Photovoltage response of (XZn)Fe2O4-BiFeO3 (X=Mg, Mn or Ni) interfaces for highly selective Cr3+, Cd2+, Co2+ and Pb2+ ions detection

Recent Advances in Functionalized Mesoporous Silica Frameworks for Efficient Desulfurization of Fuels

Considerable health and climate benefits arising from the use of low-sulfur fuels has propelled the research on desulfurization of fossil fuels. Ideal fuels are urgently needed and are expected to be ultra-low in sulfur (10-15 ppm), with no greater than 50 ppm sulfur content. Although several sulfur removal techniques are available in refineries and petrochemical units, their high operational costs, complex operational needs, low efficiencies, and higher environmental risks render them unviable and challenging to implement. In recent years, mesoporous silica-based materials have emerged as promising desulfurizing agents, owing to their high porosity, high surface area, and easier functionalization compared to conventional materials. In this review, we report on recent progress in the synthesis and chemistry of new functionalized mesoporous silica materials aiming to lower the sulfur content of fuels. Additionally, we discuss the role of special active sites in these sorbent materials and investigate the formulations capable of encapsulating and trapping the sulfur-based molecules, which are challenging to remove due to their complexity, for example the species present in JP-8 jet fuels.

Lattice substitution and desulfurization kinetic analysis of Zn-based spinel sorbents loading onto porous silicoaluminophosphate zeolites

Green Zn-based spinel sorbents for hot coal gas desulfurization have been developed with the assistance of optimization procedures. The pilot study highlights an outstanding ordered mesoporous support (S_BET = 323 m² g^-1, Da = 4.3 nm) of SAPO-34@as-prepared SBA-15 (SS) for loading active metal oxides. ZnCo₂O₄ spinel loaded onto SS (ZnCo₂/SS) exhibits a prominent desulfurization performance compared to other sorbents whose partial Co is substituted by Mn or Fe in spinel B-site, owing to the slight effect of PO₄^3- in SS. After systematic evaluation on role of sulfidation condition, 50 wt% ZnCo₂/SS sorbent possesses the sulfur storage capacity of 138.08  mg g^-1at550 °C and little loss of active species in 5 desulfurization-regeneration cycles. Results of high resolution transmission electron microscopy (HRTEM), Brunauer-Emmett-Teller (BET), X-ray photoelectron spectroscopy (XPS) etc. demonstrate that 70.42% of initial sulfur capacity of ZnCo₂/SS presented in the 2nd utilization is associated with zinc evaporation, existence of high stable sulfides and partial sintering. The improved deactivation kinetic model suitably describes that the H₂S concentration distribution relates with the spatial position of fixed-bed reactor and desulfurization time.

G. S, Suvina V, Sakar M, Balakrishna RG. Perovskite nanomaterials as optical and electrochemical sensors

The perovskite family is comprised of a great number of members because of the possible and flexible substitution of numerous ions in its system.

Selective adsorption of uranyl and potentially toxic metal ions at the core-shell MFe2O4-TiO2 (M=Mn, Fe, Zn, Co, or Ni) nanoparticles

Potentially toxic metal ions (Xⁿ⁺: Rb⁺, Sr²⁺, Cr³⁺, Mn²⁺, Ni²⁺, Zn²⁺, Cd²⁺) usually coexist with uranyl (UO₂⁺), which will have a great influence on the selective adsorption process. Here, the core-shell MFe₂O₄-TiO₂ (M = Mn, Fe, Zn, Co, or Ni) nanoparticles were synthesized and assessed as new selective adsorbents. The results reveal that TiO₂(101) preferentially grows along the MFe₂O₄(311)/(111) orientation. The M²⁺ ions as the mediators transfer the holes from MFe₂O₄ to TiO₂, at the conduction bands. On the TiO₂(101) surfaces and TiO₂(101)-TiO₂(101) gaps, the paired active electrons mainly complex with water molecules as hydroxyl radicals to capture Xⁿ⁺ ions, forming an ion layer to block UO₂²⁺ from being adsorbed. Simultaneously, it should be noted that an interesting adsorption pathway was UO₂²⁺ being horizontally and irreversibly adsorbed in the MFe₂O₄(311)/(111)-TiO₂(101) interface, and therein, the stable adsorption capacity was found to be 66.78 mg g^-1 in the MnFe₂O₄(311)/(111)-TiO₂(101) interface. Finally, a mechanism of hybrid orbitals between MnFe₂O₄-TiO₂ and UO₂⁺-Xⁿ⁺ was proposed.

Improving photoelectrochemical reduction of Cr(VI) ions by building α-Fe2O3/TiO2 electrode

Photoelectrochemical process is an environmentally friendly technology and has a wide application in the control of environmental pollutants. Efficient nanophotocatalysts responsive to visible light are still highly attractive. In this work, α-Fe₂O₃/TiO₂ were grown on fluorine doped tin oxide (FTO) substrates by hydrothermal method for photoelectrochemical reduction of Cr(VI). Compared with the separate α-Fe₂O₃ and TiO₂ electrodes, the composite α-Fe₂O₃/TiO₂ electrodes show higher photocurrent density. Under visible light irradiation, 100% removal efficiency of Cr(VI) was obtained after 40 min treatment. The composite α-Fe₂O₃/TiO₂ electrodes showed an enhanced absorbance in visible light region and had good stability to photoelectrochemical reduction of Cr(VI). The role of hole scavengers (citric acid and oxalic acid) and pH values was systematically investigated. This novel intensification approach provides new insight on the application of photoelectrochemical reduction in environmental remediation.