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Used cooking oils (UCOs) have a high potential as renewable fuels for the maritime shipping industry. However, their corrosiveness during storage and usage are some of the concerns yet to be investigated for addressing compatibility issues. Thus, the corrosion of steels and copper exposed to the UCOs was studied through the immersion of metal rods for different periods. The changes on the rod surfaces were analyzed with a scanning electron microscope (SEM). After the immersion, the copper concentration dissolved in the bio-oils was measured using inductively coupled plasma-optical emission spectrometry (ICP-OES). The free fatty acids and glycerides were analyzed using gas chromatography with flame ionization detection (GC-FID). The acid number (AN), water concentration, as well as density and kinematic viscosity of the bio-oils were determined with standard methods. The UCOs with the highest water content were corrosive, while the oils with lower water concentrations but higher ANs induced lower corrosion. After mixing two different UCOs, the metal corrosion decreased with an increasing concentration of the oil with lower corrosive properties. The lower corrosion properties were most likely due to the monounsaturated fatty acids, e.g., oleic acid in oils. These acids formed a barrier layer on the rod surfaces, thereby inhibiting the permeation of oxygen and water to the surface. Even adding 0.025 wt% of tert-butylamine decreased the corrosivity of UCO against polished steel rod. The results suggested that mixing several oil batches and adding a suitable inhibitor reduces the potential corrosive properties of UCOs.

In this study, we tested several amino acids as eco-friendly inhibitors against corrosion of mild steel by used cooking oils (UCOs). The corrosion inhibition was studied by immersing mild steel rods in the UCOs and reference fresh rapeseed and olive oils mixed with amino acids. The immersion tests were conducted at room temperature for three days. The roles of water and bio-oil preservatives (formic and propionic acids) in the corrosion were explored. The mild steel surface morphology changes after exposure to the oils were analyzed with a scanning electron microscope coupled with an energy dispersive spectroscope (SEM-EDS). The concentration of iron dissolved in the oils was determined with a spectrophotometer. A thick layer was analyzed on the surfaces of the mild steel rods immersed in the oils containing formic or propionic acid and water. This layer provided a minor barrier against corrosion. According to the Fourier transform infrared spectrometer (FTIR) analytical results, the layer consisted of an acid and iron salt mixture. All the tested amino acids decreased the concentration of dissolved iron in the UCOs; particularly, cationic amino acids, L-lycine and L-arginine showed adequate corrosion inhibition properties at low concentrations.

Waste-printed circuit boards (WPCBs) account for approximately 3–6 wt% of total electronic waste. Due to their content of thermosetting materials and added brominated fire retardants, their recycling and disposal is difficult and not eco-friendly. Pyrolysis as a thermal degradation process may assist in the solution of this problem. In addition, using biomass as an additive can upgrade the bio-oil and fix bromines in the char. In this study, cotton stalk (CS) is chosen as an additive and kinetic of the pyrolysis of three samples namely: PCB, CS, and CS:PCB (50:50) were investigated by the thermogravimetric analyzer (TGA) at heating rates of 5, 10, and 15 K/min. Three non-isothermal methods: FWO, KAS, and Starink were found in good agreement with the TGA data; however, the FWO method was more efficient in the description of the degradation mechanism of solid-state reactions. For CS and CS:PCB (50:50), α was increased from 0.2 to 0.9 with the FWO method, and calculated Eα values were found in the range of 121.43–151.88 and 151.60–105.67 kJ/mol in zone 1, while 197.06–79.22 and 115.90–275.06 kJ/mol in zone 2, respectively. Whereas, for PCB in zone 1, Eα values were found to be in the range of 190.23–93.88 kJ/mol. The possible decomposition mechanism was determined by the Criado method, which was in agreement with the mechanism model for reaction order n = 3. The oil product was also analyzed using Fourier-Transform Infrared Spectroscopy analysis.

