Photocatalytic oxidation of oxalic acid in dilute aqueous solution, in a fully illuminated fluidized bed reactor

Experimental measurement and modelling of reactive species generation in TiO2 nanoparticle photocatalysis

“…The equations for the variation of the concentration of photogenerated holes, promoted electrons and hydroxyl radicals over time were derived from the literature [17,36,37] and experimental results: $$\frac{dfalse[h^{+}false]}{\mathit{\text{dt}}}=\Phi R-k_{1}false[h^{+}false]false[{\mathit{\text{OH}}}^{-}false]-{\epsilon }^{D_f-1}{k}_{2}false[h^{+}false]false[e^{-}false]-k_{3}false[h^{+}false]false[{\mathit{\text{OH}}}^{•}false]-true\{k_{R}false[h^{+}false]\frac{K_{A}false[I^{-}false]}{1+K_{A}false[I^{-}false]}true\}$$ $$\frac{dfalse[e^{-}false]}{\mathit{\text{dt}}}=\Phi R-{\epsilon }^{D_f-1}{k}_{2}false[h^{+}false]false[e^{-}false]-k_{4}false[e^{-}false]false[{\mathit{\text{OH}}}^{•}false]-k_{5}false[e^{-}false]false[O_{2}false]$$ $$\frac{dfalse[{\mathit{\text{OH}}}^{•}false]}{\mathit{\text{dt}}}=k_{1}false[h^{+}false]false[{\mathit{\text{OH}}}^{-}false]-k_{3}false[{\mathit{\text{OH}}}^{•}false]false[h^{+}false]-k_{4}false[{\mathit{\text{OH}}}^{•}false]false[e^{-}false]-{k_{6}false[{\mathit{\text{OH}}}^{•}false]}^2-false\{k_{\mathit{\text{TA}}}false[{\mathit{\text{OH}}}^{•}false]false[\text{italicTA}false]false\}$$ in which Φ is the quantum yield of the material and R is the radiation intensity per unit volume. [h + ], [e − ], [OH − ], [OH • ], [I − ], [O 2 ] and [TA] are the molar concentrations of photogenerated holes, promoted electrons, hydroxyl ions, hydroxyl radicals, iodi...…”

Photocatalytic Oxidation of Azo Dyes and Oxalic Acid in Batch Reactors and CSTR: Introduction of Photon Absorption by Dyes to Kinetic Models

“…where k 1, obs and k 0.5, obs represent the apparent rate constant for the reaction of pollutant molecules with •OH radicals and holes, respectively, [OC] denotes the molar concentration of organic content in the system (TOC/12), while q(t) represents the surface coverage by labile complex. Note that sum of surface coverage by both complexes is 1, relating to the assumption that hydroxyl groups and oxygen occupy sites different than the pollutant 12 . Surface coverage during reaction is determined by the following expression, Eq.…”

“…Recent studies imply that the overall photodegradation of oxalic acid occurs due to the combination of two pathways working in parallel. In addition, two kinetic regimes were observed by analyzing the photodegradation reaction rate; fast first order and slow half reaction order kinetics were associated with •OH-attack and direct h + trapping by the adsorbed oxalic acid/oxalate molecules, respectively 11,12 .…”

“…Moreover, the Langmuir-Hinshelwood (L-H) mechanism was successfully applied to describe the kinetics of photocatalytic reaction of a wide range of organic pollutants over illuminated TiO 2 surface 9,12,13 . In the previous work, the authors showed that degradation of pollutant, e.g., dye can be simplified and described as first-order equation 14 .…”

Catalytic water cleaning: materials and transport aspects

“…The intrinsic kinetics are determined for flowrate -independent conversions [60][61][62][63][64][65][66][67][68][69][70][71]. Accepting the reliability of this method to eliminate external mass transport, the question about internal mass transfer remains, which will be present even for thin catalyst layers or for an inevitable degree of aggregation in slurry systems.…”