Decolorization of C.I. Reactive Red 2 by catalytic ozonation processes.
This study adopted O3, UV/TiO2/O3, O3/Mn(II) and O3/MnO2 systems to assess the decolorization efficiency of C.I. Reactive Red 2 (RR2). The decolorization rate increased with concentrations of Mn(II) and MnO2 in the ranges 0.05-0.1 and 0.05-0.8 g/l, respectively. However, when 0.5-3g/l TiO2 was added, the effect of TiO2 dosage for RR2 decolorization was insignificant in the UV/TiO2/O3 system. At pH 2, the decolorization rate constants of O3, O3/Mn(II) (0.05 g/l), O3/Mn(II) (0.1g/l), O3/Mn(II) (0.15 g/l), O3/MnO2 (0.05 g/l) and O3/MnO2 (0.8 g/l) were 0.816, 2.001, 3.173, 3.087, 1.040 and 1.648 min(-1), respectively. After 5 min of reaction, the decolorization rates followed the order O3/Mn(II)>O3/MnO2>O3>UV/TiO2/O3; however, the TOC removal did not vary among these systems. Adding ethanol reduced the decolorization rate of the UV/TiO2/O3 and O3/MnO2 systems and did not affect the decolorization rate of O3/Mn(II). Decolorization in UV/TiO2/O3, O3/Mn(II) and O3/MnO2 systems is suggested to proceed by mainly radical-, surface- and radical-type mechanisms, respectively. Additionally, direct ozonation cannot be ignored in O3/Mn(II) and O3/MnO2 systems.
Wu
Chung-Hsin
CH
Department of Environmental Engineering, Da-Yeh University, 112 Shan-Jiau Road, Da-Tsuen, Chang-Hua, Taiwan, ROC. chunghsinwu@yahoo.com.tw <chunghsinwu@yahoo.com.tw>
Kuo
Chao-Yin
CY
Chang
Chung-Liang
CL
D002384:Catalysis; D003116:Color; D004396:Coloring Agents / Q000737:chemistry / Q000528:radiation effects; D008345:Manganese / Q000737:chemistry; D017895:Manganese Compounds / Q000737:chemistry; D009282:Naphthalenesulfonates / Q000737:chemistry / Q000528:radiation effects; D016877:Oxidants / Q000737:chemistry*; D010087:Oxides / Q000737:chemistry; D010126:Ozone / Q000737:chemistry*; D014025:Titanium / Q000737:chemistry; D014227:Triazines / Q000737:chemistry / Q000528:radiation effects; D014466:Ultraviolet Rays; D014865:Waste Disposal, Fluid / Q000379:methods; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000528:radiation effects; D018508:Water Purification / Q000379:methods
D004396:Coloring Agents; D017895:Manganese Compounds; D009282:Naphthalenesulfonates; D016877:Oxidants; D010087:Oxides; D014227:Triazines; D014874:Water Pollutants, Chemical; C098610:reactive red 2; C009495:titanium dioxide; D008345:Manganese; C027424:manganese oxide; D010126:Ozone; D014025:Titanium