Hydroxylamine enhanced treatment of highly salty wastewater in Fe0/H2O2 system: Efficiency and mechanism study

Abstract

• Fe 0 -HA/H 2 O 2 enhanced 7.9 times for tartrazine removal in salty system than Fe 0 /H 2 O 2 . • Fe 0 -HA/H 2 O 2 could widen the application of pH to neutral pH. • Fe 0 -HA/H 2 O 2 could obtain remarkable performance at wide salt concentration levels. • Fe 0 -HA/H 2 O 2 have good suitability for treatment of various types of salty wastewater. This study demonstrated a fast and efficient treatment of highly salty wastewater in a hydroxylamine (HA) enhanced Fe 0 /H 2 O 2 system. The apparent rate constant ( k ) in Fe 0 -HA/H 2 O 2 system could achieve 7.9 times higher than that in Fe 0 /H 2 O 2 system using tartrazine as the target pollutant and Na 2 SO 4 as the model salt. The value of k for removing tartrazine in the salty system by Fe 0 -HA/H 2 O 2 process even 12.7 times higher than that in the conventional system which was attributed to the faster Fe 0 corrosion rate in the salty system. Meanwhile, Fe 0 -HA/H 2 O 2 process could obtain remarkable performance for highly salty wastewater treatment at wide salt concentration levels (0–0.2 M) and could also widen the application of pH to neutral pH. The characterizations by SEM and XPS, the intensity of DMPO–OH adduct signals and detection of Fe 2+ and Fe 3+ ions in different systems confirmed the good performance was owing to the faster Fe 0 corrosion rate in the salty system and acceleration of Fe 3+ /Fe 2+ recycle owing the addition of HA inducing fast catalysis of H 2 O 2 and generation of hydroxyl radicals. Moreover, the value of k for removing tartrazine in various types of salty system by Fe 0 -HA/H 2 O 2 process was 2.9–30.8 times larger than Fe 0 /H 2 O 2 process demonstrating the good suitability of Fe 0 -HA/H 2 O 2 process at various types of salty system. Therefore, this study will shed lights on the reactivity of the Fe 0 -HA/H 2 O 2 system and provide an alternative pathway for removal of salty wastewater.