In this paper, Fe₂O₃ and Fe₂O₃-zeolite nanopowders are prepared by chemical precipitation utilizing the rusted iron waste and natural zeolite. In addition to the nanomorphologies; the chemical composition, structural parameters, and optical properties are examined using many techniques. The Fe₂O₃-zeolite photocatalyst showed smaller sizes and higher light absorption in visible light than Fe₂O₃. Both Fe₂O₃ and Fe₂O₃-zeolite are used as photocatalysts for methylene blue (MB) photodegradation under solar light. The effects of the contact time, starting MB concentration, Fe₂O₃-zeolite dose, and pH value on photocatalytic performance are investigated. The full photocatalytic degradation of MB dye (10 mg/L) is achieved using 75 mg of Fe₂O₃-zeolite under visible light after 30 s, which, to the best of our knowledge, is the highest performance yet for Fe₂O₃-based photocatalysts. This photocatalyst has also shown remarkable stability and recyclability. The kinetics and mechanisms of the photocatalytic process are studied. Therefore, the current work can be applied industrially as a cost-effective method for eliminating the harmful MB dye from wastewater and recycling the rusted iron wires.

A laser Thomson scattering technique has been used to directly measure the electron density (n _e) and electron temperature (T _e) profiles of a striated plasma in a plasma display panel (PDP)-like discharge. A modulation in n _e was observed only on the anode side of an electrode substrate; this corresponds to a feature similar to that of the emission images obtained using an intensified charge-coupled device (ICCD) camera. Also, a modulation in T _e was observed and it was found to be out of phase from the modulation in n _e.

Undoped and nitrogen (N)^_doped Cu₂O/CuO thin films were deposited via reactive DC magnetron sputtering. The deposition was carried out by sputtering the Cu targets under various Ar/N₂/O₂ gas flow ratios. The structural, optical, wettability, and photocatalytic performance of the deposited films were investigated. A simple cubic Cu₂O crystallographic phase is observed for the undoped film, whereas mixed cubic Cu₂O and monoclinic CuO phases (Cu₂O/CuO) are observed for the N^_doped films. EDAX revealed that as the N₂ flow rate increased the amount of nitrogen incorporated into the film increased. The transmittance and reflectance are affected by the incorporation of nitrogen into the films. The transmittance values decreased with increasing N₂ flow rate, whereas the reflectance values increased. Both the refractive index and extinction coefficient almost increased with increasing N₂ flow rate. A noticeable optical band gap narrowing from 2.55 eV to 2.39 eV was detected upon increasing the N₂ flow from 0.0 to 190 sccm. The photoluminescence spectrum of the undoped sample contains five distinct bands at 518, 612, 654, 714 and 825 nm. These five maxima are attributed to the radiative decay of bound and free excitons, and oxygen vacancies (V_O) After nitrogen incorporation, the photoluminescence intensity decreases and then increases again with increasing N₂ flow rate. A reduction in the water contact angle was observed with increasing N₂ flow rate. Upon Vis-light illumination, the N^_doped Cu₂O/CuO films reached superhydrophilicity faster than the undoped film did. The photocatalytic performance of the deposited Cu₂O/CuO films was strongly enhanced with a small amount of N doping. The deposited films are promising for self-cleaning and photocatalytic degradation of organic wastes.

More suitable wastewater treatment schemes need to be developed to get rid of harmful dyes and pigments before they are discharged, primarily from apparel and textile factories, into water bodies. Silver nanoparticles (Ag-NPs) are very effective, reductive nanocatalysts that can degrade many organic dyes. In this study, Ag-NPs are stabilized and capped with bioactive compounds such as Galaxaura elongata, Turbinaria ornata, and Enteromorpha flexuosa from marine macroalgae extracts to produce Ag[GE], Ag[TE], and Ag[EE] NPs. The reduction of Ag ions and the production of Ag[GE], Ag[TE], and Ag[EE] NPs have been substantiated by UV–Vis spectroscopy, SEM, EDX, and XRD tests. The NPs are sphere and crystalline shaped in nature with dimensions ranging from 20 to 25 nm. The biosynthesized Ag[GE], Ag[TE], Ag[EE] NPs were applied to photodegrade hazardous pigments such as methylene blue, Congo red, safranine O, and crystal violet under sunlight irradiation. In addition to the stability analysis, various experimental parameters, including dye concentration, exposure period, photocatalyst dose, and temperature, were optimized to achieve 100% photodegradation of the dyes. Moreover, the thermodynamic and kinetic parameters were calculated and the impact of scavengers on the photocatalytic mechanism was also investigated.

In the present work, a pulsed pin-to-plate corona reactor has been used for phenol removal from water. The main advantage of the present reactor is the presence of electrospraying of water drops at the tip of the discharge pin simultaneously with corona streamer. Electrospraying increases the treated surface area and therefore increases the efficiency of the water treatment. Also, the microdroplets of the sprayed water pass through the different regions of the discharge streamer and hence are in contact with the different plasma species which enhances the treatment process. The physical and chemical reactions of the plasma species affecting the phenol treatment have been discussed. Effects of the applied voltage, the running number of re-treatments, the phenol concentration, and the type of the working gas on the treatment process have been studied. At optimum conditions of the reactor, a percentage removal of phenol of 99.5% has been achieved with an efficiency of 2.5 g/kWh.