Catalytic degradation of picric acid by heterogeneous Fenton‐based processes

Abstract

The efficiency of goethite, magnetite and iron powder (Fe0) in catalysing the Fenton-based oxidation of picric acid (PA) in aqueous solution was studied. The effect of pH, hydrogen peroxide concentration, and catalyst type and dosage on treatment efficacy was investigated. The adsorption of PA from aqueous solution by heterogeneous catalysts was also examined. The results demonstrated negligible PA removal in H2O2/alpha-FeOOH and H2O2/Fe3O4 systems independent of process pH, and hydrogen peroxide and catalyst dosage. The PA adsorption effects of both iron oxides turned out to be insignificant for all studied pH values and catalyst dosages. The H2O2/Fe0 system proved efficient at degrading PA, but only under acidic conditions (pH 3). The results indicated that, due to rather fast leaching of ferrous ions from the iron powder surface, PA degradation was carried out mainly by the classic Fenton oxidation mechanism in the bulk solution. The adsorption of PA onto the iron powder surface may also contribute to the overall efficiency of PA degradation.

Degradation of diclofenac in aqueous solution by homogeneous and heterogeneous photolysis

“…The amount of the total dissolved iron in the bulk solution for H 2 O 2 /α-FeOOH system was less than 0.03 mg L -1 after 120 min of oxidation, indicating solely heterogeneous pathway of reaction. Some decrease in H 2 O 2 concentration observed during the goethite catalyzed Fenton-based oxidation is most likely due to partial H 2 O 2 decomposes to oxygen and water at the surface of the heterogeneous catalysts without producing dissolved radicals [10]. Prolonged experiments with overall duration of 24 h resulted in negligible degradation of DCF with less than 5% removal.…”

“…The application of heterogeneous catalyst (e.g. naturally occurring minerals) in the Fenton treatment overcomes the above-mentioned problems and results in extended periods of catalyst life without requiring regeneration or replacement, in easy removal of the catalyst from the treated water by sedimentation or filtration, and in Fenton-like reactions over a wide range of pH value [10]. The heterogeneous Fentonbased processes involving naturally occurring minerals (hematite a-Fe 2 O 3 , goethite a-FeOOH, magnetite Fe 3 O 4 , etc.)…”

“…As to the heterogeneous Fenton process, the goethite catalysed Fenton-based reaction is a surface controlled process that depends on H 2 O 2 concentration, on the iron mineral surface area and on other system parameters (pH, etc.). The overall heterogeneous reaction will include various steps such as diffusion of chemicals to the surface, surface complex formation, actual electron transfer, desorption of products, and regeneration of the reactive sites [10].…”

Catalytic wet peroxide oxidation of aniline in wastewater using copper modified SBA-15 as catalyst

“…Therefore, in the past decades, different chemical treatment technologies have been developed, and advanced oxidation processes (AOPS) such as Fenton oxidation [4], ozone oxidation [5] and UV oxidation [6] have been extensively studied on aniline oxidation. The use of hydrogen peroxide as a kind of clean oxidizing agent in the presence of catalyst in different oxidation reactions has been wide studied [7,8].…”

Reuse of Ferric Sludge by Ferrous Sulfide in the Fenton Process for Nonylphenol Ethoxylates Wastewater Treatment

“…Various heterogeneous catalysts have been developed, such as natural minerals [5], iron-containing clays [6], iron immobilized on solid support [7] and zero-valent [8] [9].…”