Table of Contents
- Utilizing waste lithium-ion batteries for the production of graphite-carbon nanotube composites as oxygen electrocatalysts in zinc-air batteries
- Recent advances in asymmetric synthesis via cyclopropanol intermediates
- Characterization and changes in the thermal behavior of the phosphorite sample from Toolse deposit (Estonia) along the drill-core
- CO2 transformed into highly active catalysts for the oxygen reduction reaction via low-temperature molten salt electrolysis
- Mechanochemically driven covalent self-assembly of a chiral mono-biotinylated hemicucurbit[8]uril
- Degradation of imidazolium-based ionic liquids by UV photolysis and pulsed corona discharge: The effect of persulfates addition
- Exploring Pathways to Circular Economy Practices in Estonian Manufacturing SMEs: A Fuzzy-Set QCA Approach on Stakeholder Pressure and Collaboration
- Role of Stakeholder Engagement in Sustainable Development in Estonian Small and Medium-Sized Enterprises
- Kinetics of Estonian Phosphate Rock Dissolution in Hydrochloric Acid
Utilizing waste lithium-ion batteries for the production of graphite-carbon nanotube composites as oxygen electrocatalysts in zinc-air batteries
Praats, Reio; Sainio, Jani; Vikberg, Milla; Klemettinen, Lassi; Wilson, Benjamin P.; Lundstrom, Mari; Kruusenberg, Ivar; Liivand, Kerli
The growing global demand for energy has increased the use of lithium-ion batteries (LIBs), leading to a rising volume of end-of-life batteries. Recycling has become essential to recover valuable resources, but graphite from the anode is often lost. This study presents a method to valorize black mass leach residue, a waste from LIB recycling, mainly composed of graphite and minor metal residues. The residue is converted into a bifunctional oxygen electrocatalyst by doping with nitrogen and incorporating carbon nanotubes to improve surface area and conductivity. This catalyst enhances oxygen reduction and evolution reactions in zinc–air batteries (ZAB). The best catalyst showed a power density of 97 mW cm−2 and stable performance for 70 hours in ZAB charge–discharge cycling. This research advances the efficient use of LIB recycling waste, supporting closed-loop materials circularity.
Recent advances in asymmetric synthesis via cyclopropanol intermediates
Laktsevich-Iskryk, Marharyta; Hurski, Alaksiej; Ošeka, Maksim; Kananovich, Dzmitry
Cyclopropanols have attracted significant attention in organic synthesis as versatile three-carbon synthons, as this readily available class of donor-activated cyclopropanes undergoes miscellaneous transformations, either via ring-opening or with retention of the cyclopropane ring. This review summarizes stereoselective and stereoretentive transformations suitable for asymmetric synthesis. The utility of cyclopropanols is discussed for two main strategies: substrate-controlled transformations using enantiomerically enriched cyclopropanol intermediates through a traditional approach, and the use of nonchiral or racemic cyclopropanols, where asymmetric induction is achieved through a chiral catalyst, representing a direction that has recently emerged.
Characterization and changes in the thermal behavior of the phosphorite sample from Toolse deposit (Estonia) along the drill-core
Kaljuvee, Tiit; Tonsuaadu, Kaia; Kallaste, Toivo; Graul, Sophie; Hints, Rutt; Kivimae, Eliise-Koidula; Petkova, Vilma; Trikkel, Andres
The thermal behavior of shelly phosphorite ore from the Toolse deposit (drill-core PH014B, depth 21.1–26.7 m, sub-sampled at 0.1 m intervals) was studied. The primary phosphorus-bearing mineral, fluorcarbonate apatite (francolite), partially transformed into fluorhydroxyl apatite over time. Thermoanalytical experiments using a Setaram Labsys Evo 1600 with a Pfeiffer Omnistar Mass Spectrometer were conducted under non-isothermal conditions (10 °C min−1, up to 1200 °C, 79% Ar, 21% O2). XRD, FTIR, and XRF analyses determined mineralogical and chemical composition. Apatite and quartz were dominant, with apatite content decreasing upwards and quartz increasing, reflecting sediment formation changes. Pyrite and clay minerals were common, while K-feldspar occurred mostly in upper layers. Dolomite and calcite were present throughout, with dolomite especially abundant in the deepest layers (26.3–26.7 m). Organic carbon was concentrated in upper layers (21.1–23.0 m) with black shale interbeds. Results showed a strong correlation between thermal behavior and mineralogical and chemical composition changes.
CO2 transformed into highly active catalysts for the oxygen reduction reaction via low-temperature molten salt electrolysis
Remmel, Anna-Liis; Ratso, Sander; Liivand, Kerli; Danilson, Mati; Kaare, Katlin; Mikli, Valdek; Kruusenberg, Ivar
The implementation of a technology capable of capturing and converting CO2 into valuable products is one of the key requirements for limiting the effects of our carbon-intensive industries. At the same time, future CO2 emissions need to be reduced to combat climate change, meaning that new devices capable of storing and converting energy without CO2 emissions have to be adopted widely. In this work, we demonstrate catalysts made directly from CO2 for fuel cells and zinc-air batteries. The molten salt electrolysis process is used to electrodeposit solid carbon from CO2 in two mixtures, a known eutectic mixture of Li2CO3, Na2CO3, K2CO3 and a new mixture containing 0.1 mol of LiOH in addition. The effects of the electrolyte towards the final carbon product and its electrocatalytic activity are analysed using the rotating disk electrode method, X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy. The porosity of the materials is described by N2 adsorption and the best performing catalyst is compared to the activity of a commercial 20 wt% PtRu/C material in a zinc-air battery.
