Titanium dioxide surface modified with both palladium and fluoride as an efficient photocatalyst for the degradation of urea

Kim, Hyoung-il,Kim, Kitae,Park, Soona,Kim, Wooyul,Kim, Seungdo,Kim, Jungwon Elsevier 2019 Separation and purification technology Vol.209 No.-

<P><B>Abstract</B></P> <P>TiO<SUB>2</SUB> surface modified with both Pd nanoparticles and fluorides (F-TiO<SUB>2</SUB>/Pd) was prepared and applied as a photocatalyst in the degradation of urea. Various surface analysis techniques, including X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy, and energy-dispersive X-ray spectroscopy, were used to verify the coexistence of Pd nanoparticles and fluorides on the surface of TiO<SUB>2</SUB> in F-TiO<SUB>2</SUB>/Pd. F-TiO<SUB>2</SUB>/Pd showed a higher photocatalytic activity than those of bare TiO<SUB>2</SUB> and single-component-modified TiO<SUB>2</SUB> photocatalysts such as fluorinated TiO<SUB>2</SUB> (F-TiO<SUB>2</SUB>) and Pd-loaded TiO<SUB>2</SUB> (Pd/TiO<SUB>2</SUB>). The higher urea degradation efficiency of F-TiO<SUB>2</SUB>/Pd is ascribed to the enhanced production of hydroxyl radicals (<SUP> </SUP>OH) by the synergistic action of the surface Pd and fluoride. Pd nanoparticles and fluorides facilitate the transfer of valence band holes (h<SUB>vb</SUB> <SUP>+</SUP>) and their reaction with water molecules, respectively, synergistically enhancing the production of <SUP> </SUP>OH. The photocatalytic activity of F-TiO<SUB>2</SUB>/Pd for the degradation of urea increased upon increasing the fraction of the fluorinated TiO<SUB>2</SUB> surface, which is higher at higher fluoride concentrations and lower pH. Although Pt/TiO<SUB>2</SUB> showed higher photocatalytic activity for the degradation of urea than those of Pd/TiO<SUB>2</SUB> and Au/TiO<SUB>2</SUB>, the strong positive effect of fluoride complexation was only exhibited by Pd/TiO<SUB>2</SUB> (a slight positive effect and a negative effect were observed for Au/TiO<SUB>2</SUB> and Pt/TiO<SUB>2</SUB>, respectively). As a result, the degradation of urea proceeded more rapidly in a UV-irradiated suspension of F-TiO<SUB>2</SUB>/Pd than when any of other photocatalysts (i.e., bare TiO<SUB>2</SUB>, Pd/TiO<SUB>2</SUB>, F-TiO<SUB>2</SUB>, Au/TiO<SUB>2</SUB>, F-TiO<SUB>2</SUB>/Au, Pt/TiO<SUB>2</SUB>, and F-TiO<SUB>2</SUB>/Pt) were used under the same conditions. The first-order degradation rate constants (<I>k</I>) of urea depending on the type of TiO<SUB>2</SUB> were as follows: 0.097 h<SUP>−1</SUP> for bare TiO<SUB>2</SUB>, 0.158 h<SUP>−1</SUP> for Pd/TiO<SUB>2</SUB>, 0.151 h<SUP>−1</SUP> for F-TiO<SUB>2</SUB>, 0.351 h<SUP>−1</SUP> for F-TiO<SUB>2</SUB>/Pd, 0.173 h<SUP>−1</SUP> for Au/TiO<SUB>2</SUB>, 0.223 h<SUP>−1</SUP> for F-TiO<SUB>2</SUB>/Au, 0.240 h<SUP>−1</SUP> for Pt/TiO<SUB>2</SUB>, and 0.165 h<SUP>−1</SUP> for F-TiO<SUB>2</SUB>/Pt, respectively. In addition, F-TiO<SUB>2</SUB>/Pd proved to be stable in repeated urea degradation cycles.</P> <P><B>Highlights</B></P> <P> <UL> <LI> TiO<SUB>2</SUB> surface modified with both Pd nanoparticles and fluorides is prepared. </LI> <LI> F-TiO<SUB>2</SUB>/Pd shows superior photocatalytic activity for the degradation of urea. </LI> <LI> Synergistic action of surface Pd and fluoride markedly enhances the production of <SUP> </SUP>OH. </LI> <LI> Fluoride complexation on Pd/TiO<SUB>2</SUB> is more efficient than that on Au/TiO<SUB>2</SUB> and Pt/TiO<SUB>2</SUB>. </LI> <LI> F-TiO<SUB>2</SUB>/Pd is stable in repeated urea degradation cycles. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Fugitive Emission Model of HFC-134a from Automobile Air Conditioning Systems

