Yasin Ramazan Eker

Spent lithium batteries have become a strategic secondary resource for cobalt, nickel, manganese, and lithium due to the growth of the electronics industry. This paper investigates the effect of iron chloride salts on the dissolution rate of Co, Ni, and Mn in acidic chloride media. The study compares the leaching performance of these metals under oxidative and reductive conditions. Analytical-grade reagents, including ferric chloride (FeCl3), ferrous chloride tetrahydrate (FeCl2 · 4H2O), and hydrochloric acid (HCl), supply ferric ions (Fe3+), ferrous ions (Fe2+), and acidic chloride media (Cl-), respectively. The effects of solid/liquid ratio (2-6 g/L), agitation speed (50-300 rpm), temperature (30-60 °C), and concentrations of ferric chloride (0.05-0.3 M), ferrous chloride tetrahydrate (0.05-0.3 M), and HCl were studied.The removal of carbon affected the samples, as shown by XRD and SEM/EDX analysis, which revealed differences between non-calcined and calcined samples. Increasing ferric chloride concentration enhanced the leaching efficiency of Co, Ni, and Mn, with recoveries exceeding 95.0%. Ferrous chloride tetrahydrate was more effective in leaching Mn than Co and Ni. Consequently, oxidative leaching exhibited non-selectivity compared to reductive leaching. The leaching rate generally increased with higher temperature, agitation speed, acid concentration, and ferric or ferrous chloride levels. Since this work is industrial in scale, replicate tests demonstrated low variability and good reproducibility. A mixed-controlled shrinking core model best described the reactions and controlled both oxidative and reductive leaching rates. The activation energies were found to be 62.57 kJ/mol, 40.05 kJ/mol, and 58.08 kJ/mol for Co, Ni, and Mn in oxidative leaching, respectively. In reductive leaching, these values were 78.63 kJ/mol, 55.76 kJ/mol, and 87.00 kJ/mol.

Sille stone, which has mine area in the Sille District of Konya, is a mined structural mineral stone which has been used since ancient times. Structures normally react with acid rain in the nature and acids formed for various reasons. Building materials generally lose their physical and chemical properties because of their reaction with acids. The aim of this study is to investigate the resistance of historical structures, which have been built with Sille stone by various cultures and civilizations, by acid rain. The pH value of rainwater, between 5.6 and 6, shows acidic characteristics. It has been also shown that the pH value of acid rain can be dropped below 5-3 in some cases. In this study, first, the chemical and physical structure of Sille stone was determined. The strength of Sille stone against atmospheric conditions, in the aquatic environment, citric acid, sulfuric acid, nitric acid and their mixtures is tested to see the effect of acid rain. For this purpose, samples were taken from the stone quarries in Sille District, and they were cut as 7x7x7 cm3 dimensions depending on the TS 1926 Turkish Standards description for strength tests. All samples were put into the acidic mixtures. 1 molar concentration has been prepared for each acidic mixture. Test duration was kept as 3 and 6 months. ResuIts were evaluated in each 3 months. It was seen that, the sample taken from the mine gained strength at first, however, there were decreases in strength with time.

The Sille stone mined in the Sille Region of Konya province in Türkiye, is an andesitic rock. This stone is a material used in the construction of traditional and modern buildings. The Sille stone is cut while being used in buildings. The Sille stone powder (SSP) is formed during this cutting process. The SSPs cause environmental pollution. Therefore, this study was carried out to produce durable and eco-friendly new restoration mortars from the SSP that can be used in the restoration of historical buildings. The SSP composites were prepared by contributing SSP into epoxy and polyester resins in varied ratios such as 60‒75 wt.%. The effect of resin types and SSP contribution ratios on the elastic properties of epoxy resin (ER)/SSP and polyester resin (PR)/SSP composites was investigated by the ultrasonic pulse-echo method. Additionally, the morphology of these composites was investigated by scanning electron microscopy (SEM). Experimental results figured out that both longitudinal and shear wave velocity values of the PR/SSP composites were higher than of the ER/SSP composites. Furthermore, a linear increase was observed in the elastic properties of obtained composites with the increasing amounts of SSP.

Electric vehicles (EVs), which are environmentally friendly, have been used to minimize the global warming caused by fossil fuels used in vehicles and increasing fuel prices due to the decrease in fossil resources. Considering that the energy used in EVs is obtained from fossil resources, it is also important to store and use energy efficiently in EVs. In this context, recovery from a regenerative braking system plays an important role in EV energy efficiency. This paper presents a fuzzy logic-based hybrid storage technique consisting of a supercapacitor (SC) and battery for efficient and safe storage of a regenerative braking system. First, the constraints of the battery to be used in the EV for fuzzy logic control are identified. Then, the fuzzy logic system is created and tested in the ADVISOR and Siemens Simcenter Flomaster programs in the New European Driving Cycle (NEDC) driving cycle. A SC was selected for primary storage to prevent the battery from being continuously charged from regenerative braking, thus reducing its lifetime. In cases where the vehicle consumes more energy than the average energy consumption, energy consumption from the battery is reduced by using the energy stored in the SC, and the SC energy is discharged, making preparations for the energy that will come from the next regenerative braking. Thus, the high current values transferred to the battery during regenerative braking are effectively limited by the SC. In this study, the current values on the battery in the EV with a hybrid storage system decreased by 29.1% in the ADVISOR program and 28.7% in the Simcenter Flomaster program. In addition, the battery generated 46.84% less heat in the hybrid storage system. Thus, the heating and capacity losses caused by this current on the battery were minimized. The presented method provides more efficient energy management for EVs and plays an important role in maintaining battery health.

Surface plasmon technology is regarded as having significant potential for the enhancement of the performance of 2D oxide semiconductors, especially in terms of improving the light absorption of 2D MoO₃ photodetectors. An ultrathin MoO₃/Ir/SiO₂/Si heterojunction Schottky self-powered photodetector is introduced here to showcase positive photoconductivity. In wafer-scale production, the initial un-annealed Mo/2 nm Ir/SiO₂/Si sample displays a sheet carrier concentration of 5.76 × 10¹¹/cm², which subsequently increases to 6.74 × 10¹²/cm² after annealing treatment, showing a negative photoconductivity behavior at a 0 V bias voltage. This suggests that annealing enhances the diffusion of Ir into the MoO₃ layer, resulting in an increased phonon scattering probability and, consequently, an extension of the negative photoconductivity behavior. This underscores the significance of negative photoconductive devices in the realm of optoelectronic applications.

In this study, we delved into the influence of Ir nanofilm coating thickness on the optical and optoelectronic behavior of ultrathin MoO₃ wafer-scale devices. Notably, the 4 nm Ir coating showed a negative Hall voltage and high carrier concentration of 1.524 × 10¹⁹ cm⁻³ with 0.19 nm roughness. Using the Kubelka–Munk model, we found that the bandgap decreased with increasing Ir thickness, consistent with Urbach tail energy suggesting a lower level of disorder. Regarding transient photocurrent behavior, all samples exhibited high stability under both dark and UV conditions. We also observed a positive photoconductivity at bias voltages of >0.5 V, while at 0 V bias voltage, the samples displayed a negative photoconductivity behavior. This unique aspect allowed us to explore self-powered negative photodetectors, showcasing fast response and recovery times of 0.36/0.42 s at 0 V. The intriguing negative photoresponse that we observed is linked to hole self-trapping/charge exciton and Joule heating effects.