A sustainable circular pathway was developed for poly(ethylene terephthalate) (PET) nanocomposites through a catalyst-driven polymerization and depolymerization process. In this study, calcium dodecylbenzene sulfonate with n-butyl alcohol modified ZnAl layered double hydroxides (LDHs) were utilized as bifunctional catalysts to synthesize highly exfoliated PET/LDH nanocomposites via in situ polycondensation of bis(2-hydroxyethyl) terephthalate (BHET). The organic modification of LDHs expanded interlayer spacing, improved interfacial compatibility, and promoted uniform dispersion, leading to enhanced mechanical, thermal, and barrier properties. In the second stage, the pristine LDH catalyst efficiently depolymerized the prepared PET/LDH nanocomposites back into BHET through glycolysis, completing a closed-loop BHET-to-BHET cycle. This integrated strategy demonstrates the reversible catalytic functionality of LDHs in both polymerization and depolymerization, reducing metal contamination and energy demand. The proposed approach represents a sustainable route for designing recyclable high-performance PET nanocomposites aligned with the principles of green chemistry and circular material systems.

This work used activated carbon material obtained by chemical activation of abundantly available agricultural sunflower waste residues to remove metol (4-(methylamino) phenol sulfate, MTL) from aqueous solutions. The adsorbent structure was characterized using SEM-EDS and FT-IR spectroscopy. A modified screen-printed carbon electrode (SPCE) with gold nanoparticles synthesized using the Laser Ablation Synthesis in Solution (LASIS) method was used to detect MTL. The successful LASIS formation of gold nanoparticles was confirmed by the specific dark burgundy–red color. TEM measurements showed uniform pseudo-spherical particles with an average diameter of 7.9 ± 0.2 nm. The modified electrode showed improved electrochemical activity, which was confirmed by comparing it with an unmodified electrode using cyclic voltammetry and electrochemical impedance spectroscopy. The modified electrode was subsequently used to optimize the MTL detection conditions. UV–Vis spectroscopy was used to optimize the adsorption conditions, with the optimal values for pH and contact time found to be 8 and 120 min, respectively. The electrochemical detection of MTL was performed using differential pulse voltammetry, and the linear calibration range was established for concentrations ranging from 0.73–49.35 µM. The obtained limits of detection (LOD) and quantification (LOQ) were 0.06 µM and 0.2 µM, respectively. The efficiency of MTL removal was 100% after a contact time of 1 min and remained at 100% after 120 min.

This study investigates amorphous anodized porous TiO2 (a-TiO2) as a substrate for iridium-based oxygen evolution catalysts. The substrates were prepared via anodization of Ti foil in a glycerol-based solution for 15 min @ 60 V. Nickel was subsequently electrodeposited to act both as a conductive and sacrificial layer for the galvanic deposition of iridium from an Ir(IV) chloro-complex solution. Electrochemical anodization resulted in a uniform IrOx layer on the a-TiO2 substrate, featuring Ir aggregates ~250 nm in size and an Ir:Ni atomic ratio of ca. 7, as determined by EDS analysis. The quantity of Ni determined by ICP-MS bulk analysis indicated that Ni resided also within the porous matrix. Varying the Ni deposition charge density (qNi) revealed that an intermediate loading (1463 mC cm−2) provided the best balance between Ir accessibility during the galvanic replacement step and electronic continuity. The optimized IrOx/Ir-Ni/a-TiO2 electrode achieved excellent OER performance (η = 344 mV @ 10 mA cm−2; 1.68 mA μgIr−1 @ η = 300 mV) at an ultra-low Ir loading of 2.15 μgIr cm−2 and demonstrated good short-term stability, with only a 20 mV potential increase over 4 h of continuous operation at 5.5 mA cm−2. Overall, this strategy offers a scalable pathway for producing efficient OER electrodes with minimal noble metal loading.

The old spectral displacement method can be suitably revitalized for a didactic experimental approach to fundamental concepts of supramolecular chemistry and to the study of complex equilibria in general. In particular, the case of the β-cyclodextrin/phenolphthalein/adamantane ternary system has been taken into account as a viable and impressive example due to the remarkable color changes that can be observed when performing the experiments. A new method for data regression analysis is proposed, with a smart trick able to overcome the mathematical difficulties arising whenever multiple equilibria must be considered. Hence, some aspects of the reliability of fitting procedures are discussed.

