Advanced removal of pesticides, herbicides, and pharmaceutical residues from surface water.

This work is interested in studying the removal of 27 harmful pollutants from drinking water in the Rosetta branch of the River Nile by advanced treatment processes (i.e. photo-catalysis under natural conditions and normal pH of surface water). The concentration levels of the selected pesticides (11 compounds) in raw water by the spiking method ranged from 1.57-0.40 µg/L, while the concentration of pharmaceuticals (10 compounds) ranged from 41.56-5.95 µg/L and the herbicides (6 compounds) in the range of 1.89-1.37 µg/L. For this purpose, TiO2-Hombikat/alumina (T/A) was prepared by a two-step method; sonication followed by the hydrothermal method. Cu/TiO2-Hombikat/alumina was prepared hydrothermally (H-Cu/T/Al) and by the wet impregnation method (Ma-Cu/T/Al). The prepared materials were characterized by XRD and SEM. The use of advanced treatment could successfully remove selected pollutants. In the case of pharmaceutical residues, the prepared catalysts showed a powerful efficiency in the complete removal of sulfamethazine, while only (T/A) and (H-Cu/T/Al) showed such an efficiency in the complete removal of diclofenac sodium. On the other hand, lower efficiencies were observed with caffeine (17.99% (T/A) and 24.05% (H-Cu/T/Al)). In the case of pesticides, a high removal of pendimethalin (93.77%) using (H-Cu/T/Al) and 86.03% by using (Mb-Cu/T/Al), whereas lower efficiencies were observed for T/A toward the degradation of aldicarb (15.6%) (l) and H-Cu/T/Al (26.07%). In the case of herbicides, the catalysts showed no more than 57% efficiency in the removal of these pollutants.

Synthesis and electrochemical performance of α-Al2O3 and M-Al2O4 spinel nanocomposites in hybrid quantum dot-sensitized solar cells.

The aim of this study is to describe the performance of the aluminum oxide nanoparticle and metal aluminate spinel nanoparticle as photo-anodes in quantum dot photovoltaic. By using a sol-gel auto combustion method, Al2O3 NPs, CoAl2O4, CuAl2O4, NiAl2O4, and ZnAl2O4 were successfully synthesized. The formation of Al2O3 NPs and MAl2O4 (M=Co, Cu, Ni, Zn) nanocomposite was confirmed by using several characteristics such as XRD, UV-Vis, FTIR, FE-SEM, and EDX spectra. The XRD shows that the CoAl2O4 has a smaller crystallite size (12.37 nm) than CuAl2O4, NiAl2O4, and ZnAl2O4. The formation of a single-phase spinel structure of the calcined samples at 1100 °C was confirmed by FTIR. Our studies showed that the pure Al2O3 NPs have a lower energy gap (1.37 eV) than synthesized MAl2O4 under UV-Vis irradiation. Due to the well separation between the light-generated electrons and the formed holes, the cell containing ZnAl2O4 nanocomposite with CdS QDs has the highest efficiency of 8.22% and the current density of 22.86 mA cm-2, while the cell based on NiAl2O4 as a photoelectrode, six cycles of CdS/ZnS QDs, and P-rGO as a counter electrode achieved the best (PCE) power conversion efficiency of 15.14% and the current density of 28.22 mA cm-2. Electrochemical impedance spectroscopy shows that ZnAl2O4 and NiAl2O4 nanocomposites have the highest life times of the photogenerated electrons (τn) of 11*10-2 and 96*10-3 ms, respectively, and the lowest diffusion rates (Keff) of 9.09 and 10.42 ms-1, respectively.

Sol-Gel and Thermally Evaporated Nanostructured Thin ZnO Films for Photocatalytic Degradation of Trichlorophenol.

In the present work, thermal evaporation and sol-gel coating techniques were applied to fabricate nanostructured thin ZnO films. The phase structure and surface morphology of the obtained films were investigated by X-ray diffractometer (XRD) and scanning electron microscope (SEM), respectively. The topography and 2D profile of the thin ZnO films prepared by both techniques were studied by optical profiler. The results revealed that the thermally evaporated thin film has a comparatively smoother surface of hexagonal wurtzite structure with grain size 12 nm and 51 m(2)/g. On the other hand, sol-gel films exhibited rough surface with a strong preferred orientation of 25 nm grain size and 27 m(2)/g surface area. Following deposition process, the obtained films were applied for the photodegradation of 2,4,6-trichlorophenol (TCP) in water in presence of UV irradiation. The concentrations of TCP and its intermediates produced in the solution during the photodegradation were determined by high performance liquid chromatography (HPLC) at defined irradiation times. Complete decay of TCP and its intermediates was observed after 60 min when the thermal evaporated photocatalyst was applied. However, by operating sol-gel catalyst, the concentration of intermediates initially increased and then remained constant with irradiation time. Although the degradation of TCP followed first-order kinetic for both catalysts, higher photocatalytic activity was exhibited by the thermally evaporated ZnO thin film in comparison with sol-gel one.