# Metachrylate-Based Polymeric Sorbents for Recovery of Metals from Aqueous Solutions
## 7 Adsorption on Amino-Functionalized Glycidyl Methacrylate-Based Polymers  
GMA based macroporous copolymers crosslinked with ethylene glycol dimethacrylate (EGDMA), PGME, and trimethyl trimethyllpropane trimethacrylate (TMPTMA), PGMT, in the shape of regular beads are very interesting due to the ability of the epoxy group to react with nucleophiles, such as amines, thiols, azide, carboxylic acids, etc. (Scheme 1) [121, 122, 68, 111, 123]. This type of copolymers can be synthesized by suspension copolymerization in the presence of a pore-forming agent (inert component, porogen), having a permanent well-developed porous structure even in the dry state, and macroopes with diameters larger than 50 nm [123]. Two different approaches can be used in order to attach ligands. The first one is a copolymerization of a suitable monomer already carrying the required functional group, and the second one or by post-polymerization functionalization, i.e., to perform an additional reaction in order to introduce selective chelating groups. The latter method is more practical and efficient since it could be assumed that all the groups are accessible and reactive. The separation of metal ions on macroporous amino-functionalized GMA copolymers is determined by the sorption parameters (pH, presence of other ions which compete for the active sites), structural properties of the chelating copolymers (particle size, porosity, specific surface area), ligand structure as well as kinetic and thermodynamic stability of the formed metal complexes with the chemically bonded amine ligands [61]. Amino-functionalized GMA based copolymers were proven to be adaptable sorbents for removal of precious [61] and heavy metals [124, 88, 125, 126], technetium-99 [127, 126], as well as chromium [89, 128, 129], molybdenum and rhenium [111, 130], and vanadium [104]. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Adsorbents** & **Metals \({}^{\star}\)** & **pH** & **Concentration** & **Adsorption Capacity** & **Reference** \\ \hline Magnetic-poly(glycidyl & & & & & \\ methacrylate-co-divinylbenzene)-tetraethylenepentamine & U(IV) & 4.5 & 0.525 mM & 1.68 mmol/g & [116] \\ \hline Polyethylenimine/poly(glycidyl methacrylate) & Cr(VI) & 2 & 25–500 mg/L & 492.61 mg/g & [117] \\ magnetic microspheres & & & & & \\ \hline Poly(glycidyl Methacrylate-co-ethylene glycol & Pb(II) & 2 & & & \\ dimethacrylate)-diethylenetriamine & Cut(II) & 4 & 0.05 mol/L & 164 mg/g & \\  & & & & 120 mg/g & [118] \\  & & & & 152 mg/g & \\ \hline Magnetic-poly(glycidyl methacrylate) & Hg(II) & - & 5–2500 mg/L & 543 mg/g & [119] \\ \hline Magnetic-poly(methyl & Co(II) & & & & \\ methacrylate-co-maleic anhydride) & Zn(II) & 6 & 20–100 mg/L & 90.09 mg/g & \\  & & & & 90.91 mg/g & \\  & & & & 109.89 mg/g & \\  & & & & 111.11 mg/g & \\ \hline \hline \end{tabular}  
* Cu-Copper, Hg-Mercury, Cd-Cadmium, Co-Cobalt, Pb-Lead, Cr-Chromium, Fe-Iron, Ag-Silver, Zn-Zinc, Mn-Manganese, Pt-Platinum, Mo-Molybdenum, Au-Gold, Ni-Nickel, Th-Thorium, V-Vanadium, U-Uranium, As-Arsenic, Se-Selenium, Y-Yttrium, La-Lanthanum, Gd-Gadolinium, Tb-Terbium, Pr-Praseodymium, Sc-Scandium.  
\end{table} 
Table 3: _Cont._[PERSON] et al. investigated sorption performances of amino-functionalized PGME towards heavy metals and precious metals [118; 124; 128; 131; 132; 133]. Macroporous crosslinked copolymer of glycolidyl methacrylate and ethylene glycol dimethacrylate with different porosity parameters functionalized with ethylenediamine, PGME-en, towards copper, iron, manganese, cadmium, zinc, lead, chromium, and platinum (Cu(II), Fe(II), Mn(II), Cd(II), Zn(II), Pb(II), Cr(III), and Pt(IV)) ions were studied [88]. It was observed that the sorption rate of PGME-en for Cu(II) ions determined under non-competitive conditions was relatively rapid, i.e., the maximum capacity was reached within 30 min. In addition, strong pH dependence of PGME-en selectivity was observed. Namely, a considerably higher sorption capacity for Pt(IV) in comparison to Cu(II), Co(II), Ni(II), and Pb(II) ions at pH 2.1 was established.