Abstract :
[en] In the two first parts of this study, raw clays extracted from Bana, in western Cameroon, were modified with semiconductors (TiO2 and ZnO) to improve their pollution control properties by adding photocatalytic properties. Also Cu²⁺, Na+ and Zn2+ ions were added to the clay by ion exchange to increase the specific surface area, and to modify the charge of the clay surface. The results obtained from X-ray diffraction show that the clay belonged to the smectite family and was composed of different crystalline phases. Furthermore, the presence of TiO2 and ZnO was confirmed by the detection of anatase and wurtzite, respectively. Furthermore, the composite clays showed increased specific surface areas. Finally, the pollutant removal properties of the samples were evaluated using different model pollutants: fluorescein (FL), p-nitrophenol (PNP), malachite green (MG) and diamond bright violet (DBV). It was demonstrated the possibility of obtaining highly effective hybrid materials for the removal of pollutants from water using inexpensive natural clay modified with a small amount of photocatalytic material (approximately 30% by weight of TiO2 or ZnO).
The third step consisted of modifying the clay material with two silanes, tetramethoxysilane (TMOS) and [3-(2-aminoethyl)aminopropyl]trimethoxysilane (EDAS), to increase its adsorption properties. The modified clay is intended for use as an effective adsorbent for the removal of organic pollutants from water. Three Clay/TMOS samples and two Clay/EDAS samples with different [silane]/[clay] ratios were produced and characterized. Their adsorption properties were evaluated on three model organic pollutants (i.e., FL, MG, and DBV). The two types of clays modified with TMOS and TEOS, respectively, exhibit two different adsorption behaviors for the three pollutants.
In the final part of this study, the growing presence of pharmaceuticals in wastewater, such as ibuprofen, which raises serious environmental and public health concerns, was demonstrated. In this study, some photocatalytic ZnO and TiO2-doped natural Cameroonian clays were used to ensure effective degradation of ibuprofen and bacterial inhibition under UV light (365 nm). Characterization confirmed the successful dispersion of semiconductors on the clay matrix. Under UV irradiation, the composites achieved significant degradation efficiencies, with mineralization monitored by total organic carbon (TOC), and antibacterial tests revealed notable inhibition against Shigella spp., supporting the dual functionality of the materials.
