Open hollow structured Calotropis gigantea fiber activated persulfate for decomposition of perfluorooctanoic acid at room temperature

Perfluorooctanoic acid (PFOA) is an anthropogenic persistent organic compound that resistant to traditional oxidative decomposition, bringing thus huge pressure to the environment. Here, the open hollow structured Calotropis gigantea fiber (CGF) was developed using a facile pyrolysis and subsequent magnetization method, and the resulting magnetic carbonized fiber (MC-CGF) was applied as an efficient catalyst for PFOA decomposition at room temperature in persulfate-based oxidation process. The experimental results indicated that with the addition of MC-CGF, the removal efficiency of PFOA could reach to 75.76% at 30℃ and pH 2.0. By calculation, the apparent activation energy was reduced from 62.76 kJ/mol to 22.49 kJ/mol, demonstrating that in the presence of MC-CGF, a lower reaction temperature and a shorter time were enough to reach the higher efficiency for PFOA decomposition. Mechanism research showed that during the decomposition process, PFOA underwent a first decarboxylation process and two possible decomposition pathways should also be taken into discussion. Taking pakchoi as the plant model, the process toxicity was finally evaluated, and the changes in chlorophyll content stated that the decomposition process of PFOA by MC-CGF assisted persulfate system was relatively harmless and environmental-friendly.