Oxidation of PAHs in water solutions by ultraviolet radiation combined with hydrogen peroxide

Abstract

The destruction of three polycyclic aromatic hydrocarbons (PAHs): benzo[a]pyrene, chrysene and fluorene in aqueous solution using advanced oxidation processH2O2/UVwas investigated. The influence of pH, initial hydrogen peroxide and radical scavenger concentrations on the reaction rate was studied. The oxidation reactions most rapidly run in neutral and acidic solution at optimal hydrogen peroxide concentration (ca. 0.01 M). The degradation of benzo[a]pyrene and chrysene follows radical reaction, for fluorene the mechanism is not clear. The rate constants of the hydroxyl radicals and selected PAHs reaction were found to be2.53×1010,9.82×109and2.77×109M−1S−1for benzo[a]pyrene, chrysene and fluorene, respectively

Removal efficiency of anionic surfactants from water during UVC photolysis and advanced oxidation process in H2O2/UVC system

“…For both surfactants, the reaction is not inhibited to the direct photolysis level, what may suggest that an additional reaction ("third pathway") occurs. Similar situation was observed during butylparaben (Błędzka et al 2010) and fl uorene (Ledakowicz et al 1999) degradation in H 2 O 2 /UV system.…”

Oxidation of PAHs in water solution by ozone combined with ultraviolet radiation

“…The level of hydroxyl radical concentrations are in accordance with literature data [11,20] and vary in the range 10 −15 to 10 −12 M. Concerning the applicability of ozonolysis enhanced by UV radiation in PAHs degradation process it is worth to compare this AOP with a separately occurring ozonolysis [25] and photolysis [6]. Figure 7 presents the conversion of studied PAHs depending on the applied oxidation method.…”

“…The process carried out in the presence of hydroxyl radical scavenger suggests that BAP and CHR decomposition follows the radical reaction to some extent, but for FLU it is not so obvious. The behaviour of FLU in the degradation processes using UV radiation [6] ozone [25] and H 2 O 2 /UV [20] system is also different than that of BAP and CHR. Especially, the influence of pH and hydroxyl radical scavenger on the reaction course is distinct, which could indicate a more complicated mechanism of its decomposition.…”

“…The evolution of relative BAP concentration during reaction for various flow rates of ozone gas is shown in Figure 2. Changes in acidity and alkalinity of the reaction medium play a key role in PAHs degradation using O 3 /UV system, because the rates of photolysis [6], ozone solubility and its life time [19] and the rate of radical reactions [20] clearly depend on pH. The process of PAHs decomposition was studied at five pH values: 2, 4, 7, 9 and 12.…”

“…Using literature value of the rate constant for PAHs reaction with • OH radicals [20] the calculations were done according to the formula:…”