Pt-catalyzed Ozonation of Aqueous Phenol Solution Using High- gravity Rotating Packed Bed C. C. Chang*, C. Y. Chiu**, C. Y. Chang*, D. R. Ji*, J. Y. Tseng*, W. K. Tu*, C. F. Chang***, Y. H. Chen**** and Y. H. Yu* * Graduate Institute of Environmental Engineering, National Taiwan University, Taipei 106, Taiwan (E-mail: d92541005@ntu.edu.tw; cychang3@ntu.edu.tw; jdr0826@gmail.com; f85541003@ntu.edu.tw; f92541111@ntu.edu.tw; yuehwayu@ntu.edu.tw) ** Department of Cosmetic Science and Application, Lan-Yang Insititute of Technology, I-Lan 261, Taiwan (E-mail: cychiu@mail.fit.edu.tw) *** Department of Environmental Science and Engineering, Tunghai University, Taichung 407, Taiwan (E-mail: cfchang@thu.edu.tw) **** Department of Chemical and Material Engineering, National Kaohsiung University of Applied Science, Kaohsiung City 807, Taiwan (E-mail: yhchen@cc.kuas.edu.tw) Abstract In this study, the high-gravity rotating packed bed (HGRPB) was used as a catalytic ozonation (OZ) reactor to decompose phenol. The operation of HGRPB system was carried out in semi-batch apparatus which combines two major parts, rotating packed bed (RPB) and photo-reactor (PR). The RPB consists of a rotor and a stationary housing. The platinum-containing catalyst (Dash 220N) is packed in the RPB to adsorb molecular ozone and the target pollutant of phenol on the surface to catalyze the oxidation. An ultra violet (UV) lamp (applicable wavelength λ = 200-280 nm) is installed in the PR to enhance the self-decomposition of molecular ozone in water to form high reactive radical species. The phenol solution flows outward from the inner edge of the rotor due to the centrifugal force. Gaseous ozone flows inward countercurrently from the outer edge of the packed bed via the pressure-driving force. Different combinations of advance oxidation processes (AOPs) with HGRPB for the degradation of phenol were tested. These include high- gravity OZ (HG-OZ), HG catalytic OZ (HG-Pt-OZ), HG photolysis OZ (HG-UV-OZ) and HG- UV/Pt-OZ (HG-UV-Pt-OZ). The addition of Dash 220N enhances the mineralization efficiency (η TOC ) of phenol significantly. Keywords Ozone; catalyst; high-gravity rotating packed, phenol INTRODUCTION The ozonation (OZ) process has been used in drinking water and wastewater treatment science last century. However, the OZ of organic compounds in solution is limited by gas-liquid mass transfer efficiency and its selective reactivity. The high-gravity rotating packed bed (HGRPB, HG or Higee) was used in this study as a gas-liquid contactor to enhance the mass transfer rate between the phases. The HGRPB can increase the interfacial area while decrease the mass transfer resistance between gas and liquid phases by decreasing the thickness of the liquid film and the size of the droplets [1]. The HGRBP is being developed science 1979 [2]. Recently, the HGRPB is applicable to absorption, adsorption, desorption, distillation, polymer devolatilization, bio-oxidation, reactive crystallization, stripping, extraction and other separation processes [3]. HGRPB also has been used for micro-mixing and emulsion [4]. The values of volumetric gas-liquid mass transfer coefficients achievable in HGRPB are one or two orders of magnitude higher than those in conventional packed beds [5]. Recent studies [6-8] showed that HGRPB has some advantageous characteristics such as 1) fast renewable rate on the surface of packed materials, 2) high gas-liquid mass transfer coefficients, 3) short time to reach steady state, 4) low overflow rate, 5) short hydraulic retention time (HRT) and 6) thin liquid film. Previous studies point out that HGRPB has a higher mass transfer rate in gas-liquid system than conventional gas-liquid contactor. Chen et al. [9] used RPB as well as completely stirred tank reactor (CSTR) as ozone gas-liquid contactor to treat CI Reactive Black 5 (RB5). The results Manuscript Click here to download Manuscript: LET2008_IWA-324_20080331.doc