Used cooking oils (UCOs) have a high potential as renewable fuels for the maritime shipping industry. However, their corrosiveness during storage and usage are some of the concerns yet to be investigated for addressing compatibility issues. Thus, the corrosion of steels and copper exposed to the UCOs was studied through the immersion of metal rods for different periods. The changes on the rod surfaces were analyzed with a scanning electron microscope (SEM). After the immersion, the copper concentration dissolved in the bio-oils was measured using inductively coupled plasma-optical emission spectrometry (ICP-OES). The free fatty acids and glycerides were analyzed using gas chromatography with flame ionization detection (GC-FID). The acid number (AN), water concentration, as well as density and kinematic viscosity of the bio-oils were determined with standard methods. The UCOs with the highest water content were corrosive, while the oils with lower water concentrations but higher ANs induced lower corrosion. After mixing two different UCOs, the metal corrosion decreased with an increasing concentration of the oil with lower corrosive properties. The lower corrosion properties were most likely due to the monounsaturated fatty acids, e.g., oleic acid in oils. These acids formed a barrier layer on the rod surfaces, thereby inhibiting the permeation of oxygen and water to the surface. Even adding 0.025 wt% of tert-butylamine decreased the corrosivity of UCO against polished steel rod. The results suggested that mixing several oil batches and adding a suitable inhibitor reduces the potential corrosive properties of UCOs.

Funding Information: This research was supported by the national projects of the Ministry of Education and Science of Ukraine: “Synthesis, physico-chemical and thermodynamic properties of nanosized and nanostructured materials for electrochemical systems” (No. 0120U102184). This work was partly supported by the Academy of Finland project (Decision Number 311537) as part of the activities of the Johan Gadolin Process Chemistry Centre at Åbo Akademi University. Publisher Copyright: © 2021, The Minerals, Metals & Materials Society. Copyright: Copyright 2021 Elsevier B.V., All rights reserved. Discoveries of new energy materials with unique properties and wider thermal stability ranges enable sustainable developments toward a low-carbon society. In this work, phase stabilities and thermodynamic properties of selected compounds in the Ag-Te-Cl system with potential application as energy materials have been critically reviewed and experimentally investigated. Based on the literature data on phase formations in the AgCl-Ag2Te-Te part of the Ag-Te-Cl system and the results of electromotive force (EMF) measurements in this work, formations of the Ag19Te6Cl7, Ag10Te4Cl3, Ag5Te2Cl, and Ag23Te12Cl compounds below 500 K were established. The EMF measurements were performed in carefully built galvanic cells with positive electrodes prepared from finely ground mixtures of pure substances Ag, Te, and AgCl. Based on the temperature dependences of the EMF of the cells, the standard thermodynamic quantities of the ternary compounds of the Ag-Te-Cl system were experimentally determined for the first time.

Equilibrium phase formations below 600 K in the parts Ag2Te–FeTe2–F1.12Te–Ag2Te and Ag8GeTe6–GeTe–FeTe2–AgFeTe2–Ag8GeTe6 of the Fe–Ag–Ge–Te system were established by the electromotive force (EMF) method. The positions of 3- and 4-phase regions relative to the composition of silver were applied to express the potential reactions involving the AgFeTe2, Ag2FeTe2, and Ag2FeGeTe4 compounds. The equilibrium synthesis of the set of phases was performed inside positive electrodes (PE) of the electrochemical cells: (−)Graphite ‖LE‖ Fast Ag+ conducting solid-electrolyte ‖R[Ag+]‖PE‖ Graphite(+), where LE is the left (negative) electrode, and R[Ag+] is the buffer region for the diffusion of Ag+ ions into the PE. From the observed results, thermodynamic quantities of AgFeTe2, Ag2FeTe2, and Ag2FeGeTe4 were experimentally determined for the first time. The reliability of the division of the Ag2Te–FeTe2–F1.12Te–Ag2Te and Ag8GeTe6–GeTe–FeTe2–AgFeTe2–Ag8GeTe6 phase regions was confirmed by the calculated thermodynamic quantities of AgFeTe2, Ag2FeTe2, and Ag2FeGeTe4 in equilibrium with phases in the adjacent phase regions. Particularly, the calculated Gibbs energies of Ag2FeGeTe4 in two different adjacent 4-phase regions are consistent, which also indicates that it has stoichiometric composition.

