Reduction of sulfur oxides emissions via adsorptive desulfurization of transportation fuels using novel silica-based adsorbent.

Transportation fuels with high sulfur content are one of the primary contributors to air pollution because they emit massive quantities of sulfur oxides upon combustion. The emitted sulfur oxides undoubtedly contribute to global warming and climate change. Therefore, they should be minimized. The current study accurately describes a novel and direct synthetic pathway for the incorporation of sulfonic acid groups (-SO3H) into mesoporous silica surface. The structure of the prepared materials was confirmed using FTIR, SEM, BET, SA-XRD, TEM, and TGA techniques. The batch adsorption technique was used to carefully evaluate the adsorption efficiency of the prepared adsorbent towards dibenzothiophene (DBT). At optimal adsorption conditions, a maximum adsorption capacity of 75-mg DBT/g adsorbent was achieved. The desulfurization process fitted well to Langmuir and pseudo-second-order models. In addition, the desulfurization process was found to be a spontaneous and exothermic process. As a final point, the practical applicability of the prepared adsorbent, as well as its reusability, was properly investigated, and the results were promising.

Coaxial nanofibers of nickel/gadolinium oxide/nickel oxide as highly effective electrocatalysts for hydrogen evolution reaction.

Cost-effective, active and stable electrocatalysts are crucial for hydrogen production via electrocatalytic water splitting. Here, we describe the preparation of novel nanofibers (NF) made of Ni/Gd2O3/NiO heterostructures by electrospinning. The fabricated materials showed high electrocatalytic performance for hydrogen evolution reaction (HER) with onset potential values of 89 mV, which are very close to those of platinum (Pt). NiO chemical and electronic properties were successfully optimized in Ni/Gd2O3/NiO coaxial heterostructures; NiO NFs doped with Gd3+ significantly enhanced its electrical conductivity and promoted HER reaction kinetics. These NFs offer the distinct advantages of long-term durability and readiness for hydrogen production via HER, and also better performance than benchmark Pt catalysts. The successful fabrication of these metal oxide NFs and nanostructures may represent a new approach for the rational synthesis of efficient HER catalysts.

Atomic layer deposition of Pd nanoparticles on self-supported carbon-Ni/NiO-Pd nanofiber electrodes for electrochemical hydrogen and oxygen evolution reactions.

The most critical challenge in hydrogen fuel production is to develop efficient, eco-friendly, low-cost electrocatalysts for water splitting. In this study, self-supported carbon nanofiber (CNF) electrodes decorated with nickel/nickel oxide (Ni/NiO) and palladium (Pd) nanoparticles (NPs) were prepared by combining electrospinning, peroxidation, and thermal carbonation with atomic layer deposition (ALD), and then employed for hydrogen evolution and oxygen evolution reactions (HER/OER). The best CNF-Ni/NiO-Pd electrode displayed the lowest overpotential (63 mV and 1.6 V at j = 10 mA cm-2), a remarkably small Tafel slope (72 and 272 mV dec-1), and consequent exchange current density (1.15 and 22.4 mA cm-2) during HER and OER, respectively. The high chemical stability and improved electrocatalytic performance of the prepared electrodes can be explained by CNF functionalization via Ni/NiO NP encapsulation, the formation of graphitic layers that cover and protect the Ni/NiO NPs from corrosion, and ALD of Pd NPs at the surface of the self-supported CNF-Ni/NiO electrodes.

Magnetically modified hydroxyapatite nanoparticles for the removal of uranium (VI): Preparation, characterization and adsorption optimization.

Recently, magnetically modified nanomaterials have gained a great interest in the field of wastewater remediation. In this regard, the present work introduces a facile microwave-assisted pathway for the preparation of magnetically modified hydroxyapatite nanoparticles (MNHA) and evaluates its adsorption capability towards the removal of uranium (VI) ions from wastewaters. The prepared magnetic nanocomposite went through a full characterization procedure using different techniques, such as transmission electron microscope (TEM), X-ray diffraction (XRD), FT-IR, Brunauer-Emmett-Teller (BET) surface area measurements and magnetization curve. Involvement of the prepared MNHA in the remediation of wastewater containing U(VI) ions was investigated and the factors that influence the adsorption capacity were considered and optimized. The adsorption's optimum pH was found to be 5.0 and equilibrium was attended after 120 min. A maximum adsorption capacity of 310 mg/g was achieved after 120 min at 25 °C. The experimental data were well explained by Langmuir adsorption isotherm model. Kinetically, the adsorption process follows the pseudo-second order model. Thermodynamically, it is endothermic, irreversible and spontaneous adsorption process. Removal of U(VI) ions was found to take place via complex formation between the phosphate groups on the adsorbent and uranyl ions. The recovery of U(VI) ions from MNHA beads and the reusability of the spent beads were also explored. It was concluded that the prepared MNHA nanocomposite is simple, fast, ecofriendly adsorbent for the removal of U(VI) ions from water with excellent adsorption capacity.

Novel polyacrylamide-based solid scale inhibitor.

Novel solid-state phosphorus-containing polymer was synthesized, characterized and investigated as anti-scaling agent for the removal of alkaline earth metals ions from water. An optimization protocol for the sorption process of the metal ions on the polymer surface was proposed and executed. The protocol involved parameters such as pH, contact time, polymer dose, and the initial concentration of the metal ion. The optimum pH was found to be around seven for all of the tested metal ions. The maximum sorption capacities of the prepared polymer were 667, 794, 769 and 709 (mg/g) for Mg, Ca, Sr and Ba ions, respectively. Evaluation of the sorption process from the isotherm, kinetic and thermodynamic points of view was also studied. The experimental evidence revealed that the sorption obeys Langmuir isotherm model and follows a pseudo-second order mechanism. Moreover, the sorption process is exothermic. Possibility of polymer reuse was also investigated.

Magnetic graphene based nanocomposite for uranium scavenging.

Magnetic graphene based ferberite nanocomposite was tailored by simple, green, low cost and industrial effective method. The microstructure and morphology of the designed nanomaterials were examined via XRD, Raman, FTIR, TEM, EDX and VSM. The prepared nanocomposites were introduced as a novel adsorbent for uranium ions scavenging from aqueous solution. Different operating conditions of time, pH, initial uranium concentration, adsorbent amount and temperature were investigated. The experimental data shows a promising adsorption capacity. In particular, a maximum value of 455mg/g was obtained within 60min at room temperature with adsorption efficiency of 90.5%. The kinetics and isotherms adsorption data were fitted with the pseudo-second order model and Langmuir equation, respectively. Finally, the designed nanocomposites were found to have a great degree of sustainability (above 5 times of profiteering) with a complete maintenance of their parental morphology and adsorption capacity.