Visible-light-driven photocatalytic removal of acetaminophen from water using a novel MWCNT-TiO2-SiO2 photocatalysts

The addition of MWCNT reduced the band gap of TiO2 from 3.2 eV to 2.82 eV. Dark adsorption resulted in insignificant changes in APAP concentration. The greatest changes in APAP concentration during Vis irradiation over the tested nanocomposites were observed using CNT10 (Fig. 10B). The highest efficiency was exhibited by the nanocomposite containing 1.72 wt% of MWCNT that enabled 81.6 ± 0.6% removal of APAP from water. Generally, an increase of MWCNT concentration up to 1.72 wt% in the nanocomposites induced APAP removal. The nanocomposites possessing higher MWCNT addition were, however, not so efficient (63.2 ± 2.4% and 62.2 ± 4.2% removal). The enhanced photocatalytic activity of different nanocomposites is observed only in the narrow range. The obtained results confirmed that photogenerated holes and, to a lower extent, O2− and OH radicals played the key role in photocatalytic APAP removal over MWCNT-TiO2-SiO2. The studies using Vibrio fischeri have confirmed that photocatalytic oxidation is an effective method for reducing water toxicity.