XPS Study on Calcining Mixtures of Brucite with Titania

Biodiesel production through transesterification of waste Pistacia- Terebinthus Oil by pharmaceutical waste as a heterogeneous catalyst: A sustainable solution for reducing external costs

A catalyst from the pharmaceutical waste of calcium and magnesium tablets was synthesized for biodiesel production from waste Pistacia-Terebinthus (PT) oil with the aim of creating added value and presenting a new approach for the management of such wastes. For this purpose, magnesium and calcium tablet wastes with a mass ratio of 70:30 (wt%) were calcined. The catalyst was investigated by several methods, such as thermal gravimetric analysis, X-ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, Brunauer-Emmett-Teller analysis, X-ray photoelectron spectroscopy, and CHNS/O elemental analysis. The high specific surface area of the catalyst confirms that the utilized synthesis method resulted in the formation of a high number of active sites in its structure, which allows it to function as a suitable catalyst for this reaction. Furthermore, the impact of effective parameters on the treansestrification reaction was optimized and investigated by designing the experiments and applying the RSM method. The maximum mass yield of 96 % was obtained in optimal conditions (temperature of 70 °C, catalyst loading of 4.498 wt%, methanol:oil ratio of 1.968 (vol:vol), and reaction time of 120 min). The reusability of the catalyst was investigated in four successive cycles. The mass yield of the last test declined from 96 % to 71.4 %. Gas chromatography-mass spectrometry analysis of the produced biofuel revealed that it comprises 91.37 % methyl ester compounds (64.28 % 12-Octadecenoic Acid, Methyl Ester). To evaluate the external costs of biofuel (B100) and compare it with diesel, combustion simulation was done with Diesel-RK software, which showed that its external costs were 0.05388 (€/Lit fuel) less than those of diesel.

Comment on "Bipolar Resistive Switching in Lanthanum Titanium Oxide and an Increased On/Off Ratio Using an Oxygen-Deficient ZnO Interlayer"

The Mott-based resistive switching random access memory (RRAM) has been considered as a promising candidate for next-generation nonvolatile mass storage. Its performance relies on the oxygen migration process. In ACS Appl. Mater. Interfaces 2022, 14, 17682-17690, Wang et al. demonstrated that inserting a ZnO layer between the top tungsten electrode and the lanthanum titanium oxide (LTO) layer can improve the ON/OFF current ratio of the RRAM. This improvement was attributed to the increased oxygen vacancies in the ZnO layer. We argue their interpretation with the role, significance, and statistics of the oxygen vacancy in the samples. Our experimental evidence contradicts their claim, and we propose that hydroxy groups should be the responsible candidate for their claimed oxygen vacancy peak at around 531-532 eV in the O 1s photoelectron spectroscopy observed in their samples. We thus propose an alternative mechanism for the ON/OFF ratio enhancement with the ZnO interlayer: the ZnO layer prevents the LTO oxygen and hydroxy groups migration and from reacting with the multivalent tungsten electrode.