Enhanced Treatment of Municipal Wastewater Effluents by Fe-TAML/H₂O₂: Efficiency of Micropollutant Abatement

Abstract

Combining iron with a tetraamido-macrocyclic ligand (Fe-TAML) as a catalyst and with hydrogen peroxide (H2O2) as the bulk oxidant is a process that has been suggested for the oxidative abatement of micropollutants during water treatment. In this study, the reactivity of the Fe-TAML/H2O2 system was evaluated by investigating the degradation of a group of electron-rich organic model compounds with different functional groups in a secondary wastewater effluent. Phenolic compounds and a polyaromatic ether are quickly and substantially abated by Fe-TAML/H2O2 in a wastewater effluent. For tertiary amines, a moderate rate of abatement was observed. Primary and secondary amines, aromatic ethers, aromatic aldehydes, and olefins are oxidized too slowly in the investigated Fe-TAML/H2O2 systems to be significantly abated in a secondary wastewater effluent. Trichlorophenol is readily oxidized to chloromaleic acid and chlorofumaric acid, which support a one-electron transfer reaction as the initial step of the reaction between Fe-TAML/H2O2 and the target compound. Fe-TAML/H2O2 does not oxidize bromide to hypobromous acid; however, iodide is oxidized to hypoiodous acid, and as a consequence, the H2O2 consumption is accelerated by a catalytic reaction in iodide-containing water. Overall, Fe-TAML/H2O2 is a rather selective oxidant, which makes it an interesting system for the abatement of electron-rich phenolic-type pollutants.

Accelerating FeIII-Aqua Complex Reduction in an Efficient Solid–Liquid-Interfacial Fenton Reaction over the Mn–CNH Co-catalyst at Near-Neutral pH

“…11 The concentration of H 2 O 2 is detected using a titanium(IV) colorimetric method. 20 Quenching experiments are tested by adding 0.05 mmol of carotene, p-benzoquinone (BQ), isopropanol (IPA), K 2 Cr 2 O 7 , or ethylenediaminetetraacetic acid (EDTA)-2Na to evaluate the possible contributions of 1 O 2 , • O 2 − , • OH, photogenerated electrons (e − ), and photogenerated holes (h + ) in the degradation process. 21 The ROS are reflected by electron paramagnetic resonance spectroscopy (EPR, Bruker A200) with 5 mM 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) in methanol and water as • OH and • O 2 − trapper.…”

“…The Fe II regeneration rate during the reaction is explored by the 1,10-phenanthroline–chromogenic method, and the total dissolved iron concentration is detected via the reduction–chromogenic method . The concentration of H 2 O 2 is detected using a titanium­(IV) colorimetric method . Quenching experiments are tested by adding 0.05 mmol of carotene, p -benzoquinone (BQ), isopropanol (IPA), K 2 Cr 2 O 7 , or ethylenediaminetetraacetic acid (EDTA)-2Na to evaluate the possible contributions of 1 O 2 , • O 2 – , • OH, photogenerated electrons (e – ), and photogenerated holes (h + ) in the degradation process .…”

Toward Selective Oxidation of Contaminants in Aqueous Systems

“…Selective oxidation has been demonstrated to be feasible in both homogeneous and heterogeneous aqueous systems. ,− For example, in homogeneous systems, nonheme N-based macrocyclic ligands (e.g., tetraamidomacrocyclic ligand, phthalocyanine, and derivatives) direct the reaction of iron with H 2 O 2 toward the generation of ferryl species (Fe IV O/Fe V O) rather than traditional HO • . Ferryl species prefer to react with electron-rich pollutants (e.g., phenol, bisphenol A, and tetracycline) with significant resistance to the interference from common coexisting matrices like (bi)­carbonate, sulfate, chloride, and DOM. − Moreover, nonradical pathways, such as coordination mediated intramolecular electron transfer , and interfacial electron transfer, have been explored to selectively degrade target compounds. In heterogeneous systems, selective oxidation could be further realized by the preferential adsorption of targets on the surface of catalysts.…”

Water Purification of Classical and Emerging Organic Pollutants: An Extensive Review

“…Jans et al [65] removed 1-methoxy naphthalene by oxidation with a combination of iron and a tetraamido-macrocyclic ligand (Fe-TAML) and using H 2 O 2 as oxidant reagent. After 15 min, the pollutant concentration in water was reduced by up to 85%.…”

“…Jans et al [65] investigated the possibility of reducing the concentration of water pollutants through an oxidative process using iron with a tetraamido-macrocyclic ligand (Fe-TAML) as a catalyst, together with hydrogen peroxide (H 2 O 2 ). After 15 min of reaction, a phenol removal efficiency equal to 79%, 100%, 98%, 100%, 100% and 100% was obtained in the case of phenol, 4-methyl phenol, 4-chlorophenol, 2,5-dimethyl phenol, 2,4,6-trimethyl phenol and 2,4,6-trichlorophenol, respectively.…”