Natural Clay Modified with ZnO/TiO2 to Enhance Pollutant Removal from Water

Raw clays, extracted from Bana, west Cameroon, were modified with semiconductors (TiO2 and ZnO) in order to improve their depollution properties with the addition of photocatalytic properties. Cu2+ ions were also added to the clay by ionic exchange to increase the specific surface area. This insertion of Cu was confirmed by ICP-AES. The presence of TiO2 and ZnO was confirmed by the detection of anatase and wurzite, respectively, using X-ray diffraction. The composite clays showed increased specific surface areas. The adsorption property of the raw clays was evaluated on two pollutants, i.e., fluorescein (FL) and p-nitrophenol (PNP). The experiments showed that the raw clays can adsorb FL but are not efficient for PNP. To demonstrate the photocatalytic property given by the added semiconductors, photocatalytic experiments were performed under UVA light on PNP. These experiments showed degradation up to 90% after 8 h of exposure with the best ZnO-modified clay. The proposed treatment of raw clays seems promising to treat pollutants, especially in developing countries.

Automated summary

This study modified raw clays extracted from Bana, west Cameroon with semiconductors (TiO2 and ZnO) to enhance their photocatalytic and depollution properties. The experiments confirmed the improvement in semiconductor properties and larger specific surface areas of the composite clays. The raw clays showed good adsorption for fluorescein, but were not efficient for p-nitrophenol. Photocatalytic experiments with UVA light demonstrated significant degradation of p-nitrophenol after 8 hours of exposure, particularly with ZnO-modified clay.