2019 ⦽ǎႊᔍᖒ⠱ʑྜྷ⦺⫭ ⇹ĥ⦺ᚁݡ⫭ םྙ᧞Ḳ
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Studies on UVC Photo-Fenton Decomposition of Oxalate Waste Depending on the
Reactor Size
Yoon-Ji Park1,*, Hyun-Kyu Lee1, Sae-Binna Lee1, Wonzin Oh1, Sang-June Choi1, Hak-Soo Kim2, Cho-Rong Kim2, and Ki-Chul Kim3
1
Kyungpook National University, 80, Daehak-ro, Buk-gu, Daegu, Republic of Korea 2
KHNP Central Research Institute, 70, Yuseong-daero 1312beon-gil, Yuseong-gu, Daejeon, Republic of Korea 3
KEPCO KPS, 96-1, Gilcheon-gil, Jangan-eup, Gijang-gun, Busan, Republic of Korea *
1. Introduction
To remove the oxalic acid used as a reducing agent in the NPP system decontamination, it is necessary to decompose oxalic acid (H2C2O4) into CO2 and H2O to reduce the amount of waste [1]. Photo-Fenton reaction can be applied to decompose oxalic acid by the combination of H2O2, Fe2+ and UV [2]. In Photo-Fenton reactions, the type of UV lamp and the irradiance density are important factors in determining the decomposition performance. The amalgam lamp has a short wavelength of 257.3 nm, long life and low energy consumption [3]. In this study, the effect of reactor size on decomposition behavior of H2C2O4 was investigated according to energy irradiation density.
2. Experiments
2.1 Materials and Apparatus
Ferrous chloride (FeCl2Â4H2O, Min. 99%), oxalic acid (H2C2O4Â2H2O, Min. 99.5~100.2%), and hydrogen peroxide (H2O2, Min. 28%) were purchased from Ducksan company Korea. The size of UV reactor was varied to 3, 46 L, and details are shown in Table 1.
Table 1. Specification of UVC Photo-Fenton reactors
Type Reactor size (L) Mixing tank volume (L)
UVC Energy Irradiation
Power (W) Power/Reactor volume (W/L) KNU 3 6 34 4.4 CRI 46 45.2 204 2.79 2.2 Method
The experimental method was as following. 2 mM FeCl2 and 30 mM H2C2O4 were mixed in the UV reactor. Then, 30 mM H2O2 was injected into the mixed solution. Residual concentration of H2C2O4 with reaction time was confirmed by TOC analyzer (TOC-V CPH, SHIMADZU, JAPAN).
Table 2. Experimental Conditions
Operation conditions KNU CRI Waste volume (L) 9 60 Reactor volume (L) 3 14.8 Circulation rate_Q (L/min) 0.2 0.005 Reactor residence time (min) 15 2960
3. Results
Fig. 1 and, 2 shows the decomposition rate of oxalic acid by reactor size. The experimental results
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2019 ⦽ǎႊᔍᖒ⠱ʑྜྷ⦺⫭⇹ĥ⦺ᚁݡ⫭םྙ᧞Ḳ show that the decomposition rate of oxalic acid depends on the energy irradiation density regardless of reactor size, circulate rate and waste amount.Fig. 1. Fraction of oxalic acid residual depending on energy irradiation density (KNU).
Fig. 2. Fraction of oxalic acid residual depending on energy irradiation density (CRI).
4. Conclusion
The following conclusions were obtained in comparison of the oxalate Photo-Fenton decomposition behavior by using two different size of reactors.
1. The oxalate decomposition behavior by UVC Photo-Fenton depends on the UVC energy irradiation density, regardless of the size of the UVC reactor.
2. The oxalate decomposition reaction depends on the UVC energy irradiation density (KJ/L) regardless of the circulate rate and waste amount.
ACKNOWLEDGEMENT
This work was supported by the Korea Institute of Energy Technology Evaluation and Planning (KETEP) and the Ministry of Trade, Industry & Energy (MOTIE) of the Republic of Korea (No. 20141510300310).
REFERENCES
[1] H.S. Kim, K.C. Kim, W.Z. Oh et.al., ³Development of Decontamination Technology of Reactor Coolant System and Dismantled Equipment for NPP Decommissioning.´, Final report (2018).
[2] Y. Zuo, Y. 'HQJ ³,URQ ,, catalyzed photochemical decomposition of oxalic acid and generation of H2O2 in atmospheric liquid SKDVHV´&KHPRVSKHUH -2058 (1997). [3] S. Schalk, V. Adam, E. Arnold, K. Brieden, A. Voronov, H.D. Witzke, "UV-lamps for disinfection and advanced oxidation-lamp types, technologies and applications.", IUVA news 8.1, 32-37 (2005).
