Aramid-Zirconia Nanocomposite Coating With Excellent Corrosion Protection of Stainless Steel in Saline Media.

Resistance to stainless steel corrosion in marine-based industries requires more research into materials with an improved surface and enhanced protection by utilizing surface coatings. Herein, a thermally stable aramid-zirconia nanocomposite has been successfully prepared using the sol-gel method to produce a zirconia network-structure bonded to the polymer chain. Using thermal gravimetric analysis (TGA), the residue mass of zirconia retained after the thermal degradation of aramid-zirconia film was determined and found to be 10% by mass. The investigated nanocomposite (using 10% zirconia) was coated on the stainless-steel surface through a facile and effective spin coating method and its protection was examined in saline solution (3.5% NaCl). The aramid-zirconia nanocomposite coating (Ar-Zr10) was found to provide an outstanding corrosion resistance to steel surfaces which led to protecting it against the corrosive marine environment. The electrochemical impedance (EIS) measurements were carried out to evaluate steel resistance against dissolution in chloride solution in the absence and presence of the investigated coatings showed a corrosion protection efficiency of 99.3% using Ar-Zr10 compared to 92.1% using pure aramid. Moreover, the potentiodynamic polarization (PDP) plots showed a pronounced decrease in the corrosion current values which confirmed the formation of a passive layer which mitigated the corrosion reaction and ions diffusion. The water contact angle of stainless-steel coated with pure aramid and the aramid-zirconia was found to be 84.2° and 125°, respectively, confirming the hydrophobic nature of the hybrid coating Ar-Zr10. On the other hand, the results achieved through the electrochemical and surface techniques were used to clarify the protection mechanism. The aramid-zirconia nanocomposite coating showed a remarkable protection performance by controlling the charge transfer at the interface between the steel alloy and the electrolyte which prevented the alloy dissolution.

CeO2-CB nanocomposite as a novel SALDI substrate for enhancing the detection sensitivity of pharmaceutical drug molecules in beverage samples.

SALDI-MS analysis of pharmaceutical drug molecules (amitriptyline, imipramine and promazine) using carbon-based substrates, namely, activated charcoal (AC), carbon nanotubes (CNTs), carbon black (CB), graphene (rGO), graphene oxide (GO) and graphite, was explored and compared with the conventional organic matrix of MALDI. CB exhibited superior performance with respect to the other substrates in terms of detection sensitivity. Despite the effectiveness of CB to detect all drug molecules, it demonstrated a number of background signals, which may be an issue for the analysis of other molecules in the future. Therefore, for the first time, a CeO2-CB nanocomposite was synthesized and applied as a novel SALDI substrate to minimize the background signals and stabilize CB when exposed to high laser power. The nanocomposite was characterized using XRD, TEM, FTIR, UV-Vis and N2 sorpometry. The spectrum obtained using the novel nanocomposite in the absence of the drug molecules showed minimal background signals compared to CB. Additionally, the CeO2-CB nanocomposite enhanced the detection sensitivity of the drug molecules with a limit of detection (LOD) of 100 ng/mL. This active substrate nanocomposite was further applied for the analysis of drug-spiked beverages without sample pretreatment or extraction, mimicking cases encountered by forensic toxicologists. All of the drugs and/or their adducts were detected in the drug-spiked beverage samples.

Controlled Synthesis of ZrO2 Nanoparticles with Tailored Size, Morphology and Crystal Phases via Organic/Inorganic Hybrid Films.

In this investigation, well defined mesoporous zirconia nanoparticles (ZrO2 NPs) with cubic, tetragonal or monoclinic pure phase were synthesized via thermal recovery (in air) from chitosan (CS)- or polyvinyl alcohol (PVA)-ZrOx hybrid films, prepared using sol-gel processing. This facile preparative method was found to lead to an almost quantitative recovery of the ZrOx content of the film in the form of ZrO2 NPs. Impacts of the thermal recovery temperature (450, 800 and 1100 °C) and polymer type (natural bio-waste CS or synthetic PVA) used in fabricating the organic/inorganic hybrid films on bulk and surface characteristics of the recovered NPs were probed by means of X-ray diffractometry and photoelectron spectroscopy, FT-IR and Laser Raman spectroscopy, transmission electron and atomic force microscopy, and N2 sorptiometry. Results obtained showed that the method applied facilates control over the size (6-30 nm) and shape (from loose cubes to agglomerates) of the recovered NPs and, hence, the bulk crystalline phase composition and the surface area (144-52 m2/g) and mesopore size (23-10 nm) and volume (0.31-0.11 cm3/g) of the resulting zirconias.

The effect of surface charge on photocatalytic degradation of methylene blue dye using chargeable titania nanoparticles.

Herein, a simple approach based on tailoring the surface charge of nanoparticles, NPs, during the preparation to boost the electrostatic attraction between NPs and the organic pollutant was investigated. In this study, chargeable titania nanoparticles (TiΟ2 NPs) were synthesized via a hydrothermal route under different pH conditions (pH = 1.6, 7.0 and 10). The prepared TiΟ2 NPs were fully characterized via various techniques including; transmission electron microscopy (TEM), X-ray diffraction (XRD), N2 adsorption/desorption, X-ray photoelectron spectroscopy (XPS), Ultraviolet-visible spectroscopy (UV-Vis) and dynamic light scattering (DLS). The influence of the preparation pH on the particle size, surface area and band gap was investigated and showed pH-dependent behavior. The results revealed that upon increasing the pH value, the particle size decreases and lead to larger surface area with less particles agglomeration. Additionally, the effect of pH on the surface charge was monitored by XPS to determine the amount of hydroxyl groups on the TiO2 NPs surface. Furthermore, the photocatalytic activity of the prepared TiΟ2 NPs towards methylene blue (MB) photodegradation was manifested. The variation in the preparation pH affected the point of zero charge (pHPZC) of TiO2 NPs, subsequently, different photocatalytic activities based on electrostatic interactions were observed. The optimum efficiency obtained was 97% at a degradation rate of 0.018 min-1 using TiO2 NPs prepared at pH 10.