Mechanochemically driven covalent self-assembly of a chiral mono-biotinylated hemicucurbit[8]uril
Suut-Tuule, Elina; Jarg, Tatsiana; Tikker, Priit; Lootus, Ketren-Marlein; Martõnova, Jevgenija; Reitalu, Rauno; Ustrnul, Lukas; Ward, Jas S.; Rjabovs, Vitalijs; Shubin, Kirill; Nallaparaju, Jagadeesh V.; Vendelin, Marko; Preis, Sergei; Öeren, Mario; Rissanen, Kari; Kananovich, Dzmitry; Aav, Riina
Solution-based synthesis of complex molecules with high efficiency leverages supramolecular control over covalent bond formation. Herein, we present the mechanosynthesis of chiral mono-biotinylated hemicucurbit[8]urils (mixHC[8]s) via the condensation of D-biotin, (R,R)- or (S,S)-cyclohexa-1,2-diylurea, and paraformaldehyde. The selectivity of self-assembly is enhanced through mechanochemistry and by fostering non-covalent interactions, achieved by eliminating solvents and conducting the reaction in the solid state. Rigorous analysis of intermediates reveals key processes and chemical parameters influencing dynamic covalent chemistry. The library of ca. 50,000 theoretically predicted intermediates and products leads to covalent self-assembly of chiral hemicucurbiturils. Mechanochemically prepared diastereomeric (−)- and (+)-mixHC[8]s are suitable for anion binding and derivatization. Immobilization of the macrocycles on aminated silica produces a functional material capable of selective capture of anions, as demonstrated by efficient perchlorate removal from a spiked mineral matrix.
Degradation of imidazolium-based ionic liquids by UV photolysis and pulsed corona discharge: The effect of persulfates addition
Nikitin, D.; Preis, S.; Dulova, N.
Ionic liquids (ILs), salts with exceptional properties, pose potential hazards due to high aqueous solubility and toxicity. Many ILs resist conventional wastewater treatment, necessitating alternative solutions. This study investigated the degradation of imidazolium-based ILs—[Emim][Cl], [Omim][Cl], and [Emim][Br]—using pulsed corona discharge (PCD) and UV photolysis combined with persulfates (PMS and PDS) under varying conditions. Results showed complete IL degradation, with rates influenced by alkyl chain length and anion type ([Emim][Cl] > [Omim][Cl] > [Emim][Br]). UV/oxidant combinations strongly activated persulfates, while PCD’s effect varied with oxidant concentration. Unassisted PCD and UV/PDS had comparable energy efficiencies for certain ILs, with UV/PDS outperforming PCD for [Omim][Cl].
Exploring Pathways to Circular Economy Practices in Estonian Manufacturing SMEs: A Fuzzy-Set QCA Approach on Stakeholder Pressure and Collaboration
Ahmadov, Tarlan; Gerstlberger, Wolfgang; Rahman, Khusbu
In response to global imperatives for sustainability, particularly within the framework of the circular economy (CE), this study examines the adoption of CE practices among manufacturing Small and Medium Enterprises (SMEs) in Estonia. Based on a sample of 78 responses using complete case analysis, this research aims to uncover the configurations of stakeholder pressure (business and social) and collaboration (supply and demand-side) pathways that facilitate successful CE adoption. Drawing on Fuzzy-set Qualitative Comparative Analysis (fsQCA) and Configurational Theory, the study explores how interactions among these factors influence the adoption of CE practices. The empirical investigation, grounded in the Estonian context, reveals three key pathways driving CE adoption: demand-side collaboration, social pressure without direct business pressure, and the combination of business pressure with supply-side collaboration. The findings not only contribute theoretically by advancing configurational approaches in CE research but also offer practical implications for SME managers seeking to adopt CE practice.
Role of Stakeholder Engagement in Sustainable Development in Estonian Small and Medium-Sized Enterprises
Ahmadov, Tarlan; Ulp, Siret; Gerstlberger, Wolfgang
This study examines the role of stakeholders in promoting the sustainable development of SMEs, with focusing on environmental sustainability and innovation. Specifically, it investigates the role of customers, local governments, competitors, and non-governmental organizations (NGOs). This study employs a qualitative approach using 10 semi-structured interviews to collect data from SMEs operating in Estonia. These findings suggest that stakeholder engagement is crucial for promoting the sustainable development of SMEs. While the government may not play an active role in promoting sustainability, NGOs, consumers, and competitors can all play an important role in supporting SMEs' sustainability efforts. These findings provide insights into the various stakeholders that SMEs should consider in their sustainability strategies and highlight the importance of collaboration and engagement with stakeholders to achieve sustainable development goals. The study contributes to the understanding of the role of stakeholders in promoting sustainable development in SMEs, specifically in the context of Estonia.
Kinetics of Estonian Phosphate Rock Dissolution in Hydrochloric Acid
Azeez, Ruhany Sheherazad; Tõnsuaadu, Kaia; Kaljuvee, Tiit; Trikkel, Andres
The dissolution kinetics of Estonian phosphate rock in hydrochloric acid were studied, focusing on particle size, acid concentration (0.5–1.5 M), and reaction mechanisms. At 2.1 moles of HCl per mole of calcium for 60 minutes, phosphorus solubility reached 94%–100% for fine samples and 82%–99% for coarse samples. Steady-state pH was achieved faster with higher acid concentrations and smaller particle sizes. CaF2 precipitation occurred more rapidly at acid concentrations ≥1 M. SEM analysis revealed etch pits on insoluble particles, while XPS and EDX confirmed incongruent dissolution and CaF2 formation on particle surfaces. Kinetic analysis using the shrinking core model indicated chemical reaction, diffusion, and interfacial transfer as governing mechanisms, sequentially for coarse particles and simultaneously for fine particles.