Adsorption of Uranium, Mercury, and Rare Earth Elements from Aqueous Solutions onto Magnetic Chitosan Adsorbents: A Review

Abstract

The compound of chitin is the second most important and abundant natural biopolymer in the world. The main extraction and exploitation sources of this natural polysaccharide polymer are mainly crustaceans species, such as shrimps and crabs. Chitosan (CS) (poly-β-(1 → 4)-2-amino-2-deoxy-d-glucose) can be derived from chitin and can be mentioned as a compound that has high value-added applications due to its wide variety of uses, including pharmaceutical, biomedical, and cosmetics applications, food etc. Furthermore, chitosan is a biopolymer that can be used for adsorption applications because it contains amino and hydroxyl groups in its chemical structure (molecules), resulting in possible interactions of adsorption between chitosan and pollutants (uranium, mercury, rare earth elements (REEs), phenols, etc.). However, adsorption is a very effective, fast, simple, and low-cost process. This review article places emphasis on recent demonstrated research papers (2014–2020) where the chemical modifications of CS are explained briefly (grafting, cross-linking etc.) for the uptake of uranium, mercury, and REEs in synthesized aqueous solutions. Finally, figures and tables from selected synthetic routes of CS are presented and the effects of pH and the best mathematical fitting of isotherm and kinetic equations are discussed. In addition, the adsorption mechanisms are discussed.

Enhancement of Cerium Sorption onto Urea-Functionalized Magnetite Chitosan Microparticles by Sorbent Sulfonation—Application to Ore Leachate

“…Reducing the size of sorbent particles decreases the diffusion path and, consequently, the time required to reach the equilibrium, although this process necessitates the performance a difficult solid/liquid separation at the end of the operative steps. This disadvantage can be minimized through the incorporation of magnetic nanoparticles that facilitate the magnetic separation of the sorbent at the end of the process [ 65 , 66 ]. In some cases, the preparation of magnetic sorbents proceeds through the simultaneous synthesis of magnetite nanoparticles and precipitation of chitosan (first, by mixing the Fe(III) and Fe(II) precursors with chitosan before processing the hydrothermal precipitation at a controlled pH).…”

Recovery of rare earth elements (Nd, Dy) from discarded hard disk magnets using EDTA functionalised chitosan

“…24 Among these, chitosan is a highly promising adsorbent material due to its wide availability and adjustability in its chemical structure. 25 Chitosan, a biopolymer derived from chitin, is a promising adsorbent material for metal ions due to its high surface area, porosity, and adjustable chemical structure. The chelating capacity of chitosan is derived from its molecular structure, which includes amino groups (-NH 2 ).…”

Modified magnetic chitosan materials for heavy metal adsorption: a review

“…Studies on magnetic chitosan adsorption have been summarized by some scholars (see Table 1 ). Briao et al 15 focuses on the regeneration of adsorbents, Shaumbwa et al 16 on the separation of magnetic materials, and Michailidou et al 17 on the adsorption of highly toxic elements such as uranium and mercury. We focus on the adsorption of magnetic chitosan to common polluting metal ions (Cu/Pb/Cr).…”