Highly Efficient Photocatalyst Fabricated from the Chemical Recycling of Iron Waste and Natural Zeolite for Super Dye Degradation

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

Measurement of Electron Density and Electron Temperature in Decaying Arcs Containing Decomposed Gas from Polymer

Electron density (ne) and electron temperature (Te) in arc discharges generated in the atmospheric air were measured using the laser Thomson scattering (LTS) technique. The arcs were generated using tungsten electrodes with a gap length of 2 mm. At the tip of the cathode electrode, a polymer material-polyoxymethylene (POM) or polytetrafluoroethylene (PTFE)-was inserted to generate the arcs containing the decomposed gas from polymer. LTS results showed that n_e in the arcs varied with the polymer material used. In particular, with POM, the decay speed of n_e was much higher than that with PTFE. The LTS results are qualitatively consistent with the results of previous numerical studies, which indicate that a POM ablation gas can decay the arc conductance more effectively than a PTFE ablation gas

Measurement of Electron Density and Electron Temperature in Decaying Arcs Containing Decomposed Gas from Polymer

Electron density (ne) and electron temperature (Te) in arc discharges generated in the atmospheric air were measured using the laser Thomson scattering (LTS) technique. The arcs were generated using tungsten electrodes with a gap length of 2 mm. At the tip of the cathode electrode, a polymer material-polyoxymethylene (POM) or polytetrafluoroethylene (PTFE)-was inserted to generate the arcs containing the decomposed gas from polymer. LTS results showed that n_e in the arcs varied with the polymer material used. In particular, with POM, the decay speed of n_e was much higher than that with PTFE. The LTS results are qualitatively consistent with the results of previous numerical studies, which indicate that a POM ablation gas can decay the arc conductance more effectively than a PTFE ablation gas

Correlation of acetylene plasma discharge environment and the optical and electronic properties of the hydrogenated amorphous carbon films

Thin films from polymeric and graphitic hydrogenated amorphous carbon (a-C:H) were deposited over a glass substrate from acetylene (C2H2) plasma by using a conventional plasma enhanced chemical vapor deposition (PECVD). Radio frequency capacitively coupled plasma (RF CCP) source operating at a frequency of 13.56 MHz was used for generation of the discharge. Optical emission spectroscopy (OES) results showed strong optical emissions from diacetylene ion C4H2+ at a wavelength of 506 nm. The energy dispersive X-ray (EDS) measurements illustrated that the carbon content in the deposited films increased with increasing of power. The Raman and IR results demonstrated that the films deposited at low bias voltages 340 V are so called polymeric a-C:H with high sp3 fraction and high hydrogen content, while the films deposited at high bias voltages 877 V are so called graphitic a-C:H with low sp3 fraction and low hydrogen content. Quantitative information were obtained from fitting the high asymmetrical vibrational modes of Raman and IR spectra by using Fano model expression together with Lorentzian function. The results presented here point out that there is a relation between the intensity of C4H2+ ion emissions and the deposited films properties

Electrical and Optical Characterization of Acetylene RF CCP for Synthesis of Different Forms of Hydrogenated Amorphous Carbon Films

We present an electrical and spectroscopic characterization of Acetylene plasma used for deposition of different forms of hydrogenated amorphous carbon (a-C:H) films at different discharge powers. Asymmetric radio frequency capacitively coupled plasma source driven by 13.56Â MHz used for generation of the discharge. Fast Fourier transformation of the experimentally measured discharge current waveforms shows several harmonics of the driving frequency, the number and amplitude of these harmonics depends on the experimental conditions. The plasma series resonance (PSR) oscillations generated such harmonics leading to an enhancement of ionization process. Optical emission spectroscopy results showed strong emissions intensities from C4H2+ which varied with both power and pressure, the presence of these emissions attributed to the PSR effect. The formation and transformation of the films from polymeric a-C:H to graphitic a-C:H at different discharge powers was confirmed by Raman, FTIR and optical absorption spectroscopy. For the first time we constructed a ternary phase diagram of the a-C:H films based on the relative intensity ratio of I(C4H2+)/I(CH) to provide quantitative information about the types of the deposited films. We pointed out that the C4H2+ ionic species play the major role in the films formation and transformation process

Photocatalytic Activity of Revolutionary <i>Galaxaura elongata, Turbinaria ornata,</i> and <i>Enteromorpha flexuosa</i>’s Bio-Capped Silver Nanoparticles for Industrial Wastewater Treatment

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

Development of Thomson Scattering Diagnostics for Cathode-Directed Streamer Discharges in Helium

Laser Thomson scattering diagnostics has been developed for the study of the streamer moving toward the cathode in helium near atmospheric pressure. In order to avoid laser perturbation and obtain sufficient intensity of the Thomson scattering signal, two cylindrical lenses were used to optimize the spot size of a probing laser at a focusing point. At a position of 2 mm from the anode (needle electrode), the electron density and electron temperature were successfully measured to be ~ 10^18 m^-3 and ~ 2 eV, respectively, in the initial stage of the primary streamer