Corrigendum to "Ozonation of indigo enhanced by carboxylated carbon nanotubes: Performance optimization, degradation products, catalytic mechanism and toxicity evaluation" [Water Res. 68 (2014) 316–327]. (1st March 2015) - Qu, Ruijuan; Xu, Bingzhe; Meng, Lingjun; Wang, Liansheng; Wang, Zunyao