The equilibrium phase space of the Ag–Fe–X–Se (X: Ge, Sn) systems in the parts Ag8XSe6–XSe–FeSe2–AgFeSe2–Ag8XSe6 consists of four quaternary-phase regions formed with the participation of low-temperature modifications of the Ag2FeGeSe4 and Ag2FeSnSe4 compounds. The kinetic barriers of the formation of equilibrium four-phase regions that are observed under conditions of vacuum ampoule synthesis below 600 K were overcome by synthesis of phases at the positive electrodes of electrochemical cells (ECCs): (−)C | Ag | SE | R (Ag+) | PE | C(+), where C is graphite, Ag is left (negative) electrode, SE is the solid-state electrolyte, PE is the right (positive) electrode, and R (Ag+) is the region of Ag+ diffusion into PE. Silver cations Ag+ that shifted from the left to the right electrode of ECCs acted as the seed centers of an equilibrium set of phases. Based on the temperature dependences of the EMF of the cells in the temperature range 430–485 K, the standard thermodynamic functions of the Ag2FeGeSe4 and Ag2FeSnSe4 compounds were calculated for the first time. The observed experimental results and thermodynamic calculations are in good agreement.

Besides the widely applied hydropower, wind farms and solar energy, biomass and municipal and industrial waste are increasingly becoming important sources of renewable energy. Nevertheless, fouling, slagging and corrosion associated with the combustion processes of these renewable sources are costly and threaten the long-term operation of power plants. During a high-temperature biomass combustion, alkali metals in the biomass fuel and the ash fusion behavior are the two major contributors to slagging. Ash deposits on superheater tubes that reduce thermal efficiency are often composed of complex combinations of sulfates and chlorides of Ca, Mg, Na, and K. However, thermodynamic databases involving all the sulfates and chlorides that would favor a better understanding and control of the problems in combustion processes related to fouling, slagging and corrosion are not complete. In the present work, thermodynamic properties including solubility limits of some phases and phase mixtures in the K2SO4-(Mg,Ca)SO4 system were reviewed and experimentally investigated. Based on the new and revised thermochemical data, binary phase diagrams of the K2SO4-CaSO4 and K2SO4-MgSO4 systems above 400 °C, which are of interest in the combustion processes of renewable-energy power plants, were optimized.

The advancement in technology has resulted in the development of newer and improved electrical products. The older products are becoming obsolete and are discarded as waste at a continuously increasing trend. Printed circuit board (PCB) is the main focus of electronic waste recycling because of the inherently high value of contained metals such as gold and copper. Hydrometallurgical route, which is often used to recover the metals, does not take into account the non-metallic PCB fractions. These non-metallic fractions may end up in landfills or incinerated which leads to secondary pollution. In this work, the use of the leached PCB waste fraction as reductant in primary metal smelting operations and solid state reduction is investigated. Laboratory-scale experiments and thermodynamic modelling were performed to simulate solid state reduction of hematite (Fe2O3) using various blends of PCB and graphitic carbon. Differential Scanning Calorimeter (DSC) analysis of several samples were performed up to 1200 °C. Thermodynamic modelling was done using FactSage to predict the products of the hematite reduction below 1600 °C. The study showed that PCB residue might be used to partially replace the conventional reductants. The investigations revealed that at temperatures below 1000 °C, PCB reduces hematite to lower forms of iron oxide at a faster rate than that of graphite. The optimal blend contains about 20 wt% PCB residue which has the same reduction degree as graphite. Thermodynamic modelling of iron smelting was also performed using various blends of PCB and coal. The models showed that PCB residue might be used to partially replace the conventional reductants. The study revealed that in iron smelting, the optimal blend contains around 20 wt% PCB residue, with energy savings of 150 kWh/t of ore to achieve the same metal recovery.

