The Effect of Air on the Oxidation Decomposition of Cationic Exchange Resins in a Ternary Li2CO3−Na2CO3−K2CO3 Molten‐Salt System

The oxidation decomposition of resin was improved with the addition of air. Most sulfur dioxide gas produced from resin oxidation was absorbed by the molten salt and caused the increase in the sulfur retention ratio. Besides, the relative proportion of thiophene sulfur in residue structure decreased at 720 °C in air atmosphere compared to N₂ atmosphere.

Abstract

The molten-salt oxidation method (MSO) can be applied for disposal of spent cationic exchange resins (CERs) after the treatment of nuclear industry wastewater. In this work, the oxidation decomposition of resins in carbonate molten salt in N₂ and air atmospheres was investigated. The SEM morphology and FTIR spectrograms indicated that the addition of air obviously prompted the oxidation decomposition of the benzene ring, S−O bond and S−C bond in residues and the decomposition efficiency of resins reached 98.69 % at 800 °C. The XPS analysis showed the conversion of sulfur species in residues. The peroxide and superoxide ions in carbonate molten salt prompted the decomposition of thiophene sulfur and resulted in the formation of sulfate. The retention rate of sulfur in spent salt was 84.36 % at 800 °C. This work provided more theoretical guidance for the treatment of resins and technical support for the sustainable development of nuclear industry.

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