The recycling of sulphur in waste and conversion to manganese sulphate: Process optimization, kinetic study, mechanistic insights

Waste sulphur produced in industrial processes is often exposed to the air, and its diffusion and combustion in the environment can produce harmful substances, posing a significant risk to ecological safety and human health. Herein, a novel method for the direct treatment of solid sulphur with manganese dioxide based on a simple sealed reactor is proposed. Significantly, the developed sulphur treatment technology could prepare high purity manganese sulphate at the same time. Under the optimum conditions of the reaction temperature of 187.2°C, reaction time of 21.6 h, sulphuric acid loading of 1.00 mol ∙ L −1 , and manganese dioxide dosage of 4.00 mol ∙ mol‐S −1 derived by the response surface method (RSM), the removal efficiency of sulphur could reach near 100%, and the purity of the manganese sulphate product obtained was more than 98%. Kinetic model fitting analysis and several characterization methods were adopted to confirm that the reaction process between sulphur and manganese dioxide follows the unreacted nuclear model controlled by surface chemical reaction, and the transformation paths of Mn and S elements were proposed. This study provides a novel method for the resource treatment of waste sulphur and the preparation of high purity manganese sulphate.