**9. Ion exchangers of functional thiosemicarbazide, piperazine and tetrazine groups**

Table 1 presents the characteristic of chosen chelating ion exchangers of thiosemicarbazide, piperazine and tetrazine functional groups widely applied in the concentration and removal of platinum group ions [77–80].


**Table 1.** Examples of the chelating ion exchangers of thiosemicarbazide, piperazine and tetrazine functional groups and their characteristic.
