Peganum Harmala plant as an adsorbent for the removal of Copper(II) ions from water

Batch removal of Cu(II) from water by powdered seeds of Peganum Harmala has been investigated in this research. The Peganum Harmala seeds were collected after which they have been beaten slowly, separated and then cleaned using a sieve. The prepared sorption is characterized by FT-IR. Batch adsorption studies have been undertaken in 100 ml Erlenmeyer flasks, inside an incubator container. The main process parameters that are considered are pH, contact time, Cu(II) concentration, the Adsorbent dose effect and reaction temperature effect. Cu(II) is measured at a wavelength of 620 nm, using a UV-vis spectrophotometer. The result evidence that the maximum removal of Cu(II) is observed at pH 6.2, with the pH over 6.2 result to participate the copper hydroxide. Clearly, the uptake process of the Cu(II) ion occurres very swiftly from the outset of the experiments during the first 15 min, after which there is a low decrease until 40 min, when maximum adsorption of Cu(II) ion onto Peganum Harmala is observed. An increased Cu(II) ions removal percentage occurres with increasing dose of adsorbents, increasing from 0.2 to 0.6 g followed by an increased percentage removal from 63.50% to 66.02%. Subsequently, the removal of Cu(II) ions decline, with an increased dose to 1g. Langmuir adsorption isotherm is more appropriate than the Freundlich adsorption isotherm, while the pseudo second-order reaction model is suitable for adsorption of the Copper ion onto the active centers of the Peganum Harmala surface compared with the pseudo first-order model

Peganum Harmala plant as an adsorbent for the removal of Copper(II) ions from water

163-171Batch removal of Cu(II) from water by powdered seeds of Peganum Harmala has been investigated in this research. The Peganum Harmala seeds were collected after which they have been beaten slowly, separated and then cleaned using a sieve. The prepared sorption is characterized by FT-IR. Batch adsorption studies have been undertaken in 100 ml Erlenmeyer flasks, inside an incubator container. The main process parameters that are considered are pH, contact time, Cu(II) concentration, the Adsorbent dose effect and reaction temperature effect. Cu(II) is measured at a wavelength of 620 nm, using a UV-vis spectrophotometer. The result evidence that the maximum removal of Cu(II) is observed at pH 6.2, with the pH over 6.2 result to participate the copper hydroxide. Clearly, the uptake process of the Cu(II) ion occurres very swiftly from the outset of the experiments during the first 15 min, after which there is a low decrease until 40 min, when maximum adsorption of Cu(II) ion onto Peganum Harmala is observed. An increased Cu(II) ions removal percentage occurres with increasing dose of adsorbents, increasing from 0.2 to 0.6 g followed by an increased percentage removal from 63.50% to 66.02%. Subsequently, the removal of Cu(II) ions decline, with an increased dose to 1g. Langmuir adsorption isotherm is more appropriate than the Freundlich adsorption isotherm, while the pseudo second-order reaction model is suitable for adsorption of the Copper ion onto the active centers of the Peganum Harmala surface compared with the pseudo first-order model

Microwave Assisted Preparation of Barium Doped Titania (Ba/TiO2) as Photoanode in Dye Sensitized Solar Cells

Pure TiO2 and barium (0.5 wt%) doped TiO2 (Ba/TiO2) nanostructures have been synthesized via facile microwave irradiation method. The pure anatase phase of synthesized photoactive material was confirmed by X-ray diffraction. Ba doping in the TiO2 host structure influenced the optical band gap as confirmed by UV-visible spectroscopy. The optical band gap increased from 3.21 eV for the TiO2 to 3.26 eV for Ba/TiO2. Morphological analysis of synthesized TiO2 and Ba/TiO2 was conducted using scanning electron microscopy. Energy dispersive X-ray spectroscopy confirmed the formation of Ba/TiO2 and no impurities were observed. Electrochemical impedance spectroscopy showed that the charge transfer resistance increased for Ba/TiO2, which reduced dark current creation in a dye-sensitized solar cell. The highest power conversion efficiency (3.24%) was achieved for Ba/TiO2 photoanode compared to 2.1% for a pure TiO2 photoanode-based device

Synthesis, Characterization and Photodegradation Studies of Copper Oxide–Graphene Nanocomposites

