# Metachrylate-Based Polymeric Sorbents for Recovery of Metals from Aqueous Solutions
## 7 Adsorption on Amino-Functionalized Glycidyl Methacrylate-Based Polymers
On the other hand, at pH 5.5, the metal sorption capacities of PGME-en decreased in the order: Cu(II) \(>\) Co(II) \(>\) Pt(IV) \(\approx\) Ni(II) \(>\) Pb(II). Reusability was also proven since the regeneration with 2 M H\({}_{2}\)SO\({}_{4}\) of the Cu(II), Ni(II), and Pt(II) loaded PGME-en showed that copolymer can be reused in several sorption/desorption cycles. The sorption ability of macroporous PGME-en towards rhodium, gold, and platinum (Rh(III), Au(III), and Pt(IV)) [61] ions were also examined. A faster Rh(III) uptake than those of Au(III) and Pt(IV) was observed. After 5 min of sorption, approx. 90% Rh(III), 57% of Pt(IV), and 46% of Au(III) had been sorbed. These different sorption rates of Rh(III), Au(III), and Pt(IV) enabled PGME-en application for the selective separation of platinum metals. Due to strong coordination with the modified copolymer, Rh(III) desorption was very difficult and incomplete, even with strong acids (such as HCl and H\({}_{2}\)SO\({}_{4}\)). It was shown by the same research group that PGME-en can sorb 5-8 times more Pt(IV) than Cu(II) and Ni(II) ions from single-component solutions and 5 times more Pt(IV) than Cu(II) from their mixed chloride solutions [134]. The sorption performances of macroporous PGME with attached diethylene triamine, PGME-eta, for Cu(II), Cd(II), and Pb(II) sorption were determined in batch static experiments at room temperature [118]. The sorption half time was approx. 5 min for all metal ions. High capacities were observed, i.e., PGME-eta after 30 min reached approx. 90% and after 180 min, 95% of maximum capacity. It was shown that PSO kinetic model best fitted the Cu(II), Cd(II), and Pb(II) sorption, suggesting that the sorption rate is controlled by both sorbent capacity and concentration, with the influence of intraparticle diffusion. [PERSON] et al. used glycidyl methacrylate-based copolymer with acetamide groups as Hg(II) sorbents [135]. The Hg(II) ions sorption capacity was approx. 2.2 mmol/g in nonbuffered solutions. On the other hand, the adsorption capacities of sorbent for Cd(II), Pb(II), Zn(II), and Fe(III) were relatively low (0.2-0.8 mmol/g). It was shown that Hg(II) ions could be regenerated by repeated treatment with hot acetic acid without hydrolysis of the amide groups, up to 2.0 mmol/g, i.e., 86% of the capacity of fresh polymer. [PERSON] et al. reported Cu(II) and Pb(II) sorption performances of poly(glycidyl methacrylate-\(\omega\)-divinylbenzene) functionalized by ethylene diamine [136]. The results showed that metal-solvent interaction proceeds via surface and diffusion mechanisms. The most suitable pH value for metal sorption was 5.8, while maximum adsorption capacities for Cu(II) and Pb(II) were 1.24 and 0.32 mmol/g, respectively. Regeneration efficiency of 97% was achieved in 10 sorption/desorption cycles with 0.5 HNO\({}_{3}\). [PERSON] et al. tested the triethylene tetra amine-functionalized poly (glycidyl methacrylate-\(\omega\)-ethylene glycol dimethacrylate) as sorbents for Cu(II), Zn(II), Co(II), and Ni(II) ions sorption from seawater [137]. [PERSON] et al. investigated the influence of the porosity parameters, particle size, and type of the ligand on the uptake of heavy metals on macroporous amino-functionalized PGME [133]. Sorption capacities and rates of PGME-en, PGME-data, and PGME-teta for Cu(II) ions were determined. In addition, the selectivity of PGME-data and PGME-teta towards individual metal ions under competitive conditions was investigated as a function of pH and particle size. The Cu(II) sorption was rapid, i.e., the sorption half time for PGME-data and PGME-teta, was approximately 3 min. In addition, the high selectivity of PGME-data for Cu(II) over Cd(II) of 3:1 and for Cu(II) over Ni(II) and Co(II) of 6:1 was observed. The decrease in particle size of PGME-teta resulted in the increase of sorption capacities for all metal ions. [PERSON] et al. published studies on the theoretical modeling of metal ions sorption [124; 125; 138].