Removal of persistent textile dyes from wastewater by Fe(ii)/H2O2/H3NOH+ integrated system: process performance and limitations?

Environmental Science: Advances Pub Date: 2022-04-06 DOI: 10.1039/D2VA00011C

Abstract

With the objective of establishing an overview of the limits of hydroxylamine-induced acceleration of the Fenton process, the impact of a wide range of processing conditions and water matrix compositions (water quality) on the degradation of persistent textile dyes is revealed in this study. The co-use of Fenton reagents and hydroxylamine in its protonated form (H3NOH+) enabled the rapid removal of dyes, with a yield improvement of more than 40% compared to the not using H3NOH+. H3NOH+ broadened the Fenton working pH up to pH 5, where higher degradation efficacy is achieved to that at pH 3. The gap between the Fenton-H3NOH+ and Fenton systems in term of dye removal increases with increasing dosages of reactants (i.e., H3NOH+, H2O2, Fe(II) and dye) and solution pH (2–5). While sulfate and nitrite ions (up to 10 mM) did not affect the efficiency of the process in the presence or absence of H3NOH+, chloride greatly hindered the Fenton process (60%) while minimally affecting dye removal by the Fenton-H3NOH+ system. The Fenton-H3NOH+ system maintained better degradation performance for the breakdown of Basic Fuchsin (BF) in natural mineral water and treated wastewater. However, the degradation efficiencies in sea and river waters are substantially reduced, with just 61 and 58% elimination being reached, respectively. However, the ternary system outperforms the Fenton process alone in all of the studied water matrices. The findings of this work broaden our understanding of the application of hydroxylamine in the Fenton process and highlight the limitations of its influence in boosting the breakdown efficiency of textile dye contaminants.

Graphical abstract: Removal of persistent textile dyes from wastewater by Fe(ii)/H2O2/H3NOH+ integrated system: process performance and limitations
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