In this work, a simple hydrothermal method was employed to prepare a pristine sample of copper oxide (CuO) and three samples of copper oxide–graphene nanocomposites (CuO-xG) with x = 2.5, 5, and 10 mg of graphene. The synthesized samples were characterized using X-ray powder diffractometry (XRD), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), Fourier-transform infrared spectroscopy (FTIR) and ultraviolet–visible (UV-Vis) spectroscopy. The XRD patterns of CuO-xG nanocomposites exhibited the diffraction peaks related to the crystal planes of monoclinic CuO and hexagonal graphite. The surface morphology of the prepared samples was investigated using FESEM images. EDX analysis was used to investigate the chemical composition of the synthesized samples. FTIR spectroscopy identified the vibrational modes of the covalent bonds present in the samples. The allowed direct optical bandgap energy was calculated for all prepared samples using UV-Vis absorption spectra. The small bandgap of CuO-xG nanocomposites indicates their potential use as an effective photocatalyst in the presence of visible light. Photocatalytic activity of the samples was explored for the degradation of methylene blue (MB) dye contaminant under visible light irradiation. The results showed that the CuO-5G sample has the highest photodegradation efficiency (~56%)

Facile Synthesis of Low-Cost Copper-Silver and Cobalt-Silver Alloy Nanoparticles on Reduced Graphene Oxide as Efficient Electrocatalysts for Oxygen Reduction Reaction in Alkaline Media

Copper-silver and cobalt-silver alloy nanoparticles deposited on reduced graphene oxide (CuAg/rGO and CoAg/rGO) were synthesized and examined as electrocatalysts for oxygen reduction reaction (ORR) and hydrogen peroxide reduction reaction (HPRR) in alkaline media. Characterization of the prepared samples was done by transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray diffraction analysis (XRD), and scanning electron microscopy with integrated energy-dispersive X-ray spectroscopy (SEM-EDS). CuAg/rGO and CoAg/rGO nanoparticles diameter ranged from 0.4 to 9.2 nm. The Ag loading was ca. 40 wt.% for both electrocatalysts, with that for Cu and Co being 35 and 17 wt.%, respectively. CoAg/rGO electrocatalyst showed a Tafel slope of 109 mV dec−1, significantly lower than that for CuAg/rGO (184 mV dec−1), suggesting faster ORR kinetics. Additionally, a higher diffusion current density was obtained for CoAg/rGO (−2.63 mA cm−2) than for CuAg/rGO (−1.74 mA cm−2). The average value of the number of electrons transferred during ORR was 2.8 for CuAg/rGO and 3.3 for CoAg/rGO electrocatalyst, further confirming the higher ORR activity of the latter. On the other hand, CuAg/rGO showed higher peak current densities (−3.96 mA cm−2) for HPRR compared to those recorded for CoAg/rGO electrocatalyst (−1.96 mA cm−2)

Efficient methane dry reforming process with low nickel loading for greenhouse gas mitigation

In this study, a series of nickels supported on gamma alumina with a metal dosage ranging from 0.5 to 3 wt.% were prepared and employed as the catalysts. The effect of nickel dosage on material properties, reaction performance, and catalyst deactivation was investigated. At a low dosage, the nickel-free having low metal-support interaction contributed significantly to the total active site. The basicity of the material was enhanced along with the increase in nickel loading. The presence of active metal showed a great impact at the beginning leading to big improvements in feedstock conversion. However, beyond a nickel dosage of 2 wt.%, further additions did not noticeably influence the reaction performance. Regarding catalyst deactivation, different carbon species were observed on catalyst surface, depending on the nickel dosage. Catalysts with less than 2 wt.% nickel exhibited amorphous carbon as the dominant morphology on the spent catalyst. In contrast, catalysts with 2Ni/Al2O3 and 3Ni/Al2O3 compositions showed graphitic carbon as the main side product. These findings provide insights into the relationship between nickel dosage, catalyst properties, and catalytic performance in methane dry reforming. By understanding the effects of nickel loading on material properties and reaction behavior, researchers can optimize catalyst design and develop more efficient and stable catalysts for sustainable syngas production

Carbon dioxide reforming of methane over modified iron-cobalt alumina catalyst : Role of promoter