( Seungdo Kim ),( Eui-kun Kim ),( Suna Kim ) 한국폐기물자원순환학회 2023 I-CIPEC Vol.2012 No.0

승용차 냉방장치로부터의 온실가스 냉매인 HFC-134a 탈루배출모델에 대한 연구

김승도(Seungdo Kim),김순아(Suna Kim),김의건(i-Kun Kim) 한국대기환경학회 2012 한국대기환경학회지 Vol.28 No.5

Catalytic co-pyrolysis of epoxy-printed circuit board and plastics over HZSM-5 and HY

Kim, Young-Min,Han, Tae Uk,Kim, Seungdo,Jae, Jungho,Jeon, Jong-Ki,Jung, Sang-Chul,Park, Young-Kwon ELSEVIER 2017 JOURNAL OF CLEANER PRODUCTION Vol.168 No.-

<P><B>Abstract</B></P> <P>The catalytic co-pyrolysis of epoxy-printed circuit board (e-PCB) and thermoplastics, high density polyethylene (HDPE) and polypropylene (PP), over HZSM-5 and HY was performed using a thermogravimetric analyzer and pyrolyzer-gas chromatography/mass spectrometry. The catalytic pyrolysis of e-PCB over both HZSM-5 and HY eliminated the brominated compounds, mainly bromo-phenols and -bisphenol As, to some extent. The co-feeding of HDPE and PP on the catalytic pyrolysis of e-PCB over both HZSM-5 and HY revealed different debromination efficiencies due to the properties of the thermoplastics and catalysts. A comparison of HY(80) and HZSM-5(80) with the same SiO<SUB>2</SUB>/Al<SUB>2</SUB>O<SUB>3</SUB> ratio (80) revealed HY(80) had a better elimination efficiency of brominated compounds during the catalytic co-pyrolysis of e-PCB and HDPE or PP because of its larger pore size than HZSM-5(80). The lowest bromine content was achieved when HDPE and HY(30) were used as the co-feeding reactant and catalyst on the pyrolysis of e-PCB due to the large pore size and high acidity of HY(30), allowing the easier diffusion of large molecular brominated bisphenol A and HDPE molecules into the pores of the catalyst and efficient catalytic intermolecular reactions in the pores of the catalyst. The catalytic co-pyrolysis of e-PCB and HDPE over HY(30) also produced large amounts of mono-aromatic hydrocarbons and mono-phenol, which can be used as fuels or chemical feedstock.</P>

Catalytic Pyrolysis of Organosolv and Klason Lignin Over Al-SBA-15

Kim, Young-Min,Kang, Bo Sung,Han, Tae Uk,Kim, Seungdo,Jung, Sang-Chul,Kim, Sang Chai,Jeon, Jong-Ki,Park, Young-Kwon American Scientific Publishers 2018 Journal of Nanoscience and Nanotechnology Vol.18 No.2

