Bence Kutus

Phosphate removal from lithium-ion battery (LIB) recycling leachates is essential for improving the recovery efficiency of valuable metals under strongly acidic conditions. Herein, a series of Fe-doped ZIF-8 (Fe-ZIF-8) samples were successfully synthesized via a simple direct precipitation method and systematically investigated for selective phosphate removal from simulated LIB leaching solutions. Among the synthesized materials, the optimized 5% Fe-ZIF-8 sample exhibited a maximum phosphate adsorption capacity of 120.6 mg·g-1 at pH 2 in single-ion phosphate systems and retained 96% phosphate removal efficiency after six adsorption-desorption cycles in complex leachate systems, while maintaining high recoveries of Li, Co, and Ni (88-100%). In contrast, the 30% Fe-ZIF-8 sample exhibited substantially lower adsorption stability and regeneration performance. Low Fe loading promoted highly dispersed and surface-accessible Fe active sites with enhanced structural stability, whereas excessive Fe incorporation induced the formation of FeOOH-rich surface species accompanied by pore blocking, framework degradation, and Fe leaching. To the best of our knowledge, this is the first systematic investigation elucidating the decisive role of Fe loading in governing both adsorption stability and structural evolution of Fe-ZIF-8 under simulated acidic conditions. These findings identify the 5% Fe-ZIF-8 sample as a structurally stable and highly selective adsorbent for efficient phosphate removal and simultaneous metal recovery from LIB recycling processes.

A timely and comprehensive summary of how terahertz (THz) spectroscopy is revolutionizing the study of liquids.

Acid neutralization is an efficient way to lower the solution pH of bauxite residue slurries (generated via the Bayer process) to a level that enables safe handling and further utilization. Tricalcium aluminate hexahydrate (TCA, Ca₃Al₂(OH)₁₂) and its silicate-substituted polymorph, katoite (KAT, Ca₃Al₂(SiO₄)_x(OH)_12-4x), are one of the major sources that contribute to the high alkalinity of residues. Yet, the neutralization chemistry of KAT phases is poorly understood. To this end, we synthesized TCA and KAT and studied their acid-base reactions. We find the as-prepared pseudo-KAT (PKAT) phase to be a poorly substituted TCA with x ≈ 0.05 while containing amorphous calcium silicate hydrate as well as sodium aluminosilicate minor phases. Upon addition of HCl, TCA first transforms to Friedel's salt, a layered double hydroxide hosting Cl^- ions, which is absent for PKAT. Further, the lack of LDH precipitation, closely related to calcium silicate hydrate, gives rise to a lower buffering range (by ∼0.5-1.2 pH units) for PKAT. Another striking consequence of minor silicate phases in PKAT is the ∼17% smaller acid consumption as compared to TCA. In conclusion, amorphous silicates markedly affect both the neutralization mechanism and capacity of tricalcium aluminate hydrates.

Iridium is one of the most frequently employed anode electrocatalysts in CO₂ and CO electrolysis, thanks to its reasonable overpotential for the oxygen evolution reaction (OER) and high stability under operating conditions. The latter has been challenged recently by a handful of studies where destabilization of iridium was observed, which was explained solely by thermodynamics (iridium is unstable at strong alkaline pH and OER potentials). In this study, we demonstrate that liquid CO and CO₂ electrolysis products (such as ethanol and acetate) crossing over to the anode side under long-term operation have a severe effect on the stability of iridium. Its dissolution was studied by both ex-situ inductively coupled plasma mass spectrometry (ICP-MS) and in situ (online ICP-MS) techniques. Based on our electrolysis experiments carried out in a broad pH range (pH = 4-14), ethanol, and its partially oxidized counterpart, acetaldehyde, decreases the stability of the anode catalyst. Ethanol/acetaldehyde oxidation competes with the OER and starts in conjunction with the surface oxidation of the Ir catalyst particles. The oxygenated species are consumed by the alcohol/aldehyde oxidation process, preventing the formation of a passivating surface oxide layer, resulting in an increased iridium dissolution rate.

