Recently, calcium sulfite (CaSO3) has been increasingly considered to be as the most potential substitution of PMS/PDS to produce SO4-• for degrading the target organic pollutants due to its less toxic side effects, lower cost and no residues after decontamination. For this direction, herein, we reported carbon nanotubes (CNTs) as an efficient catalyst and nanoreactor in activating CaSO3 for water decontamination. Compared with NaHSO3 and Na2SO3, the result exhibited that the order of tetracycline (TC) removal rate at 30 min as follow: CaSO3 (80.2 %)> Na2SO3 (49.3 %) > NaHSO3 (48.8 %). Because CaSO3 could slowly discharge SO32-, and it could be used as a sustained-release SO32- source, which could solve effectively the quenching issue of SO4•- at the high concentration of SO32-. Control experiments confirmed that the vital roles of electron transfer and dissolved O2 in the formation of SO3•- and SO4•- in CNTs/CaSO3 system, which was also verified by quenching experiments and EPR analysis. More importantly, we found CNTs/CaSO3 system had the excellent potential on the treatment of actual pharmaceutical wastewater, with total organic carbon and chemical oxygen demand dropped by 42% and 70% after treatment, respectively. In addition, germination experiments of wheat seeds had confirmed that the bio-toxicity of TC to wheat seeds was greatly reduced after treatment by CNTs/CaSO3 system.

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