Mercury (Hg2+) contamination in water systems poses a severe environmental and health hazard due to its high toxicity and bioaccumulation potential. In this study, a novel adsorbent was developed by sequentially modifying kaolin via acid–base treatment, titanium dioxide (TiO2) incorporation, and 3-aminopropyltriethoxysilane (APTES) grafting. Batch adsorption experiments revealed that the fully modified kaolin (TiO2-loaded and APTES grafted) exhibited the highest adsorption capacity (25.6 mg/g) compared to the acid–base-treated (5.8 mg/g) and TiO2-loaded (17.7 mg/g) kaolin. Under optimal conditions (75 mg adsorbent dosage; 70 mg/L Hg2+; pH 5), the fully modified kaolin maintained its performance even in the presence of varying ionic strengths, natural organic matter, and competing metal ions. Adsorption kinetics followed a pseudo-second-order model, and the equilibrium data were well fitted by the Langmuir isotherm. Antibacterial activity assay revealed that the TiO2-loaded kaolin effectively inhibited S. aureus (minimum inhibitory concentration = 2.5 mg/mL) and showed moderate activity against E. coli (BL21) (minimum inhibitory concentration = 5 mg/mL). However, antibacterial activity decreased after amine functionalization, indicating a compromise between enhancing adsorption capacity and preserving antibacterial functionality. This study presents a promising cost-efficient approach for the simultaneous removal of Hg2+ ions from water matrices and inhibiting bacterial growth, aligning with SDG 6 (Clean Water and Sanitation).

Deep eutectic solvents (DES) were selected for the extraction of anthocyanins from red grape skins as an efficient and environmentally friendly solvent alternative to traditional mixtures based on methanol. In silico studies (COSMO-RS) were employed as screening tools to identify the most suitable options, significantly reducing the chemical space of potential DES to be studied. A total of 30,132 DES combinations were assessed. The DESs selected were polyalcohols (ethyleneglycol, glycerol, 1,2-propanediol, and 1,6-hexanediol) and carboxylic acids (citric, oxalic, malic, and lactic acid) as hydrogen bond donors (HBD) and choline chloride, betaine, or salts (potassium carbonate, sodium acetate, and propionate), as hydrogen bond acceptors (HBA). Choline chloride:glycerol and choline chloride:oxaclic acic were selected as solvents to optimize time, temperature, and water content in ultrasound- and microwave-assisted extraction of anthocyanins. In both cases, around 20 wt% of water was found to be the optimum to maximize the extractions, whereas extraction time and temperature depended on the type of anthocyanin. The amount of malvidin-3-O-glucoside extracted by microwave-assisted extraction with choline chloride: oxalic acid was 172 ± 7 mg/kg and 119.5 ± 0.5 mg/kg by ultrasound-assisted extraction with choline chloride: glycerol, which means an increase in performance of, respectively, 64 and a 13% compared to the traditional method.

This interdisciplinary study explores the potential of bioactive compounds from Aronia melanocarpa pomace, a juice industry by-product. The ethanol extract of the pomace was analyzed using HPLC, revealing key polyphenolic acids and anthocyanins. The extract exhibited outstanding antioxidant activity (100% as measured by the ABTS assay and 98.23% as measured by the DPPH assay) and >99% antibacterial efficacy against E. coli and S. aureus. This bioactive extract was utilized in a one-step process to dye and functionalize textiles (wool, silk, cellulose acetate, cotton, and viscose), with cotton and viscose suited for colored disposable bioactive textiles, particularly protective healthcare textiles, due to strong antioxidant (>97% as measured by the ABTS assay and >76% as measured by the DPPH assay) and antibacterial (>75% for E. coli and >80% for S. aureus) properties. The aronia pomace extract was also incorporated into newly synthesized starch/gelatin hydrogels with a compression modulus of 0.041–0.127 MPa and equilibrium swelling ratios of 3.33–4.26 g/g. Functionalized hydrogels demonstrated over 99% ABTS antioxidant activity, while the antibacterial efficacy against E. coli and S. aureus exceeded 70% and 97%, respectively. These properties, combined with the hydrogels’ ability to control the release of extract compounds, make them adequate for wound care applications. The extract’s effectiveness as a green inhibitor for carbon steel, with inhibition efficiency surpassing 94% at a concentration of aronia pomace extract of 100 ppm, was confirmed by electrochemical methods. Moreover, the extract predominantly retards the cathodic reaction. The current research represents the first exploration of alternative and green sustainable technologies for developing novel products based on aronia pomace extract.

