Removal of 4-chlorophenol from wastewater: Preparation, characterization and photocatalytic activity of alkaline earth oxide doped TiO2

Alkaline earth oxide (MgO, CaO, SrO) doped TiO2 catalysts prepared by impregnation method were successfully used in the photocatalytic degradation of 4-chlorophenol (4-CP) under UV irradiation. The materials were characterized by XRD, BET, FT-IR, DRS, PL, SEM and TEM techniques. Alkaline earth metal oxides resulted in an enhanced efficiency of the TiO2 photocatalyst. The 10 wt% MgO TiO2 showed the highest percentage of 4-CP degradation (100%) and highest reaction rate (0.82 mg L−1 min−1) in 1 h. It was also found that the catalytic activity of 10MgO-TiO2 was found to be higher than nano TiO2 and P-25 photocatalyst. The photocatalytic performances are in the orders of: 10MgO/TiO2 > 10CaO/TiO2 > 10SrO/TiO2. Alkaline earth oxide effectively decreases the band gap of the TiO2. The enhanced adsorption of 4-CP over the catalyst surface and decrease in particle size as a result of Mg2+ loading is suggested to be the cause for higher activity of the catalyst. The profound effect of alkaline earth oxide doped TiO2 for 4-chlorophenol is generally considered due to the entry of Mg2+ into the lattice of nano TiO2 and high dispersion.

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► The addition of alkaline earth oxide effects on the photocatalytic degradation reaction.
► The incipient wetness impregnation for photocatalysis.
► The entry of Mg2+ into the lattice of nano TiO2 for enhancing of the activity.