Magnetic nanoparticles: Essential factors for sustainable environmental applications

Abstract

In recent years, there has been an increasing use of engineered magnetic nanoparticles for remediation and water treatments, leading to elevated public concerns. To this end, it is necessary to enhance the understanding of how these magnetic nanoparticles react with contaminants and interact with the surrounding environment during applications. This review aims to provide a holistic overview of current knowledge of magnetic nanoparticles in environmental applications, emphasizing studies of zero-valent iron (nZVI), magnetite (Fe3O4) and maghemite (γ-Fe2O3) nanoparticles. Contaminant removal mechanisms by magnetic nanoparticles are presented, along with factors affecting the ability of contaminant desorption. Factors influencing the recovery of magnetic nanoparticles are outlined, describing the challenges of magnetic particle collection. The aggregation of magnetic nanoparticles is described, and methods for enhancing stability are summarized. Moreover, the toxicological effects owing to magnetic nanoparticles are discussed. It is possible that magnetic nanoparticles can be applied sustainably after detailed consideration of these discussed factors.

Preparation of magnetite-based catalysts and their application in heterogeneous Fenton oxidation – A review

“…However, although graphical evidences have shown the feasibility of separation and recovery of MNPs from water [90,91], no successful real applications have yet been reported [82]. In fact, it has been claimed that the magnetism of MNPs favors their aggregation, thus reducing their dispersibility and activity [77].…”

“…Apart from these concerns, the environmental impacts of the application of MNPs in wastewater treatment require special attention associated to the risk of entering the soil and aquatic systems. Thus, some technical advantages of MNPs, like their small size and high reactivity, represent also potential negative factors by inducing adverse cellular toxic and harmful effects, unusual in micron-sized counterparts [82]. According to several studies [82,[98][99][100], nanoparticles can enter living organisms by ingestion and inhalation and cause toxic effects in organs and tissues.…”

“…Thus, some technical advantages of MNPs, like their small size and high reactivity, represent also potential negative factors by inducing adverse cellular toxic and harmful effects, unusual in micron-sized counterparts [82]. According to several studies [82,[98][99][100], nanoparticles can enter living organisms by ingestion and inhalation and cause toxic effects in organs and tissues. Moreover, the nanoparticles can interact with pollutants in environmental applications and act as carriers of them into aquatic ecosystems [82,[101][102][103].…”

“…According to several studies [82,[98][99][100], nanoparticles can enter living organisms by ingestion and inhalation and cause toxic effects in organs and tissues. Moreover, the nanoparticles can interact with pollutants in environmental applications and act as carriers of them into aquatic ecosystems [82,[101][102][103]. In this context, the immobilization of MNPs onto high-surface-area supports represents an environmentallyfriendly solution which would preserve their unique properties, avoiding their potential negative effects.…”

Synthesis, surface characterization and electrokinetic properties of colloidal silica nanoparticles with magnetic core

“…Core/shell hybrid materials can be composed of different core materials, which are characterized by many interesting properties, such as: magnetic (Hyeon 2002;Deng et al 2008;Kim et al 2008), fluorescence (Tovmachenko et al 2006;Reiss et al 2009), luminescent etc. Especially, superparamagnetic iron oxide nanoparticles (SPIONs) (Salgueirino-Maceira and Correa-Duarte 2007) are promising materials for many biomedical applications, such as hyperthermia treatment , magnetic resonance imaging (MRI) (Schlorf et al 2011), targeted drug delivery systems, especially in cancer treatment Rosena et al 2012;Wahajuddin and Arora 2012), magnetically removable catalysts and, more recently, as magnetically removable adsorbents (Tang and Lo 2013;Zhang et al 2008). Nevertheless, there is a need to modify their surface in order to improve their biocompatibility and biodegradability.…”