Studies on the heterogeneous photocatalytic oxidation of 2,6-dinitrophenol in aqueous TiO2 suspension

Photodegradation of Congo red in aqueous solution on ZnO as an alternative catalyst to TiO2

“…• OH + Dye ĺ degradation of the dye (8) The photo corrosion of ZnO is complete at pH lower than 4 [17,18] and ZnO can be photo-oxidized to Zn(II) and oxygen (Eqs. 9 and 10).…”

“…Photocatalytic activity of anionic dyes (mainly sulfonated dyes) such as Congo red reaches a maximum value in lower zero point charge. At pH > zpc, the surface is negatively charged and repels R-SO 3 -ions [18]. Furthermore, dye molecules in acidic or highly acidic pH ranges tend to aggregate and form tautomerism state.…”

Photomineralization of phenol on Al2O3: synergistic photocatalysis by semiconductors

“…Water is adsorbed on the semiconductor, both molecularly and dissociatively [2,3]; hole-trapping by either the surface hydroxyl group or water molecule results in short-lived HO • radicals, which are the primary oxidizing agents [4][5][6][7]. Reports on the photodegradation of phenol are numerous and TiO 2 in different modifications [8][9][10], including metal-doped [8] and dye-sensitized TiO 2 [11], ZrO 2 [12], MoO 3 [10,12], MoS 2 [13], WO 3 [9], WS 2 [14], PW 12 O 40 3- [15], a-Fe 2 O 3 [10,15], CuO [10], GdCoO 3 [16], ZnO [9,10], ZnS [10], CdO [10], CdS [9,10], CdSe/TiO 2 [17], In 2 O 3 /TiO 2 [18], SnO 2 [13], Bi 2 O 3 [10], Sb 2 O 3 [10], and CeO 2 [10], are the semiconductors used as a catalyst. The present results reveal that UV light mineralizes phenol chemisorbed on Al 2 O 3 , an insulator.…”

Photodegradation of chlorophenolic compounds using zinc oxide as photocatalyst: experimental and theoretical studies

“…Semiconductor photocatalysts offer huge potential for elimination of toxic chemicals [2]. The photocatalytic degradation of organic pollutants in water and air, using semiconductors such as TiO 2 and ZnO, have been the focus of research recently due to their unique ability in environmental detoxification [2][3][4][5][6]. The ZnO has a wide bang gap = 3.37 eV, which absorbed over a larger fraction of the solar spectrum than TiO 2 [7,8], thus it has more activity for photocatalytic degradation of organic pollutants.…”