activated carbon/TiO2 composites of MB (methylene blue) and UV irradiation time could be attributed to both the effects between the photocatalysis of the supported TiO2 and adsorptivity of the two kinds of carbons.

Preparation and Photonic Properties of CNT/TiO₂ Composites Derived from MWCNT and Organic Titanium Compounds

오원춘 한국세라믹학회 2009 한국세라믹학회지 Vol.46 No.3

In this study, CNT/TiO₂ composites derived from various titanium alkoxides and multiwalled carbon nanotubes (MWCNTs) were synthesized and characterized. Surface areas and pore volumes of the CNT/TiO₂ samples showed catastrophic decrease due to deposition of titanium compounds. Scanning electron microscopy (SEM) results indicated that the MWCNTs were homogenously decorated and well-dispersed onto/into the composites without apparent agglomeration of TiO₂ particles. In the X-ray diffraction (XRD) patterns, peaks of anatase and rutile phase were observed. The energy dispersive X-ray spectroscopy (EDX) spectra revealed the presence of major elements such as C and O with strong Ti peaks. According to the photocatalytic results, MB removal by a treatment with CNT/TiO2 composites seems to have an excellent removal effect as order of CTIP, CTNB and CTPP composites due to a photolysis of the supported TiO₂, the radical reaction and the adsorptivity and absorptivity of the MWCNTs.