Abstract
To improve the efficiency of the Fe(II)/Fe(III) cycle and continuous reactivity of pyrite, a pyrite/H2O2/hydroxylamine (HA) system was proposed to treat rhodamine B (RhB). The results showed that near-complete decolorization and 52.8% mineralization 50 mg L-1 RhB were achieved under its optimum conditions: HA 0.8 mM, H2O2 1.6 mM, pyrite 0.4 g L-1, and initial pH 4.0. The degradation reaction was dominated by an •OH radical produced by the reaction of Fe2+ with H2O2 in solution. HA primarily had two roles: in solution, HA could accelerate the Fe(II)/Fe(III) cycle through its strong reducibility to enhance RhB decolorization; on the pyrite surface, HA could improve the continuous reactivity of pyrite by inhibiting the oxidation of pyrite. In addition, the dosing manner of HA had a significant effect on RhB decolorization. In addition, the high decolorization and mineralization efficiency of other dye pollutants suggested that the pyrite/H2O2/HA system might be widely used in textile wastewater treatment.
Highlights
Dye effluent released from textile industries is toxic and carcinogenic, which can cause a severe impact on human health and water ecosystems (Brillas & Martínez-Huitle ; Banazadeh et al ; Javaid & Qazi )
13% of rhodamine B (RhB) was removed by the H2O2/HA system, which is because H2O2 can be activated by HA to generate radicals via Equations (7) and (8) (Chen et al b; Wang et al )
The results indicated that the added HA hastens the Fe(III)/Fe(II) cycle and boosts the H2O2 decomposition to produce more OH radicals for RhB decolorization
Summary
Dye effluent released from textile industries is toxic and carcinogenic, which can cause a severe impact on human health and water ecosystems (Brillas & Martínez-Huitle ; Banazadeh et al ; Javaid & Qazi ). Among the existing wastewater treatment technologies, advanced oxidation processes (AOPs) have attracted the attention of many researchers, because AOPs can convert most organic pollutants into smaller compounds or even CO2 due to the highly effective reactive oxygen species (ROS) produced during the reaction process (Bagal & Gogate ; Zhu et al ; Sun et al ). Disulfide (S22À) can act as an electron donor as in Equation (3) on pyrite surfaces to accelerate the Fe(II)/Fe(III) cycle, which is the rate-determining step of the Fenton reaction (Zhao et al ). It is the rate-determining step of pyrite-based AOPs reported by some researchers (Feng et al ; He et al ). It is of great importance to facilitate the Fe(II)/Fe(III) cycle and improve the continuous reactivity of pyrite for pyrite/H2O2 system:
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