Cobalt-based catalysts are widely employed in methane dry reforming but tend to deactivate quickly due to coke deposits and metal sintering. To enhance the performance, iron, a cost-effective promoter, is added, improving cobalt's metal dispersibility, reducibility, and basicity on the support. This addition accelerates carbon gasification, effectively inhibiting coke deposition. Methods: A series of iron-doped cobalt alumina MFe-5Co/Al2O3 (M= 0, 0.4, 0.8, 1, 2 wt.%) were prepared via simple incipient-wetness impregnation. The catalysts were thoroughly characterized via modern techniques including BET, XRD, H2-TPR, CO2-TPD. Significant findings: The addition of iron had a minimal impact on the properties of γ-Al2O3, but it significantly affected the dispersibility of cobalt. At an optimal dosage of 0.8 wt.%, there was a notable decrease of 29.44% in Co3O4 particle size. However, excessive iron loading induced agglomeration of Co3O4, which was reversible. The presence of iron also resulted in a decrease in the reduction temperature of Co3O4. The material's basicity was primarily influenced by the loading of iron, reaching its highest value of 705.7 μmol CO2 g−1 in the 2Fe-5Co/Al2O3. The correlation between catalytic activity and the physicochemical properties of the material was established. The 0.8Fe-5Co/Al2O3 sample exhibited excellent performance due to the favorable dispersibility of cobalt, its reducibility, and its affordable basicity

High throughput optimisation of functional nanomaterials and composite structures for resistive switching memory

The Semiconductor industry is investigating high speed, low power consumption, high-density memory devices that can retain their information without power supply. Resistive Random Access Memory (ReRAM) is one of the most attractive candidates as an alternative to conventional flash memory devices due to of its simple metal-insulator-metal (MIM) structures. A compositional gradient of thin film materials produced by the simultaneous combination of elements provides a powerful tool for the combinatorial synthesis of materials. It was applied here to control the composition, structure and morphology of materials in composite devices of ReRAM. This allows the systematic high throughput screening of the intrinsic properties of the materials, as well as the high throughput optimisations of composite thin films that mimic memory device structures. Therefore, the focus of this project is to develop a novel capacitor for ReRAM application. We present here details of the preparation technique and the screening methodologies of this approach by applying the synthesis to various phases of titania, for which there is an extensive literature, as a prelude to the screening of more complex systems. Inert Pt electrodes and active Cu electrodes were deposited on TiO2 as top electrodes using different mask sizes (50 micron and 250 micron). The bottom electrode is Si/ SiO2/ TiO2/ Pt (SSTOP) was constant throughout this project. TiO2 was prepared using evaporative physical vapour deposition (PVD) with a variation of thickness between 10 nm and 300 nm on SSTOP. The synthetic conditions were chosen to produce TiO2 oxygen stoichiometric and sub-stoichiometric amorphous, anatase and rutile materials. The oxides have been fully characterised by X-Ray Diffraction (XRD), X-ray Photo electron Spectroscopy (XPS), Raman Spectroscopy, Four Point Probe (4pp) and Atomic Force Microscopy (AFM). The electrical screening was carried out on capacitor-like structures produced using 250 micron diameter top electrodes deposited using a 14 x 14 array contact mask. Current-Voltage (I-V) measurements were conducted employing a variety of current compliances (IC). The typical I-V switching of the unipolar mode (both state in one polarity) was achieved on all titania phases, whereas the bipolar mode (each state in different polarity) was achieved only on the amorphous phase. The resistance differences between High Resistance State (HRS) and Low Resistance State (LRS) were clearly identified in each system. It was observed that for all the devices investigated, a lower forming field was required on the thicker layer of the active switching layers. Devices with copper electrodes, and composite devices with sub-stoichiometric titania adjacent to the stoichiometric titania could be formed at lower voltages and electric fields. The results obtained here confirm the feasibility of the high-throughput approach to optimise functional nanomaterials and composite device structures for resistive switching memory application

THE EFFECTS OF SIZE DISTRIBUTION OF GOLD NANOPARTICLES ON NANOSPRINGS FORMATION AND PROCESS EFFICIENCY

In this study, Gold nanoparticles were synthesized by reduction reaction method between chloroauric acid (HAuCl4) and sodium citrate (Na3 C6 H5 O7). These two agents, gold chloride concentration and sodium citrate concentration were changed while the other experimental parameters such as temperature and mixing rate were kept at the same level which effects on particle size and size distribution. The size and the shape of gold particles can be characterized by using scanning electron microscopy (SEM). The particle sizes can be produced in a range of 0.99 to 5.3 μm, and these particles have a spherical shape. In addition, the UV-visible spectroscopy was used in this study to investigate the efficiency of the absorbance of light at various diameters of gold nanoparticles. Also, the vapor liquid solid method was utilized to explore the range of sizes that most efficiently produces nanosprings.masters, M.S., Physics -- University of Idaho - College of Graduate Studies, 2017-1