Saad Al-Saadi

Zinc (Zn) alloys are among the few metallic materials that possess characteristics suitable for their application as temporary, biodegradable implants. This study investigated the combined role of mechanical stress and corrosive simulated body fluid (SBF) that can cause catastrophic and sudden fracture, which is called stress corrosion cracking (SCC). This is a relatively rarely investigated domain of Zn alloys in the context of their application as implants, even though metallic implants are known to suffer SCC. While most in vitro studies of SCC of bioimplants have employed SBFs that simulate only the inorganic constituents, this study investigated the role of adding the major organic constituent of body fluid (i.e., protein) to SBF in corrosion, and SCC in particular. While protein addition reduced corrosion resistance (by >100%) during prolonged immersion, it unexpectedly improved resistance to SCC (by >50%). Our findings also indicate that, unlike other alloys, the Zn alloy showed minimal intergranular stress corrosion cracking (IGSCC) despite the presence of extensive grain boundary precipitates. Detailed electron microscopy provided the key to explaining this unexpected behavior.

Polyethersulfone (PES) ultrafiltration membranes were modified with phosphoric acid–functionalized TiO ₂ nanoparticles (0–1 wt%) via phase inversion to enhance permeability, antifouling performance, and dye removal for wastewater treatment. Structural and morphological analyses confirmed the successful modification and uniform incorporation of TiO ₂ within the PES matrix. The membrane containing 0.5 wt% TiO ₂ exhibited optimal performance, achieving the lowest contact angle (~39°), highest porosity (~65.5%), and maximum pure water flux (~292 L·m ⁻² ·h ⁻¹ ), compared to 204 L·m ⁻² ·h ⁻¹ for pristine PES. Rhodamine B rejection exceeded 85%, driven by electrostatic interactions between phosphate groups and cationic dye molecules. Fouling tests using bovine serum albumin revealed a high FRR (~92%) and reduced irreversible fouling. Excessive TiO ₂ loading led to nanoparticle agglomeration and reduced permeability.

Polyethersulfone (PES) is widely used as the premier material for various membrane processes, including membrane fabrication and development, and as a support for thin film composite membranes. Thi...

Nickel is widely deployed in caustic service, yet its native Ni(OH)₂/NiOOH passive film raises concerns for long service life. Graphene has emerged as a promising corrosion barrier; however, its long-term durability in strongly alkaline media remains largely unexplored. The extended exposure period in a highly caustic solution is a novel aspect of the present work, distinguishing it from previous studies that predominantly examined short-term exposures or focused on neutral and acidic environments. Here, we present the systematic assessment of low-pressure CVD-grown multilayer graphene (MLG) coatings on Ni in highly caustic (0.5 M NaOH) for up to 80 days. Two architectures, a conformal, robust MLG coating (Gr_Ni) and a less robust film (Gr_Ni_DF), were benchmarked against bare Ni. PDP and EIS reveal that Gr_Ni initially delivers nearly 2 orders of magnitude enhancement, as evidenced by the low frequency impedance, accompanied by a broad, high-fidelity capacitive plateau; the impedance still maintains 1.3–1.5 orders of magnitude superior after prolonged exposure. In contrast, Gr_Ni_DF undergoes progressive degradation, affording a modest 2-fold benefit over time, consistent with defect-mediated electrolyte ingress. SEM morphologies further corroborate these trends, confirming the superior structural stability of Gr_Ni under extended alkaline immersion.

Advanced oxidation methods are powerful tools that can be used to remove dyes from effluents of wastewater. This study focuses on the Fenton oxidation method as an alternative one used for the removal of azo dyes from synthetic wastewater before discharge from textile industry effluents. The major system parameters associated with this process are dye concentrations of 15, 30, 60, and 100 mg/L, pH of 2.0, 3.0, 4.0 and 5.0, Ferrous ion concentration (Fe²⁺) of 5, 10, 15 and 20 mg/L, hydrogen peroxide (H2O2) of 10, 20, 40 and 80 mg/L, reaction temperature of 25, 35, 45 and 55 °C. The results indicated that optimal conditions of the maximum dye removal 99% were achieved at 15 mg/L, 4.0, 20 mg/L, 80 mg/L, and 35 °C of the azo concentration, pH, Fe²⁺ concentration, H₂O₂ concentration, and temperature, respectively. Experimental results showed that increased H₂O₂ and Fe²⁺ concentrations increase the dye removal percentage, demonstrating the synergistic effect of these two reagents in the Fenton oxidation method.

Membrane distillation (MD) faces challenges in the form of diminished permeate flux attributed to the loss of hydrophobicity with time. Nanomaterials play an essential role in enhancing the performance of MD through membrane modification during formation or surface modification. Numerous nanomaterials have been investigated, particularly for flat sheet polyvinylidene fluorides (PVDF). These nanomaterials have provided unparalleled opportunities for the MD process application, such as increased water desalination efficiency, improved membrane durability, and reduced energy consumption. Adding nanomaterials changed the MD membrane properties, such as the size of the pores, porosity, and hydrophobicity, which significantly enhanced MD efficiency. However, some are sometimes exposed to peel-off or release to the distillate, which causes second contamination (leaching of nanomaterials). This review provides a comprehensive insight into the impact of different nanomaterials on the performance of flat sheet PVDF membranes and their stability over extended operations in MD for water desalination.