The conversion of lithium carbonate (Li₂CO₃) with calcium hydroxide (Ca(OH)₂) is a cornerstone industrial process for synthesizing lithium hydroxide (LiOH), a critical precursor for high-performance cathodes in advanced lithium-ion batteries. Achieving a high Li₂CO₃-to-LiOH yield is crucial for efficient industrial processing. However, despite its industrial relevance, the influence of concentration and equilibrium conditions on this conversion reaction remains insufficiently explored. To address this gap, we investigated the conversion reaction by varying the Li₂CO₃ concentration and the Ca(OH)₂:Li₂CO₃ molar ratio. Near-complete conversion yields occur below the maximum concentration threshold of 1.6 mol L^-1 LiOH, while yields diminish above this limit. Sequential reaction experiments confirm that the system adheres to Le Chatelier's principle, and reverse reactions initiated from LiOH and CaCO₃ demonstrate true equilibrium behavior. Furthermore, backward reactions involving distinct CaCO₃ polymorphs reveal different equilibrium states. Notably, the presence of vaterite alongside calcite significantly affects the equilibrium concentration of LiOH, underscoring the role of solid-phase composition in governing reaction thermodynamics. These findings provide a deeper understanding of the causticization mechanism and offer actionable insights for optimizing LiOH production in industrial settings.

A noble metal-free synthesis strategy for pyrimidines via acceptorless dehydrogenative coupling (ADC) was developed. This is enabled by the LaCoO ₃ catalyst, which allows efficient ADC under mild reaction conditions in a green solvent.

Due to the limitations of conventional synthesis and the growing utilization of nanoparticles, recent efforts have shifted to green approaches such as utilizing plant waste extracts. A novel initiative to repurpose household and agricultural green waste for the generation of silver nanoparticles (AgNP) offers a sustainable, low-cost alternative that addresses environmental and economic concerns. In this context, we aimed to evaluate the multi-round recyclability of (CA), green tea (GT), and Virginia creeper (VC) waste for AgNP production, then conduct a comprehensive physicochemical and bioactivity characterization of the nanoparticles. The study was designed to prepare AgNPs using waste from CA, GT, and VC generated by one, two, and three rounds of leftover extractions, then the obtained nanomaterials were characterized by transmission electron microscopy (TEM), ultraviolet-visible (UV-vis) spectroscopy, dynamic light scattering (DLS), and X-ray powder diffraction (XRD). Their toxicity on malignant and nonmalignant human cells was evaluated by viability assays, the antimicrobial performance was assessed on Gram-positive, Gram-negative bacteria and against and by microdilution method. The production of reactive oxygen species (ROS) was examined by a staining method, and the AgNP-related silver ion release was measured by inductively coupled plasma mass spectroscopy. Our findings confirmed successful synthesis of AgNPs utilizing recycled waste materials; nevertheless, the plant type and extraction round influenced AgNP properties to a unique combination of nanoparticle size and stability. All AgNPs showed strong toxicity against human cancer cells, albeit affecting also noncancerous fibroblasts. GT-derived AgNPs exerted potent antibacterial activity, while those by VC had strong antifungal effects. The observed bioactivity correlated with the increasing number of extraction cycles and was the result of enhanced silver ion-releasing capability that culminated in increased ROS levels. These findings demonstrate the viability of multi-round extract recycling for sustainable AgNP synthesis and suggest potential applications in industrial fields such as antimicrobial air filtration systems.

A simple, fast, and easily tunable post-synthetic bromide/iodide exchange method is presented to alter the halide-composition of polycrystalline Cs₃Cu₂Br₅ layers.

Alkaline–surfactant–polymer (ASP) flooding by means of which alkali additives, surfactant and polymer are inserted as the same slug is one of the most favourable worldwide focuses of Chemical Enhanced Oil Recovery (cEOR) research and field trials, due to the individual synergy of the three chemical components. To develop efficient oil recovery chemicals, it is essential to fully understand the mechanism behind ASP flooding. Nonetheless, there are hardly any studies reporting a systematic characterization of the ASP process. Thus, the present paper focuses on modelling this process in a laboratory by the use of an anionic surfactant—sodium dodecyl sulphate (SDS) in alkaline–polymer media—which is composed of a commercial water-soluble polymer (Flopaam AN125SH^®, SNF Floerger, Andrézieux-Bouthéon, France) and alkali compounds (NaOH and Na₂CO₃). The samples were characterized using rheometry, dynamic light scattering (DLS), infrared spectroscopy (IR) and measurement of inferfacial tension (IFT) between the samples and rapeseed oil. In accordance with the experimental results, surprisingly lower IFT values were recorded between the alkaline–polymer solutions and rapeseed oil than the samples which contained SDS. Increasing polymer and sodium chloride concentration caused a decrease (from 0.591 mN/m to 0.0486 mN/m) in IFT between the surfactant containing samples and rapeseed oil. The IR measurements confirmed that the surfactant was not detected in the oil phase in the absence of NaOH and Na₂CO₃. The effects of SDS on the viscosity of the mixtures were also investigated, as viscosity is a considerably important parameter in processes using polymers.