Band 236, Heft 10

The protection of Egyptian reinforcing concrete infrastructures from corrosion is a pressing and critical task for construction engineering and industry, particularly in coastal locations. The primary aim of this case study is to integrate the advantages of both sacrificial anode cathodic protection (SACP) and impressed current cathodic protection (ICCP) in a single cathodic protection (CP) system and to use the new system in Alamein New Place near the Mediterranean sea (Egypt). The results showed that the new cathodic protection system is running very well to protect the concrete iron bars from corrosion. With the passage of time, the protective system’s efficiency and stability improve. During 30 days, the zinc anode’s potentials remain much more negative, indicating that the zinc anode can retain strong electrochemical activity for an extended length of time. The application of the CP method decreases the corrosion rate of rebar steel in concrete samples over time, according to electrochemical impedance spectroscopy (EIS).

Modification of metal surfaces with complex molecules opens interesting opportunities to build additional functionality into these surfaces. In this work, self assembled monolayers (SAMs) based on the same photoswitchable azobenzene motif but with different head groups have been synthesized and their SAMs on Au(111)/Si substrates have been characterized. 3-[(4-phenylazo)phenoxy]propyl thiol (PAPT) and its acetyl group protected analog, 3-[(4-phenylazo)phenoxy]propyl thioacetate (PAPA), have been synthesized. SAMs from PAPT and PAPA have been characterized by infrared (IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), ellipsometry and cyclic voltammetry (CV). The SAM-forming units of both SAMs are the same, as confirmed by IR and XPS, and the SAMs have similar surface coverage, as evidenced by analysis of the reductive desorption peaks in CVs. The tilt angle of the azobenzene moiety was ca. 75° with respect to the surface normal as determined by IR spectroscopy, i.e., the molecules are lying quite flat on the gold surface. Despite similar surface coverages, the CVs for PAPT in aqueous perchlorate solution show a typical perchlorate adsorption peak to gold, whereas the corresponding experiments with PAPA show no perchlorate adsorption at all. In conclusion, SAM formation can lead to an increase in the number of electrochemically accessible surface sites on the final, SAM covered surface. Whether the amount of such sites increases or decreases, depends on the precursor. The precursor most likely affects the adsorption mechanism and thus the atomic surface structure of the metal at the metal/SAM interface. Thus, details of the SAM formation mechanism, which is affected by the precursor used, can have quite strong effects on the electrochemical properties, and likely also electrocatalytic properties, of the resulting modified surface.

This study focusses on the synthesis of polyaniline (PANI) and polyaniline base adsorbent utilizing Citrus limon leaves (CL) powder. The polyaniline base adsorbent with C. limon was synthesized using the same process as polyaniline synthesis, but with the addition of leaves powder. PANI and PANI based adsorbent with C. limon leaves powder (PANI/CL) were characterized by Fourier Transform Infra-Red (FTIR), UV-Visible spectroscopy and Scanning Electron Microscopy (SEM). This synthesized material was employed for the removal of congo red (CR) dye from industrial wastewater. Furthermore, the Langmuir, Temkin and Freundlich isotherms were also applied to evaluate experimental results. PANI is an efficient adsorbent for CR removal with 71.9 mg/g, while PANI/CL is an efficient adsorbent with 80 mg/g removal of dye according to a comparison of maximal adsorption capabilities. The data concludes that the prepared adsorbents could possibly be employed for the removal of toxic dyes from industrial effluents at large scale and ultimately could help in improving the environment.

In the current study, the degradation of reactive orange 122 (RO 122) dye was carried out under UV and gamma irradiation in presence of H 2 O 2 . The effect of variables such as UV exposure time, gamma-ray absorbed dose, initial concentration of dye and oxidant dose were investigated. The removal of 64.10, 58.84 and 55.46 (%) was observed for 50, 100 and 150 (mg/L) dye concentrations, respectively using UV radiation time of 150 (min). The degradation was enhanced to 80.39, 69.95 and 67.01 (%) when UV radiation was employed in the presence of H 2 O 2 (0.5 mL/L) for above concentrations respectively. The degradation was further improved to 97, 92.54 and 81.32 (%) using 5 kGy absorbed dose along with H 2 O 2 (0.5 mL/L). The reduction in chemical oxygen demand (COD) was 77, 64 and 57 (%) using UV/H 2 O 2 (0.5 mL/L), while 63, 56 and 53 (%) in case of gamma/H 2 O 2 for aforementioned concentrations. The removal efficiency ( G -value), dose constants ( k ), dose indispensable for 50, 90 and 99 (%) degradation ( D 0.5 , D 0.90 , and D 0.99 ) after the treatment with gamma radiation were determined. The G -value was noted as 0.46–0.0711 for 50–150 mg/L dye concentration for gamma irradiated samples which improved to 0.57–0.1204 for above mentioned concentrations in presence of H 2 O 2 . The FTIR analysis showed that all the peaks were disappeared using gamma/H 2 O 2 at 5 kGy absorbed dose except a minor peak of −CO stretching. The degradation mechanism of dye followed pseudo-first-order kinetics. A significant decrease in peak area was observed by the HPLC analysis after treating the dye samples with gamma/H 2 O 2 (0.5 mL/L) at absorbed dose of 5 kGy which has proven the process efficiency for dye degradation.

