Freezing-enhanced processing method for organic pollutants by peroxymonosulfate

摘要

The present invention provides a freezing method for accelerating the process of peroxide monosulfuric acid (PMS) mediated organic pollutant decomposition. The degradation of furfuryl alcohol (FFA) in the presence of PMS was significantly accelerated by freezing. The FFA degradation efficiency was 10.4% in 25°C aqueous solution, but 100% degradation of FFA was achieved after 3 hours of reaction with [FFA] = 20 μM and [PMS] = 100 μM concentration in -20°C freezing solution. The accelerated degradation of PMS-mediated FFA in the freezing solution is due to the increased concentration of PMS and FFA at the ice crystal boundary, which increases the collision frequency between PMS and FFA to promote redox transformation. Mapping images of PMS and FFA in frozen samples obtained using confocal Raman microscopy provide clear evidence that PMS and FFA accumulated at the ice crystal boundary after freezing. As a result of the experiment with a sulfate radical scavenger, hydroxy radicals (·OH) and SO 4·- were not generated, and the high pollutant-dependent decomposition efficiency showed that PMS-mediated decomposition in the frozen solution was organic contamination with SO 4·- or ·OH. It suggests that it proceeds not through the reaction of the material (radical mechanism) but through direct electron transfer from organic contaminants to the PMS (non-radical mechanism). The degradation efficiencies of the PMS/freeze system were similar in the pH range of 3-10. In addition, the PMS/freeze system operated efficiently in the temperature range of -10 to -35°C. This result means that in cold regions the PMS/freezing system can be operated without external energy.