Mechanistic investigations in sono-hybrid (ultrasound/Fe2+/UVC) techniques of persulfate activation for degradation of Azorubine

Abstract

Persulfate-based oxidation of recalcitrant pollutants has been investigated as an alternative to OH radical based advanced oxidation processes due to distinct merits such as greater stability and non-selective persistent reactivity of SO oxidant species. The present study has attempted to highlight mechanistic features of persulfate-based decolorization of textile dye (Azorubine) using sono-hybrid techniques of activation. Three activation techniques, viz. sonolysis, Fe ions and UVC light and combinations thereof, have been examined. UVC is revealed to be the most efficient decolorization technique. The mechanism of sonolysis (i.e. thermal activation of persulfate in the bubble-bulk interfacial region) is revealed to be almost independent of the mechanism of UVC. Fe activation is revealed to have an adverse interaction with UVC due to scavenging of sulfate radicals by Fe ions. The best hybrid activation technique for persulfate-based degradation and mineralization of Azorubine is UVC+ultrasound. Due to independent mechanisms, degradation and mineralization of the dye obtained with simultaneous application of UVC and ultrasound is nearly equal to the sum of degradation and mineralization obtained using individual techniques.

The application of thermally activated persulfate for degradation of Acid Blue 92 in aqueous solution

“…Several advanced techniques in recent studies have been reported for wastewater treatment containing azo dyes [38][39][40]. Among various implemented methods for dye removal, the advanced oxidation process (AOP) is applied favorably to destroy resistant contaminants.…”

“…([AB92] 0 = 200 mg/L, temperature = 333 K, pH 5, [SPS] 0 = 0.5 mM)subsequently intervenes in a series of reactions (Eqs [31][32][33][35][36][37][38][39][40][41] which create either ClO 3 − or • OH[86][87][88][89]:…”

Sonophotochemical Oxidation of Organic Contaminants in Aqueous Solutions Using Persulfate

“…Однако, окислительные процессы при активации персульфата одновременным воздействием УЗ и УФ (в системе {УФ/УЗ/S 2 O 8 2-}) являются относительно малоисследованными. Ранее установлено, что данная окислительная система является наиболее эффективной для деструкции трихлорэтилена [9] и азорубина [10], а также минерализации модельных стоков красильного производства [11]. Синергический эффект в системе {УФ/УЗ/HSO 5 -} также наблюдался при обесцвечивании водных растворов красителя Прямого оранжевого 26 [12].…”

Fenton oxidation treatment of recalcitrant dye in fluidized bed reactor: Role of SiO2 as carrier and its interaction with fenton's reagent

“…Textile effluents are among the major sources of environmental pollution worldwide. Textile dyes can be toxic to aquatic lives and many of them exhibit carcinogenic characteristics . Due to the presence of azo rings in their structures, dyes are chemically stable and recalcitrant to conventional biological treatment processes .…”