Iron Based Catalysts Used in Water Treatment Assisted by Ultrasound: A Mini Review

Abstract

The characteristics and performances of catalyst are the key in catalytic ultrasonic treatment of wastewater, and iron based catalysts are known for low cost, high accessibility and safety. This paper reviewed the current research status of iron-based catalysts in water treatment assisted by ultrasound. Zero valent iron, Fe3O4 and iron composited with other metals were analyzed, their behaviors in catalytic sonochemistry were summarized, and the potential catalytic mechanisms were discussed in details. Finally, the future development in this field was proposed.

Insights into the novel application of Fe-MOFs in ultrasound-assisted heterogeneous Fenton system: Efficiency, kinetics and mechanism

“…Although some reduction of ∙OH production happened because of the decomposition of H 2 O 2 , the US cavitation effect compensated for this loss to some extent. It was reported that “hot spot” and “sonoluminescence” phenomenon could be caused by US cavitation effect [14] , [15] , [16] . On one hand, H 2 O 2 could be decomposed into • OH.…”

“…Additionally, because of cavitation effect, H 2 O will be dissociated to • OH and finally produce H 2 O 2 (Eqs. (1)–(3)) [14] , [15] , [16] . ·OH have the ability to attack the target, while H 2 O 2 , as the initiator of the Fenton reaction, will react with Fe(II) or Fe(III) to form more ·OH (Eqs.…”

“…Ultrasound (US) has been developed into an attractive method for organic pollutant removal since 1990 because of its special advantages of safety, cleanness, no secondary pollutants and high penetrability [13] . The “hot spot” theory and “sonoluminescence” phenomenon caused by ultrasonic cavitation lead to the formation of oxygen radicals and the degradation of recalcitrant organic compounds [14] , [15] , [16] . However, US itself has the disadvantages of expensive equipment and large energy input, which seriously limits its application in the actual water treatment process.…”

Synergistic degradation of PNP via coupling H2O2 with persulfate catalyzed by nano zero valent iron

“…However, in case of micrometric ZVI powder applied, 6 the reactions represented by eqn (1) and (2) are slow in nature because of the low material reactivity. 7 Thus, to alleviate the limitation of ZVI/H 2 O 2 system, a number of studies were carried out with incorporating additional setup such as ultrasound and heat 8,9 to speed up the electron transfer process. Besides, nano-scaled ZVI (nZVI) was also frequently studied as an alternative Fenton-like activator because of its much higher reactivity with versatile functions for contaminants removal.…”

Catalytic Liquid-Phase Oxidation of Phenolic Compounds Using Ceria-Zirconia Based Catalysts

“…Although advanced treatment technologies have been studied using UV irradiation, strong oxidizing agents (H 2 O 2 or O 3 ), Fenton reagent (H 2 O 2 + Fe 3+ ), and ultrasound (Rosenfeldt and Linden, 2004; Torres et al, 2008; Nidheesh, 2015; Zhang et al, 2018), they require constant supply of hazardous oxidizing additives, UV irradiation, or ultrasonic irradiation.…”