Bionanocomposites for Magnetic Removal of Water Pollutants

Abstract

Magnetic separation in water remediation processes is of great interest in current environmental technologies. An important aspect in this field has been the development of efficient sorbents for water purification units, namely by exploiting other functionalities that might originate more sustainable technologies. This chapter describes the state-of-art on the chemical preparation of magnetic sorbents comprising inorganic particles and biopolymer matrices. Fundamental aspects related to nanoparticle synthesis of iron oxides and nanomagnetism will be first addressed. The use of these particles in biopolymers matrices such as polysaccharides will be then reviewed as an innovative strategy aiming at production of eco-friendly sorbents for magnetic separation.

Removal of As(V) from aqueous solutions using calcium-alginate microspheres with encapsulated iron nanoparticles

“…However, people who consume water with amounts greater than 0.05 mg/L of this metalloid have shown lesions such as hyperkeratosis, changes in pigmentation, various types of cancer, like skin, lung, kidney, liver, and bladder (Habuda-Stanić& Nujić2015;Palma-Lara et al 2020). The chemistry of this element includes the existence of different oxidation states, with the species As(III) and As(V) being the most commonly found in natural waters, depending on their pH value (Sousa et al 2015). Arsenite is more toxic and mobile than arsenate, but arsenate in contaminated groundwater is more common, particularly in shallow aquifers.…”

“…Based on this evidence, alternative technologies have been developed in recent years to verify the high affinity of Fe(III) for arsenic ions in various adsorbents (Swain et al 2013;Lalhmunsiama et al 2017;Zang et al 2021). However, it has also been reported that nanoscale Fe intensifies its functional and surface properties, providing bonds with functional groups that favor adsorption (Habuda-Stanić& Nujić2015;Sousa et al 2015). In addition, the use of polymeric adsorbents with proven efficacy in the removal of As(V), such as calcium alginate (Chowdhury et al 2019), provides advantages for its use as a support for iron nanoparticles (FeNPs), which also provides the advantage of nanoparticle recovery, and as an adsorbent for these ions.…”

Carrageenan-grafted magnetite nanoparticles as recyclable sorbents for dye removal

“…Furthermore, enhanced adsorption and selectivity of the MNPs toward target pollutants can be achieved by chemical modification of the MNPs' surface with specific chemical groups that will interact with the pollutant compounds (Sousa et al 2015;Tavares et al 2013). Example of this approach is the surface modification of the particles with polysaccharides that contain in their structure chemical functionalities with affinity for the pollutants, such as chitosan and derivatives (Ngah et al 2011) and alginate (Rocher et al 2008).…”