The burning of coal in thermal power plants throughout Serbia produces significant amounts of industrial waste, primarily in the form of fly ash, boiler ash, and slag. Given their annual production, availability, and fine grain structure, it is necessary that sustainable strategies are developed for their reuse, instead of depositing them directly in landfills. In this research, the possibility of using fly ash, slag, and diatomaceous earth as raw materials for the synthesis of geopolymers at low temperatures was examined, in order to replace cement in construction materials, with the aim of reducing carbon dioxide emissions. Special emphasis was put on the effect of addition of organic macromolecules—polyvinyl alcohol (PVA), chitosan, and starch—upon the structure and mechanical properties of the obtained materials. In addition, the behavior of the materials with regard to the leaching of heavy metals in different environmental conditions was examined. Chemometric methods of multivariate analysis were used to examine the correlations between the obtained physical–chemical parameters, while the dependence of mechanical properties on the composition of the raw mixture was analyzed using the Mixture Design of Experiments method. The results obtained indicate that the examined waste materials have potential to be used as an environmentally friendly alternative to cement. The addition of PVA and chitosan had a positive effect on the mechanical properties of the geopolymers, with the highest strength achieved in formulations based solely on fly ash, containing 2.5% PVA, which reached 12.6 MPa. It was also shown that the addition of 30% diatomaceous earth increases the density and compressive strength of the material, while reducing the number of microcracks present in its structure, with a compressive strength of 13 MPa.

Catalytic upgrading of bioethanol via a C–C coupling reaction is a sustainable method of producing 1-butanol, a high-performance biofuel. This reaction was studied using a flow-through microreactor system with Pd/MgO-Al2O3 and bimetallic Pd-Cu/MgO-Al2O3 mixed oxide-based catalysts in a H2 carrier gas at a pressure of 21 bar and temperatures ranging from 200 to 350 °C. The effect of the metal promoter(s) on the hydrogen transfer reaction steps in the overall reaction was investigated. The palladium promoter significantly improved the activity and butanol selectivity across the entire temperature range. However, the yield of liquid products decreased significantly at temperatures higher than 250 °C, primarily because the decarbonylation side reaction of the acetaldehyde intermediate accelerated. The promoting effect of Pd was most beneficial below 250 °C because the decarbonylation reaction was inhibited by the reversible poisoning effect of CO on multiple Pd sites responsible for decarbonylation. Diluting the Pd phase with Cu increased liquid yields due to gradually decreasing decarbonylation activity. However, the dehydrogenation–hydrogenation activity decreased as well, as did the promoting effect on the corresponding reaction steps in the coupling reaction. Additionally, the product distribution changed dramatically, decreasing 1-butanol selectivity, because metallic Cu can catalyze the formation of ethyl acetate and ketone products.

Ammonia, widely regarded as the “hydrogen carrier of the future,” offers high hydrogen content, ease of production, and a well-established infrastructure for handling and transportation globally. Meanwhile, ammonia cracking requires a heat supply at high temperatures, and induction heating provides efficient, precise, and rapid heating to conductive materials of different shapes and sizes. Therefore, this work presents a proof of concept for ammonia cracking using induction heating with three different reactor configurations: (1) a 3D metal workpiece; (2) a 3D metal workpiece and Ni/Al2O3 catalyst; and (3) only Ni/Al2O3 catalyst. The performance of the inductively heated reactor is also compared to an electric furnace. The results showed that the reactor with the workpiece and the catalyst required 97 W to reach 650 °C, being the most efficient in terms of power usage when compared to the workpiece alone and the electric tube furnace, which required 39% and 132% more, respectively; the least efficient configuration is with just the catalyst, needing 138 W to reach just 116 °C. Overall, the introduction of the 3D workpiece allowed for fast and uniform conversion and heating within the reactor, enabling efficient and dynamic process control when applying induction heating to chemical reactors.