Recently, awareness has been raised concerning the need to decrease the total environmental footprint throughout the life cycle of a medicine, including the packaging materials. Aluminum, a highly energy-intensive metal, is widely used in blister packages together with polymers. However, these blister packages suffer from poor recyclability, with the clear majority of waste blister packages (WBPs) disposed of in municipal solid waste, therefore often being incinerated. In the current study, the separation of aluminum from the polymer in WPBs was investigated to make Al available for direct recycling at a secondary Al facility. The characterization of WPBs (ICP-OES, SEM-EDS, and TGA) showed that the investigated fractions consisted of approximately 10-12 wt % of aluminum, with the clear majority of waste blister mass in the polymer fractions, which consisted of two overlapping layers. Moreover, the polymer layer also gave indications of the presence of Cl. WPBs were subjected to electrohydraulic fragmentation,where the effects of the gap between electrodes (10-40 mm), the amount of pulses (50-500 pulses), pulse frequency (2-5 Hz), and discharge voltage (100-180 kV) on the separation process were systematically investigated. It was shown that at optimal conditions (electrode gap of 40 mm, 300 pulses, frequency of 3 Hz, 130 kV of discharge voltage, and 40 g of initial WPB mass), up to 88% of Al (≥99.4% purity) and polymers were recovered from the investigated waste blister samples. The current study contributes toward improving the circular economy of aluminum as well as the reduction in energy consumption by a new application of electrohydraulic fragmentation for pharmaceutical blister packages.

The phase equilibria of the Ag–Ge–Sb–Te system in the part Ag8GeTe6–Ge–GeTe–Sb2Te3 were investigated by the electromotive force (EMF) method. The determined phase relations were used to express the chemical reactions. The potential-forming reactions were performed by applying electrochemical cells (−) C | Ag | Ag2GeS3-glass | D | C (+), where C is graphite, Ag2GeS3-glass is the fast purely Ag+ ions conducting electrolyte, and D is an equilibrium mixture of phases. According to the experimental data on the EMF versus temperature of each electrochemical cells, analytical equations for the Gibbs energies of GeSb8Te13, GeSb6Te10, GeSb4Te7, GeSb2Te4, Ge2Sb2Te5, Ge3Sb2Te6, and Ge4Sb2Te7 compounds were obtained. The thermodynamic properties of silver-saturated tetradymite-like compounds have been calculated for the first time. A good correspondence between experimental values and structure data reported in the literature has been established.

Polythermal sections in the vicinity of the quaternary compounds Ag2FeSnS4 and Ag2FeSn3S8 have been modeled. The mechanism of formation of these quaternary compounds and their thermal stability have been investigated. Measurements of electromotive force allowed calculations of the standard thermodynamic functions ΔG°, ΔH°, and S° of the Ag2FeSnS4 and Ag2FeSn3S8 compounds. Based on calorimetric measurements, the enthalpies of phase transitions of the selected compounds were determined. Furthermore, the heat capacities of both quaternary compounds were estimated by applying different calculation methods. Thermodynamic properties of the quaternary compounds, which are regarded as functional magnetic materials, were analyzed and are discussed in detail.

In this article, oxidation processes of Ag-Bi-Sb-based phases were investigated. Synthesized AgBiS2 and AgSbS2-Sb2S3-Sb samples were thermally analyzed in synthetic air by applying the simultaneous DSC-TGA analysis technique. The oxidation processes at PO₂=0.2 atm and T

Triangulation of the quaternary Ag–Cd–Sn–S system in the Ag2SnS3–SnS–Sn2S3–CdS part below T = 600 K was performed using X-ray diffraction method. The spatial position of the determined four-phase regions regarding the figurative point of silver was used to write forming chemical reactions. The forming reactions were performed by applying electrochemical cells (ECCs): (−) C | Ag | Ag2GeS3 glass | Ag2CdSn3S8, SnS, Sn2S3, CdS | C (+) and (−) C | Ag | Ag2GeS3 glass | Ag2CdSnS4, SnS, Ag2CdSn3S8, CdS | C (+), where C is graphite and Ag2GeS3 glass is the fast purely Ag+ ions conducting electrolyte. The linear dependencies of the EMF of the ECCs on temperature in the range T = (462–500) K were used to calculate the standard thermodynamic values of the Ag2CdSn3S8 and Ag2CdSnS4 phases for the first time.

