Waste minimization pretreatment via pyrolysis and oxidative pyroylsis of organic ion exchange resin

Pyrolysis and/or oxidative pyrolysis of organic ion exchange resins and other combustible waste may be effective pretreatment processes before vitrification. To further examine these processes, organic ion exchange resins were pyrolyzed or oxidatively pyrolyzed with the use of a small-scale, commercial TGA. Volatilization of the anionic and cationic resins was observed separately for each resin as a function of temperature for pyrolysis and oxidative pyrolysis conditions. The quantity of remains or residue was found to be dependent on the method employed. Three different methods were examined with the TGA to pretreat the resins: pyrolysis; oxidative pyrolysis; and oxidative pyrolysis of ash remaining after the pyrolysis of resin. The latter two methods were found to provide better volume reduction than the pyrolysis-only process. Between the two types of resins, cationic and anionic, the cationic exchange resin was less volatile. Pyrolysis and oxidative pyrolysis of mixed resin (50% cation and 50% anion by wt.) showed volatilization at the temperatures where volatilization was observed for each of the separate resins. Because of certain limitations of the commercial TGA, tube furnace experiments were performed, generally, to examine the pyrolysis of larger quantities of cationic, anionic, and mixed resin, and to examine off-gas characteristics. The cationic resin-only and anionic resin-only gravimetric results showed good agreement with the smaller-scale TGA results. SEM pictures of the different variants of the resin (cationic, anionic, and mixed) show a different morphology for each. Off-gas data showed the presence of H2S, SO2, CO, and NO during the pyrolysis of cationic resin. CO was observed during the pyrolysis of anionic resin. The mixed resin trials showed the presence of the gases approximately at the temperatures where the gases would evolve if the results of the two different resins (cationic and anionic) were superimposed. However, the amount of hydrogen sulfide relative to the sulfur dioxide was found to increase significantly compared to the results of the cationic resin-only trials.