<P>The catalytic pyrolysis of two types of lignin, organosolv and klason lignin, which were extracted from miscanthus, over Al-SBA-15 was carried out using a thermogravimetric (TG) analyzer and a pyroyzer-gas chromatography/mass spectrometry (Py-GC/MS). Although Al-SBA-15 has weak acidity, the large molecular phenolic pyrolyzates of lignin were converted effectively into small molecular phenols and aromatic hydrocarbons due to the large pore size of Al-SBA-15. Compared to klason lignin, organosolv lignin produced larger amounts of valuable chemicals, such as mono-phenol, mono-aromatics, and furans, by catalytic pyrolysis over Al-SBA-15.</P>

<i>In-Situ</i> Catalytic Pyrolysis of Dealkaline Lignin Over MMZ-H<i>β</i>

Kim, Young-Min,Park, Rae-su,Lee, Eun-Hwa,Jeon, Jong-Ki,Kim, Sang Chai,Jung, Sang-Chul,Kim, Seungdo,Park, Young-Kwon American Scientific Publishers 2017 Journal of Nanoscience and Nanotechnology Vol.17 No.4

<P>In-situ catalytic pyrolysis of dealkaline lignin (DL) over MMZ-H beta was performed using a pyrolyzergas chromatography/mass spectroscopy for the first time. Non-catalytic pyrolysis of DL mainly produced large amounts of phenolics such as mono-phenol, alkylphenols, guaiacols, eugenols, and vanillin. By applying MMZ-H beta, the amounts of these phenolics were dramatically decreased with the increase of aromatics such as benzene, toluene, ethylbenzene, xylenes, and naphthalenes. The higher conversion efficiency from phenolics to aromatics was obtained by increasing the catalyst to DL ratio from 1/1 to 5/1.</P>

하수처리를 위한 전기화학 반응의 적용 : 최적처리조건의 결정;Determination of Optimal Treatment Conditions

김성호,김승도,신화섭,김영관,전양근 江原大學校 附設 環境硏究所 1999 環境硏究 Vol.16 No.-

본 연구의 목적은 전기화학방식의하수처리에 대한 적용 가능성을 검토하고, 주요 운전인자인전압, COD 부하량, pH, 전기전도도, 반응시간 등의 최적 처리조건을 결정하는데 있다. 각 웅전인자의 변화에 따른 COD의 처리효율을 비교 · 검토하여 최적조건을 도출하였으며, 대부분의 실험은 시간에 따른 COD의 변화를 측정할 수 있는 회분식 반응기를 사용하였고, COD 부하량의 영향을 평가하기 위해서는 체류시간을 변하시키면서 실험이 가능한 연속식 반응기를 사용하였다. 최적 조건은 전압 25V, COD 부하량은 약 160g COD/㎡ · day, pH는 중성범위, 전기전도도는 1000~1300㎲/㎝, 반응시간은 10분으로 나타났다. 전기응집반응이 탁월하여 불용성 COD 는 10분만에 90%이상이 제거되었으며, 대표적 응집제인 alum 100ppm을 투여한 경우보다 처리효율이 약 20 % 정도 향상되었다. 전기화학반응은 불용성 COD의 농도가 높은 하수처리 등에 적적한 것으로 판단되며 처리 시간이 빠르고, 경제성도 뛰어나 향후 하수처리기술로서 주목을 받게 될 것으로 판단된다. This research was carried out to test the feasibility of electrochemical method in sewage treatment and to determine the optimal conditions of operating parameters including applied voltage. COD loading. pH. Conductivity. And reaction time. They were determined based on the COD removal efficiency either by batch reactor operation or by continuous flow reactor operation. For monitoring the variation of COD with time a batch reactor was used, and continous flow reactor was operated at various detention times to estimate the effect of COD loading. The optimal applied voltage, COD loading, and conductivity was found 25V, approximately 160g COD/m² · day, and 1,000~1,300㎲/㎝, respectively. The appropriate pH value for proper operation was in neutral range. This process achieved over 90% of insoluble COD within 10min of reaction, and this efficiency was about 20% greater than when 100ppm alum solution was used for coagulation. It is expected that this electrocoagulation process may be best suited for treating gewage with high insoluble COD content. Good treatment efficiency and low operating cost could make this process gain an increased attention in the field of sewage treatment in not too distant future.

