Thermal decomposition and oxidation of cation exchange resins with and without Na2CO3–K2CO3 salt

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Owing to the capability of trapping sulfur and reducing the formation of sulfur bridges, the addition of carbonate salt is one of the ideal destruction technologies for the treatment of cation exchange resins (CERs). The oxidation processes of CERs with and without Na 2 CO 3 –K 2 CO 3 salt were investigated using TG, FT-IR and XPS. The results of these analyses indicate that in addition to the evaporation process, the oxidation process of CERs can be described as: during the thermal decomposition of the sulfonic acid groups, there are direct destruction of functional groups and the dehydration of functional groups. In addition to the destruction of styrene-divinylbenzene copolymer, the continuous oxidation process includes the direct thermal decomposition of sulfonyl bridges and the formation of sulfur bridges, which decompose at high temperature. The elemental analysis results confirmed that the presence of carbonate salt reduced the formation of sulfur bridges in residue. The SO 2 can be effectively adsorbed by carbonate salt to form sulfate in the salt. Moreover, the content of sulfate ions in waste salt were determined by ICP-MS, which proves that oxidation with Na 2 CO 3 –K 2 CO 3 at 550 °C for 1 h is the optimal oxidation condition to form the sulfate in carbonate salt. • The Na 2 CO 3 –K 2 CO 3 salt can effectively promote the oxidation of resins. • Carbonates can convert the sulfur bridge structure in residue into sulfate. • Four oxidation processes of resin are described by quantifying S content.