Hydroxylamine driven advanced oxidation processes for water treatment: A review.

Hydroxylamine (HA) driven advanced oxidation processes (HAOPs) for water treatment have attracted extensive attention due to the acceleration of reactive intermediates generation and the improvement on the elimination effectiveness of target contaminants. In this review, HAOPs were categorized into three parts: (1) direct reaction of HA with oxidants (e.g., hydrogen peroxide (H2O2), peroxymonosulfate (PMS), ozone (O3), ferrate (Fe(VI)), periodate (IO4-)); (2) HA driven homogeneous Fenton/Fenton-like system (Fe(II)/peroxide/HA system, Cu(II)/O2/HA system, Cu(II)/peroxide/HA system, Ce(IV)/H2O2/HA system); (3) HA driven heterogeneous Fe/Cu-Fenton/Fenton-like system (iron-bearing material/peroxide/HA system, copper-bearing material/peroxide/HA system, bimetallic composite/peroxide/HA system). Degradation efficiency of the target pollutant, reactive intermediates, and effective pH range of various HAOPs were summarized. Further, corresponding reaction mechanism was elaborated. For the direct reaction of HA with oxidants, improvement of pollutants degradation was achieved through the generation of secondary reactive intermediates which had higher reactivity compared with the parent oxidant. For HA driven homogeneous and heterogeneous Fe/Cu-Fenton/Fenton-like system, improvement of pollutants degradation was achieved mainly via the acceleration of redox cycle of Fe(III)/Fe(II) or Cu(II)/Cu(I) and subsequent generation of reactive intermediates, which avoided the drawbacks of classical Fenton/Fenton-like system. In addition, HA driven homogeneous Fe/Cu-Fenton/Fenton-like system with heterogeneous counterpart were compared. Further, formation of oxidation products from HA in various HAOPs was summarized. Finally, the challenges and prospects in this field were discussed.

Duan J ，Pang SY ，Wang Z ，Zhou Y ，Gao Y ，Li J ，Guo Q ，Jiang J ... -  《-》

Rapid acceleration of ferrous iron/peroxymonosulfate oxidation of organic pollutants by promoting Fe(III)/Fe(II) cycle with hydroxylamine.

Zou J ，Ma J ，Chen L ，Li X ，Guan Y ，Xie P ，Pan C ... -  《-》

Efficient degradation of sulfamethoxazole by the Fe(II)/HSO(5)(-) process enhanced by hydroxylamine: Efficiency and mechanism.

Fenton or Fenton-like processes have been regarded as feasible methods to degrade a wide variety of contaminants by generating reactive species, but the efficiency is still challenged by the slow transformation from Fe(III) to Fe(II) and pH. This study employed hydroxylamine (HA) to improve the oxidation efficiency of Fe(II)/HSO5- (Fe(II)/PMS) process, by selecting sulfamethoxazole (SMX) as the target compound. The degradation efficiency and mechanism of SMX by the HA/Fe(II)/PMS process were elucidated for the first time. Compared with Fe(II)/PMS process, the HA/Fe(II)/PMS process showed about 4 times higher degradation efficiency of SMX at pH 3.0. The analysis of steady-state concentration of Fe species indicated that HA enhanced the transformation of Fe(III) to Fe(II), sustaining the rapid Fenton-like reactions. Both sulfate radicals and hydroxyl radicals accounted for the degradation of SMX, with the latter regarded as the dominant reactive species. Degradation intermediates of SMX were further analyzed, and three main transformation pathways were thus proposed. The HA/Fe(II)/PMS process was also effective in the removal of SMX and total organic carbon from real pharmaceutical wastewater. This work would broaden the scope of application of Fenton and Fenton-like processes enhanced by HA in contaminants treatment.

Liu G ，Li X ，Han B ，Chen L ，Zhu L ，Campos LC ... -  《-》

The role of Fe dissolution in olivine-hydroxylamine-induced Fenton reaction for enhanced oxidative degradation of organic pollutant.

In this study, a dye pollutant (methyl orange, MO) was effectively oxidized in a hydroxylamine (HA)-assisted Fenton system using various Al/Si/Fe- and Fe-containing minerals. The fastest degradation kinetics of MO were observed in the olivine-HA Fenton system, whereas other Al/Si/Fe and Fe-rich minerals (magnetite and lepidocrocite) demonstrated much slower degradation kinetics. The degradation rate constants were proportional to dissolved Fe(II) quantities in mineral suspensions (R2 = 0.98), indicating the crucial role of dissolved Fe(II) quantity in HA-assisted Fenton reactions. Radical scavenging and electron spin resonance results revealed that MO was dominantly oxidized by ·HO produced in the olivine-HA Fenton system. The continuous production of aqueous Fe(II) via direct Fe(II) dissolution at a pH of 3 and further Fe dissolution from the reductive dissolution of surface Fe(III) by HA was the main driving force for efficient MO degradation. Furthermore, lowering the pH by the addition of hydroxylamine hydrochloride resulted in the effective removal of MO under various pH conditions (3-9), indicating the additional advantage of HA use in Fenton reactions. Liquid chromatography-mass spectroscopy analysis revealed that the cleavage of C-N and C-C bonds, demethylation, hydroxylation, and dehydroxylation were the main processes for MO oxidation in the olivine-HA Fenton system.

Jung J ，Kim J ，Yoon S ，Kumar Reddy PA ，Hwang Y ，Bae S ... -  《-》

Strong enhancement on fenton oxidation by addition of hydroxylamine to accelerate the ferric and ferrous iron cycles.

Chen L ，Ma J ，Li X ，Zhang J ，Fang J ，Guan Y ，Xie P ... -  《-》