Chloroform, as a widely used organic solvent, is persistent and can’t be effectively removed from the environment. Recent developments of persulfate activation with iron nanoparticles have attracted much attention. However, the removal efficiency of chloroform is suppressed because it is poorly reactive with iron-activated persulfate and the iron nanoparticles are easily inactive in real environment. In this study, a new system for the removal of chloroform from water was developed, in which the tannic acid was used to improve the activation of persulfate with Fe/Ni nanoparticles (Fe/Ni). The effects of molar ratio of tannic acid to Fe (mol% tannic acid-Fe), persulfate concentration, initial pH value, reaction temperature, inorganic anions and natural organic matters on chloroform removal were investigated. The tannic acid-Fe/Ni-persulfate system with 1.65 mol% of tannic acid-Fe and 3.2 mM of persulfate presented high removal percentage (86.6%-96.7%) in a wide range of pH (2.9-10.7). The results of electron paramagnetic resonance and radical quenching experiments indicated that sulfate radicals and hydroxyl radicals were primarily responsible for the removal of chloroform. In the presence of tannic acid, the Fe-tannic acid chelation could prevent the precipitation of iron hydroxide on Fe/Ni and therefore preserve their active sites. The tannic acid-Fe/Ni-persulfate system showed excellent removal performance for the recalcitrant chloroform, making it a very promising candidate for practical applications.

Tannic acid promotes the activation of persulfate with Fe/Ni nanoparticles for highly efficient chloroform removal

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