**7. Ion exchangers of functional thiol groups**

The chelating ion exchangers of functional thiol and methylene thiol groups with the com‐ mercial names: Chelite S, Duolite GT-73, Imac GT-73, Duolite GT-74, Purolite S-924, Spheron Thiol 1000 and Tulsion CH-97 are widely applied in sorption and separation of noble metal ions [55, 56, 64-69]. Introducing 8-hydroxchinoline (HOxn) and sodium salicylate groups to the methacrylate polymer matrix generates two new chelating ion exchangers Spheron Oxine 1000 and Spheron Salicyl 1000, respectively, which similar to Spheron Thiol 1000 are applied in the separation of Pd(II) and Cu(II) ions. From the determined ion exchange capacities, the affinity series of Spheron ion exchangers towards Pd(II) ions is as follows: *Spheron Thiol 1000 (0.949 mmol/g) > Spheron Oxine 1000 (0.536 mmol/g) > Spheron Salicyl (0.094 mmol/g)* [68]. Elution of Pd(II) and Cu(II) ions form the ion exchanger Spheron Oxine 1000 was conducted using 0.5 M thiourea solution (pH = 2) and 2 M HCl [70].
