The role of metal ions on p-CBA degradation by catalytic ozonation. Issue 5 (October 2019)

• Record Type: Journal Article
• Authors: Psaltou, Savvina; Karapatis, Apostolis; Mitrakas, Manassis; Zouboulis, Anastasios
• Is Part Of: Journal of environmental chemical engineering. Volume 7:Issue 5(2019)
• Publication Date: 2019-10
• Subjects: 2, 4-DCP 2, 4-dichlorophenol -- HPLC High Pressure Liquid Chromatography -- Co Initial concentration of organic compound or of micropollutant -- Ksp Constant of solubility product -- CO3 Ozone concentration -- MeOOH Metaloxy-hydroxide -- Ccat. Catalyst concentration -- NTS 1, 3, 6-naphthalenetrisulfonic acid -- COP Catalytic Ozonation Process -- OH Hydroxyl radicals -- DEHP Bis(2-ethylhexyl)phthalate -- p-CBA p-chlorobenzoic acid; Catalytic ozonation -- Presence of metal ions -- Speciation -- p-Chlorobenzoic acid (p-CBA) -- Water treatment; Chemical engineering -- Environmental aspects -- Periodicals; Environmental engineering -- Periodicals; Chemical engineering -- Environmental aspects; Environmental engineering; Periodicals; 660.0286
• DOI: 10.1016/j.jece.2019.103324
• Languages: English
• ISSNs: 2213-2929

Abstract

Graphical abstract: Highlights: The efficiency of homogeneous COP is related to Ksp of MeOOH formed. Surplus of ozone results in MeOOH formation at nano-scale range. Metals concentration in filtrate (0.45 μm) was equal to their initial values. O3 /Co(II) and O3 /Fe(II) processes significantly improve OH production. Soluble phosphate salts (ZnHPO4 ) diminish the efficiency of ozonation process. Abstract: The homogeneous catalytic ozonation, through the addition of dissolved metal ions, acting as catalysts, was applied for the removal/degradation of small concentrations of p-CBA, used as model micropollutant, from aqueous solutions. For this purpose five different transition metal ions, i.e. Co(II), Fe(II), Mn(II), Ni(II) and Zn(II), were studied at pH 7 and concentrations ranges of 0.25–1 mg/L. It was found that only the application of O3 /Co(II) and O3 /Fe(II) systems can be characterized as effective catalytic ozonation processes. The addition of these metals resulted in 95.5% and 92.5% p-CBA degradation respectively, mainly due to the low solubility of respectively formed oxy-hydroxides (Co(OH)3 and Fe(OH)3 ). These oxy-hydroxides are relatively hydrophobic and positively charged at pH 7, whereas the respective aquatic species, i.e. Co(OH) 2+ and Fe(OH) 2+, can also favor the attraction of negatively charged p-CBA. The optimum conditions for both metal ions were: catalyst concentration 1 mg/L, ozone concentration 2 mg/L and pH value 8, where p-CBA residual concentration was found to diminish below the respective analytical detection limit of 0.025 μM after only 3 min of reaction/oxidation time. Additionally, it was found that the presence of Co(II) and Fe(II) can increase the decomposition of ozone, as well as the production of hydroxyl radicals, hence resulting in faster and more effective p-CBA degradation in comparison to single ozonation (i.e. without the presence of catalytically acting dissolved metal cations).