Photocatalytic Degradation of Bisphenol A (BPA) Present in Aqueous Solution Using g-C3N4 Nanosheets Under Solar Light Irradiation

A graphite-like carbon nitride (g-C3N4) nanosheet sample was synthesized from a melamine precursor by a method of simple direct heating in a semi-closed system followed by thermal oxidation etching at 550 °C for 12 h. The sample was labelled as (g-C3N412h) and was systematically characterized. Moreover, the results were then compared with a pristine g-C3N4 sample for the degradation of Bisphenol A (BPA) present in water. Bisphenol A (BPA) is an endocrine disruptor. It is known that the BPA is one of the most harmful organic materials and that it does not degrade easily in the environment. It was therefore selected as a target to test the photocatalytic activity of prepared carbon nitride nanosheets under direct solar irradiation. The results showed the structure of the g-C3N4 nanosheets when the sample had been treated for a longer time compared to the regular treatment time.  The optical band gap results remained the same, indicating the existence of a g-C3N4 backbone structure. However, the XPS and FTIR spectra showed some modification on g-C3N4 after longer etching treatment time such as the C-H, CO and N pyridinic structure. The photocatalytic degradation of Bisphenol A by the g-C3N4 nanosheets under solar irradiation was much better (around 60%) than that with the g-C3N43h bulk sample (around 30%). This enhanced  photocatalytic activity can be attributed to multiple factors such as the smaller particle size, rich carbon surface and high surface area exhibited by the g-C3N4 nanosheets. This further indicates that g-C3N4 can be used with solar irradiation to treat wastewater containing endocrine disruptor chemicals

An Improved Mnemonic Device for Thermodynamic Relations

An improved mnemonic device for thermodynamic relations between state variables and potentials was proposed in the form of a thermodynamic circle. Based on separating the Born square into an inner square (T, P, V, and S) and an outer circle (G, A, U, and H), relations such as Legendre transforms, Maxwell equations, equations to compute variables, and differential equations for thermodynamic variables can be recalled easily. The thermodynamic circle has a cross-arrow at its center and can be used to intuitively determine the sign of all thermodynamic relations

Lotus-bud like hexagonal ZnO/g-C3N4 composites for the photodegradation of benzene present in aqueous solution

This study used a one-pot paralysis approach to combine hexagonal ZnO lotus buds with graphitic carbon nitride (g-C3N4) nanosheets to create ZnO/g-C3N4 composites. For the purpose of investigating the charge carrier interface for photocatalytic improvement, ZnO/g-C3N4 composites in various molar ratios of ZnO and g-C3N4 were produced. X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectroscopy, ultraviolet–visible diffuse reflectance spectroscopy (UV-DRS), and electrochemical impedance spectroscopy (EIS) were used to investigate the coupling of the ZnO particles to the g-C3N4 nanosheets. For the degradation of benzene, pure ZnO, pure g-C3N4, and their composites were utilized. High purity ZnO with a clearly defined hexagonal wurtzite crystal phase was shown by elemental mapping and XRD patterns, and optical characteristics measured by UV-DRS, PL spectroscopy, and spectroscopy of electrochemical impedance (EIS). For the degradation of benzene, pure ZnO, pure g-C3N4, and their composites were employed. High purity and a clearly defined hexagonal wurtzite crystal phase were revealed by elemental mapping and XRD patterns for ZnO, and optical properties examined by UV-DRS, PL spectroscopy, and EIS revealed improved visible light absorbance with a substantially reduced electron-hole recombination rate. The prepared samples were applied to test the photodegradation of benzene in the presence of visible light. The 40 %ZnO/g-C3N4 sample shown the largest photocatalytic activity for the degradation among all the produced samples, with high stability up to five cycles. The combined photocatalyst and degradation mechanism were proposed as a Z-scheme

Recent Developments and Advancements in Graphene-Based Technologies for Oil Spill Cleanup and Oil–Water Separation Processes

The vast demand for petroleum industry products led to the increased production of oily wastewaters and has led to many possible separation technologies. In addition to production-related oily wastewater, direct oil spills are associated with detrimental effects on the local ecosystems. Accordingly, this review paper aims to tackle the oil spill cleanup issue as well as water separation by providing a wide range of graphene-based technologies. These include graphene-based membranes; graphene sponges; graphene-decorated meshes; graphene hydrogels; graphene aerogels; graphene foam; and graphene-coated cotton. Sponges and aerogels modified by graphene and reduced graphene oxide demonstrated effective oil water separation owing to their superhydrophobic/superoleophilic properties. In addition, oil particles are intercepted while allowing water molecules to penetrate the graphene-oxide-coated metal meshes and membranes thanks to their superhydrophilic/underwater superoleophobic properties. Finally, we offer future perspectives on oil water separation that are hindering the advancements of such technologies and their large-scale applications