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TiO2/UV-A 시스템을 이용한 Cu(2)-EDTA의 광촉매 산화반응에서 TiO2 재사용 및 회수
이승목 ( Seung Mok Lee ) 한국물환경학회 2005 한국물환경학회지 Vol.21 No.1
TiO₂-catalyst suspensions work efficiently in Photocatalytic oxidation (PCO) for wastewater treatment. Nevertheless, once photocatalysis is completed, separation of the catalyst from solution becomes the main problem. The PCO of Cu(Ⅱ)-EDTA was studied to determine the reusability of the titanium dioxide catalyst. Aqueous solutions of 10^(-4)M Cu(Ⅱ)-EDTA were treated using illuminated TiO₂ particles at pH 6 in a circulating reactor. TiO₂ was reused in PCO system for treatment or Cu(Ⅱ)-EDTA comparing two procedures: reuse of water and TiO₂ and reuse of the entire suspension after PCO of Cu(Ⅱ)-EDTA. The results are as follows; (ⅰ) Photocatalytic efficiency worsens with successive runs when catalyst and water are reused without separation and filtration, whereas, when TiO₂ is separated from water, the reused TiO₂ is not deactivated. (ⅱ) The TiO₂ mean recovery (%) with reused TiO₂ was 86.4%(1.73g/L). Although the mean initial degradation rate of Cu(Ⅱ)-EDTA and Cu(Ⅱ) was lower than that using fresh TiO₂, there was no significant change in the rate during the course of the three-trial experiment. It is suggested that Cu(Ⅱ)-EDTA could be effectively treated using an recycling procedure of PCO and catalyst recovery. (ⅲ) However, without TiO₂ separation, the loss of efficiency of the PCO in the use of water and TiO₂ due to Cu(Ⅱ), DOC remained from previous degradation and Cu(Ⅱ)-EDTA added to the same suspension was observed after 2 trials, and resulted in the inhibition of the Cu(Ⅱ)-EDTA, Cu(Ⅱ) and DOC destruction.
점감형 흡착탑과 실린더형 흡착탑의 파과특성 비교에 관한 연구
이승목(Seung Mok Lee),김원기(Won Gee Kim) 한국수처리학회 1997 한국수처리학회지 Vol.5 No.4
Adsorption on activated carbon is a very effective treatment method for removal of a broad spectrum of organic chemicals from water supplies and wastewater. Although GAC(granular activated carbon) treatment has been designated as BAT(best available technology) for the removal of several compounds. there are major technical and economic concerns that are forcing utilities to look at other alternatives including with the new regulations. Adsorption is typically carried out in fixed or pulsed beds in columns of constant cross section or in slurry reactors. Recent studies by the principal investigator has shown that adsorption efficiency can be increased substantially by a judicious selection of adsorbent size distribution and a variable cross section for the column. Under identical operating conditions, a reverse stratified tapered bed was shown to increase breakthrough time by 30% to 200% over the conventional cylindrical fixed bed for the solute-adsorbent system studied. Moreover, column pressure drops are lower for the RSTA than the conventional system. Water and wastewater plants processing large volumes of water can realize significant savings in capital and operating costs by utilizing this type of operation. This has wide ranging implications for adsorption technology and its applications in the processing of water and wastewater, hazardous waste and solid waste leachate treatment, and groundwater remediation.
Goethite 현탁액에서 유기산과 인산염의 경쟁적 흡착
이승목(Seung Mok Lee),최봉종(Bong Jong Choi),이태우(Tae Woo Lee) 한국물환경학회 2000 한국물환경학회지 Vol.16 No.3
Competitive adsorption between phosphate and phthalic acid onto goethite was examined in single-sorbate and in binary-sorbate system to determine the extent of competition between phosphate and phthalic acid as a function of pH and ionic strength (0. 0l M NaCl). In order to compare the experimental data, MINTEQA2 program employing the diffuse layer model is used. This is important for a better understanding of the competitive binding of phosphate and phthalic acid in natural systems. Alkalimetric titration was used to characterize the surface acidity of the goethite. The surface acidity constants, pK^s_(a1) and pK^s_(a2), were 4.02 and 7.7, respectively. For phosphate and phthalic acid, typical anionic type of adsorption was noted, respectively. Also, in the binary-sorbate system, the amount adsorbed decreases with an increase in pH. In the experiments with simultaneous complexation of phosphate and phthalic acid, the complexation of phosphate was not influenced by the presence of phthalic acid. On the other hand, the complexation of phthalic acid was decreased by the presence of phosphate. These results suggest that phosphate can significantly influence the adsorption of simple organic acids in natural aquatic systems. Therefore less mobility of phthalic acid is expected than phthalic acid with complexation of phosphate in competitive condition.