Recent Advances in Nanoscale Zero-Valent Iron (nZVI)-Based Advanced Oxidation Processes (AOPs): Applications, Mechanisms, and Future Prospects

Abstract

The fast rise of organic pollution has posed severe health risks to human beings and toxic issues to ecosystems. Proper disposal toward these organic contaminants is significant to maintain a green and sustainable development. Among various techniques for environmental remediation, advanced oxidation processes (AOPs) can non-selectively oxidize and mineralize organic contaminants into CO2, H2O, and inorganic salts using free radicals that are generated from the activation of oxidants, such as persulfate, H2O2, O2, peracetic acid, periodate, percarbonate, etc., while the activation of oxidants using catalysts via Fenton-type reactions is crucial for the production of reactive oxygen species (ROS), i.e., •OH, •SO4−, •O2−, •O3CCH3, •O2CCH3, •IO3, •CO3−, and 1O2. Nanoscale zero-valent iron (nZVI), with a core of Fe0 that performs a sustained activation effect in AOPs by gradually releasing ferrous ions, has been demonstrated as a cost-effective, high reactivity, easy recovery, easy recycling, and environmentally friendly heterogeneous catalyst of AOPs. The combination of nZVI and AOPs, providing an appropriate way for the complete degradation of organic pollutants via indiscriminate oxidation of ROS, is emerging as an important technique for environmental remediation and has received considerable attention in the last decade. The following review comprises a short survey of the most recent reports in the applications of nZVI participating AOPs, their mechanisms, and future prospects. It contains six sections, an introduction into the theme, applications of persulfate, hydrogen peroxide, oxygen, and other oxidants-based AOPs catalyzed with nZVI, and conclusions about the reported research with perspectives for future developments. Elucidation of the applications and mechanisms of nZVI-based AOPs with various oxidants may not only pave the way to more affordable AOP protocols, but may also promote exploration and fabrication of more effective and sustainable nZVI materials applicable in practical applications.

Activated Periodates and Sodium Percarbonate in Advanced Oxidation Processes of Organic Pollutants in Aqueous Media: A Review

“…The use of zero-valent iron as the SPC activator in the Fenton-like processes of organic pollutants degradation is rather reduced to a donor of iron(II) ions 92,93 2Fe 0 + O 2 + 2H + → Fe 2+ + H 2 O 2 (56) with the simultaneous generation of additional amounts of the oxidant -hydrogen peroxide. Therefore, catalysis with the participation of zero-valent iron particles can be attributed to a mixed heterogeneous-homogeneous method of SPC activation.…”

Environmental remediation approaches by nanoscale zero valent iron (nZVI) based on its reductivity: a review

“…19,26 Moreover, nZVI can be easily recycled with an external magnet, and the recycling is still viable even if the nZVI has undergone surface oxidation or surface passivation. 18,27 This character endows nZVI with environmental benignancy and convenient recyclability in the applications of remediation or enrichment, necessitating it as a promising candidate for environmental applications.…”

“… 17 The core–shell structure and Fe-containing oxide layer endow nZVI with distinctive reactive interfaces, which provide plentiful active sites for the reduction, oxidation, and adsorption of contaminants. 18,19 Given these abundant functionalities of nZVI, it has undergone significant extensive studies on environmental remediations, linking to various mechanisms, such as reduction, oxidation, surface complexation, precipitation, which have shown great promise for the treatment of wastewater.…”

PSf Membrane-Impregnated Jute–Copper Nanocomposite as Highly Efficient Dye Removal Material

“…In wastewater treatment, copper nanoparticles can be utilized in various ways, including as catalysts for advanced oxidation processes (AOPs), adsorbents for pollutant removal, and antimicrobial agents for disinfection. , Their ability to efficiently degrade organic pollutants, such as dyes, pharmaceuticals, and industrial chemicals, holds promise for enhancing the efficiency of wastewater treatment systems. Additionally, the antimicrobial properties of copper nanoparticles make them effective in combating microbial contaminants, thereby reducing the risk of waterborne diseases …”