Thiosulfate (S2O32-) hosts redox stability in time frame of days, rendering it a candidate ion exchange competitor in anoxic groundwaters during the brief time frames of treatment processes. Indeed, this research determined that the oxyanion thiosulfate (S2O 32-) competed with perchlorate (ClO4 -) for sorption onto activated carbons that had been preloaded with a quaternary ammonium surfactant. Moreover, this research showed that when proper prechlorination oxidized this S2O32- to sulfate (SO42-), this competition was diminished. When rapid small-scale column test employed Redlands, CA, groundwater that contained a native 30 μg/L ClO4-, this exhibited a 6 μg/L ClO4- breakthrough after 33,000 bed volumes (BVs) when processed through bituminous-based granular-activated carbon that had been preloaded with a quaternary ammonium surfactant, namely, 0.24 g/g dicocoalkyldimethylammonium chloride (Arquad 2C-75). When this same water was spiked with 1,000 μg/L S2O32-, 6 μg/L of ClO4- broke through at 17,000 BV. However, when S 2O32- spiked Redlands groundwater was also spiked with 2,500 μg/L chlorine, this reactant stoichiometrically oxidized the S2O32- so as to diminish this competition, such that 6 μg/L ClO4- broke through at 31,000 BV. Similar rapid small-scale column test trends were exhibited when using deionized distilled water that had been spiked with ClO4-, S 2O32-, and chlorine.
All Science Journal Classification (ASJC) codes
- Environmental Chemistry
- Waste Management and Disposal