Transformation of m-aminophenol by birnessite (δ-MnO2) mediated oxidative processes: Reaction kinetics, pathways and toxicity assessment

Degradation of Sulfamethoxazole by Manganese(IV) Oxide in the Presence of Humic Acid: Role of Stabilized Semiquinone Radicals

“…The pH of reaction solutions was controlled with acetate buffer (10−50 mM) for pH 4.8−6.0 and borate buffer (10−50 mM) for pH 7.0−8.7. Previous studies confirmed that there were negligible effects of acetate buffer38 and borate buffer50 on the birnessite/phenol system. Samples were withdrawn at specific time intervals, filtered through a PTFE membrane filter head (0.22 μm), and tested immediately by the HPLC method to measure residual concentrations of SMX.…”

“…34,35 The role of semiquinone radicals (SQ • ) and other intermediates in abating SMX may be overlooked. During MnO 2 oxidation, phenol, 15,36 aniline, 37,38 and thiol pollutants 39,40 may be transformed to organic radicals via single electron oxidation to initiate a radical−radical coupling process or polymerization. This process may be strengthened by coexisting humic constituents.…”

MnO2‐Based Materials for Environmental Applications

“…MnO 2 ‐based materials have shown enormous potential applications in the removal of organic pollutants in various wastewater treatment technologies, including adsorption, catalytic ozonation, photocatalytic oxidation, electrocatalytic oxidation, peroxymonosulfate oxidation, catalytic filtration, and energy harvesting galvanic cell technologies. So far, MnO 2 ‐based materials have shown superior performances in the removal of various organic pollutants in water, such as dye (methylene blue, [ 359–361 ] methyl orange, [ 362,363 ] Rhodamine B, [ 309,364 ] Congo red, [ 365 ] acid fuchsin dye, [ 218 ] crystal violet dye, [ 366 ] acid red 73, [ 367 ] neutral red, [ 368 ] and tartrazin yellow [ 369 ] ), phenolic pharmaceuticals (phenol, [ 66,325,342,370–372 ] bisphenol A, [ 99,275,373–378 ] ibuprofen, [ 295 ] tetrabromobisphenol A, [ 379 ] benzophenone‐3, [ 216 ] 2,4‐dichlorophenol, [ 380 ] 4‐chlorophenol, [ 381 ] and 4‐nitrophenol [ 382 ] ), antibiotics (tetracycline, [ 383 ] ceftiofur, [ 243 ] and lomefloxacin [ 243 ] ), as well as ammonia borane, [ 384 ] amides, [ 385 ] lignin, [ 386 ] peroxymonosulfate, [ 237 ] 17 β‐Estradiol, [ 249 ] m ‐aminophenol, [ 387 ] carbamazepine, [ 388 ] dichloroacetic acid, [ 389 ] p ‐arsanilic acid, [ 390 ] phenylarsonic acids, [ 391 ] m ‐cresol, [ 288 ] oxalic acid, [ 392 ] ciprofloxacin, [ 393,394 ] phenanthrene, [ 246 ] norfloxacin, [ 291 ] etc. ( Table 2 ).…”

Impact of Mn2+ in bisphenol A degradation by chelating agents-assisted manganese dioxide: Mechanism understanding and efficiency evaluation

“…The influence of Mn 2+ on the reactivity of manganese dioxides has been investigated. The impact of Mn 2+ can be described from several aspects including transforming the crystal structure of MnO that the kinetic constant of m-aminophenol degradation was decreased from 1.04 10 -3 M -1 min -1 to 0.84 10 -3 M -1 min -1 with the addition of Mn 2+ from 0 to 7 mM [22]. Therefore, the treatment of organic pollutants by MnO 2 in the presence of metal ions such as Mn 2+ is a challenge.…”