Peak Separation Method for Estimating Apparent Kinetic Parameters of Dehydrochlorination Reactions of PVC: Independent Reactions

Seungdo Kim,In-Hee Hwang,Yeong-Kwang Kim 한국공업화학회 2004 Journal of Industrial and Engineering Chemistry Vol.10 No.3

Investigation on Health Effects of an Abandoned Metal Mine

Kim, Soyeon,Kwon, Ho-Jang,Cheong, Hae-Kwan,Choi, Kyungho,Jang, Jae-Yeon,Jeong, Woo-Chul,Kim, Dae-Seon,Yu, Seungdo,Kim, Young-Wook,Lee, Kwang-Young,Yang, Seoung-Oh,Jhung, Ik Jae,Yang, Won-Ho,Hong, Yun- The Korean Academy of Medical Sciences 2008 JOURNAL OF KOREAN MEDICAL SCIENCE Vol.23 No.3

<P>To investigate potential health risks associated with exposure to metals from an abandoned metal mine, the authors studied people living near an abandoned mine (n=102) and control groups (n=149). Levels of cadmium, copper, arsenic, lead, and zinc were measured in the air, soil, drinking water, and agricultural products. To assess individual exposure, biomarkers of each metal in blood and urine were measured. β<SUB>2</SUB>-microglobulin, α<SUB>1</SUB>-microglobulin, and <I>N</I>-acetyl-beta-glucosaminidase and bone mineral density were measured. Surface soil in the study area showed 2-10 times higher levels of metals compared to that of the control area. Metal concentrations in the groundwater and air did not show any notable differences between groups. Mean concentrations of cadmium and copper in rice and barley from the study area were significantly higher than those of the control area (<I>p</I><0.05). Geometric means of blood and urine cadmium in the study area were 2.9 µg/L and 1.5 µg/g Cr, respectively, significantly higher than those in the control area (<I>p</I><0.05). There were no differences in the levels of urinary markers of early kidney dysfunction and bone mineral density. The authors conclude that the residents near the abandoned mine were exposed to higher levels of metals through various routes.</P>

Peak Separation Method for Estimating Apparent Kinetic Parameters of Dehydrochlorination Reactions of PVC : Independent Reactions

Kim, Seungdo,Hwang, In-Hee,Kim, Yeong-Kwang 한국공업화학회 2004 Journal of Industrial and Engineering Chemistry Vol.10 No.3

This research was designed to develop a separation method for partially overlapped peaks on derivative therm ogravimetry (DTG) curves and to apply this technique to estimate the dehydrochlorination kinetics of PVC (Polyvinyl Chloride). It was assumed that two peaks might be responsible for the independent dehydrochlorination reactions of two PVC compounds. Dehydrochlorination kinetics of PVC were inves- tigated using a thermogravimetric analysis (TGA) system at heating rates of 0.75, 1, and 1.25 Wmin under a nitrogen atmosphere. A key hypothesis for applying the separation method was that, under dynamic operations, there would be a unique temperature region in which each compound would decompose uniquely. Firstly, the apparent kinetic parameters and initial mass of the thermally-more-stable PVC compound were estimated from the partial DTG curve in the range where only this compound might decompose. Then, the dehydrochlorination kinetics of the thermally-less-stable PVC compound were elucidated by analyzing its TGA curve that was derived by subtracting the TGA curve of the more-stable PVC compound from the original curve. It is essential to separate the overlapped peaks on the DTG curves to accurately interpret the kinetics of the independent reactions. This separation technique can be applied to analyze the kinetic parameters of two independent reactions provided that there are unique temperature regions in which each compound decomposes solely.