Kinetic modeling of wet peroxide oxidation with a carbon black catalyst

The pH effect on the kinetics of 4-nitrophenol removal by CWPO with doped carbon black catalysts

“…Including the protons concentration in the appearance rate is just like modelling the lumped acids. Taking into account previous reports [32,40], as well as the above discussion about the reaction intermediates resulting from the oxidation of 4-NP (4-NC and carboxylic and nitric acids), a generalized reaction pathway is proposed (Fig. 4), where the assumption of the lumped acids is placed in evidence.…”

“…A kinetic study was done following the methodology considered in a previous work dealing with the CWPO of phenol at the initial pH of 3.5 (without variation of pH) [32,55,56]. The production rate, as r (mmol•h −1 g −1 ) of each given species i inside the batch-reactor was expressed considering a constant volume system, as shown in Eq.…”

“…The catalytic activity of the DCBs was assessed in the CWPO of 4-NP and compared to the non-catalytic wet peroxide oxidation (WPO) process. Pure adsorption contribution to the overall 4-NP uptake was not determined, since it was verified previously that it is negligible [32,33]. The evolution of 4-NP and H 2 O 2 concentrations against reaction time were depicted in Fig.…”

“…However, the Fenton process requires the recovery of the Fe catalyst at the end of treatment and a rigorous pH control to efficiently run the process. Within this context, catalytic wet peroxide oxidation (CWPO) appears more advantageous AOP [30,31], since run with a heterogeneous catalyst which can be recovered after the process [11,32,33]. However, most of the studies regarding the CWPO of 4-NP deals with the development of catalysts containing iron, such as hybrid magnetic graphitic nanocomposites [34], nano-magnetite [35], fly ash [36], ferrous hydroxide colloids [37], Fe/Cu/Zr-clays [38], or carbon nanotubes produced onto iron catalysts [34][35][36][37]39].…”

“…The current work deals with the development of a kinetic model for the CWPO of 4-NP, allowing the prediction of the effect of the aqueous solution pH evolution with reaction time. Non-porous metal-free carbon black (CB) is used as pristine material, since it was found to be an efficient and stable catalyst for CWPO [32] and since it is possible to increase its catalytic activity by proper doping with P, N and B, as previously demonstrated [33].…”