Due to their high corrosion resistance and thermal stability, Cu-Ni-alloys have essential role in many materials engineering applications. Lead is an alloying element in these alloys although it may also be considered as an impurity in certain cases. In copper rich alloys, lead tends to diffuse into the grain boundaries and weaken the hot-working properties. In addition to alloys design, accurate knowledge of phase relations and solubilities in the ternary Cu-Ni-Pb system has important role in improving the copper and nickel smelting and refining processes. In the present work, an isothermal equilibration technique was used to measure the mutual solubilities of liquid lead and solid CuNi foil in the temperature range 1280–1530 K. The samples were equilibrated and an Inductively Coupled Plasma Atomic Emission Spectrometer (ICP-AES) and an Electron Probe Micro Analyzer (EPMA) were used to quantify the chemical composition of the phases. Selected solubility data obtained in this work were combined with the literature data to obtain a thermodynamic description of the Cu-Ni-Pb ternary liquid and fcc solid solution phases by applying the CALPHAD method. The ternary assessment agrees well with the experimental observations in this work.

Triangulation of the Ag-Hg-Se-I system in the vicinity of quaternary phase Ag4HgSe2I2 was performed by differential thermal analysis, X-ray diffraction and electromotive force (EMF) methods. The spatial position of the phase region Ag4HgSe2I2-Se-HgI2 regarding the figurative point of silver was used to write the chemical reaction of formation of Ag4HgSe2I2. The EMF measurements were carried out by applying an electrochemical cell: (–) C|Ag|Ag2GeS3 glass|Ag4HgSe2I2, HgI2, Se|C (+), where C is graphite and Ag2GeS3 glass is the fast purely Ag+ ions conducting electrolyte. The linear dependence of the EMF of the electrochemical cell on temperature was used to determine the standard thermodynamic values of Ag4HgSe2I2 for the first time.

In this article, current progress in urban mining related to e-waste recycling is reviewed and associated state-of-the-art recycling technologies are evaluated. As sufficient volume of e-waste is a limiting factor for its recycling economy, the need for the establishment of effective e-waste collection mechanisms, particularly for small sized End-of-Life (EoL) devices, is emphasized in terms of the need for effective government policies, increased public awareness, economic incentives, establishing industry-funded co-regulatory agreements, etc. Feasible options for e-waste recycling through pyro- and hydro-metallurgical process routes are reviewed. Deficiencies in e-waste recycling chains are highlighted, and recommendations to improve the current very low collection rate of small sized EoL devices such as mobile phones are made. Optimization of the recovery of the critical metals and energy through different processing options is discussed.

Oxides and intermetallic phases in the platinum-tellurium-oxygen system have been studied. Thermal stabilities, thermodynamics, and structures of the phases reported in the literature, including the conditions under which PtOx form and decompose, have been compiled and critically evaluated. Heat capacities of the binary phases have been estimated, and compared with the scarcely available experimental literature data. The estimated values are generally in agreement with the few available literature data. The intermetallic phase PtTe was synthesized, and thermally analysed by the differential scanning calorimetry and thermogravimetry techniques, under both inert and oxidizing conditions. Based on the calorimetric measurements, the solidus and liquidus temperatures, and enthalpy of melting of PtTe in the phase region PtTe-Pt have been determined. For the first time, the maximum thermal stability of PtTe in an oxidizing atmosphere, close to the partial pressure of oxygen in air, is experimentally determined to be T = (603 ± 1) K, above which it oxidizes to form TeO2 and Pt. Based on experimental observations in this work combined with the literature review, isothermal ternary phase diagram of the Pt-Te-O system is proposed.