The ternary systems containing Water, Ascorbic acid (AA) and ZnSO 4 ·7H 2 O were investigated using three approaches namely volumetric studies, viscosity studies and conductance studies. The solvent systems used were 2, 4 and 6% (by weight) of AA in water. The studies were conducted at four temperatures (303.15–318.15 K with an interval of 5 K) and pressure 0.1 MPa with concentration of ZnSO 4 ·7H 2 O in the solution ranging from 0.01 to 0.12 m. Various parameters like partial molar volume ( ϕ v ), apparent molar volume ( ϕ v o ) $({\phi }_{\text{v}}^{\text{o}})$ , Hepler’s constant ( ( d 2 ϕ v o / d T 2 ) p ) $({({d}^{2}{\phi }_{\text{v}}^{\text{o}}/d{T}^{2})}_{p})$ , partial molar expansibility ( ϕ E o ) $({\phi }_{\text{E}}^{\text{o}})$ and transfer volume ( Δ t r ϕ v o ) $({{\Delta}}_{tr}{\phi }_{\text{v}}^{\text{o}})$ have been evaluated from volumetric studies. The viscosity studies have yielded Jones-Dole parameters (A and B) and free energy of activation per mole for solvent ( Δ μ 1 0 ‡ ) $({\Delta}{\mu }_{1}^{0{\ddagger}})$ and solute ( Δ μ 2 0 ‡ ) $({\Delta}{\mu }_{2}^{0{\ddagger}})$ . The conductance data has been used to calculate molar conductance (Λ m ), limiting molar conductance ( Λ m o ) $({{\Lambda}}_{\text{m}}^{\text{o}})$ and Walden product ( Λ m o η o ) $({{\Lambda}}_{\text{m}}^{\text{o}}{\eta }_{\text{o}})$ . The results of these studies agree with each other and have concluded the structure breaker behavior of ZnSO 4 ·7H 2 O in the solvent system containing AA and water.

In this study, theoretical calculations were made and interpreted to obtain chemical, nonlinear optical properties and antibacterial activity parameters of 14 registered heterocyclic 4, 5-dihydro-1H-1, 2, 4-triazole-5-one derivatives in the literature. For this purpose, first of all, 14 compounds registered in the literature and two main structures were optimized to find the minimum energy and the most stable structure by using the “B3LYP/6-311++G (d, p)” methods. HOMO–LUMO energies calculated from these optimized structures, energy differences and chemical parameters derived from HOMO–LUMO energies ( I; Ionization potential, A; electron affinity, ΔE; Energy Gap, χ; electronegative σ; molecular softness, ω; Electrophilic Index, ε; Nucleophilic Index, μ; Chemical Potential) values were determined. In addition to chemical parameters, polar calculations were made for nonlinear optical properties, and it was evaluated whether the compounds could be optical materials. Finally, the antimicrobial properties of the molecules were calculated theoretically and compared with the experimental results by calculating the volume.

Biodiesel is a promising clean energy supply that can be made from sustainable and low-grade fuels using a variety of methods. Transesterification is one of the processes that can occur in the manifestation of an effective catalyst. The catalyst may be homogeneous or heterogeneous in nature. This article reviews on the formation of biodiesel from various sources of waste oils using heterogeneous nanocatalysts. The manufacture of biodiesel using homogeneous and heterogeneous catalysis had been extensively studied, and new heterogeneous catalysts are constantly being examined. In general, homogeneous catalysts are effective at remodeling biodiesel with low free fatty acid (FFA) and single-origin feedstock having water. Heterogeneous catalysts, instead have higher interest, a wider scope of selectivity, better FFA, and better water adaptability. These properties are regulated by the number and intensity of active basic or acid sites. In order to achieve a viable alternative to conventional homogeneous catalysts for biodiesel processing, heterogeneous catalysts made from waste and biocatalysts are needed. Nanocatalysts have recently attracted interest due to their high catalytic performance under favorable operating conditions. This review evaluates the usage of heterogeneous nanocatalysts for the production of biodiesel from different sources of waste oil and the factors effecting the process of biodiesel production.