Sorin Marius Avramescu

This study investigates the efficiency of green corrosion inhibitors derived from spent coffee grounds (SCGs) for OL 37 carbon steel in 0.5 M H₂SO₄ and 1 M HCl environments. The aqueous extracts, labeled K1 and K2, were obtained through specialized extraction techniques and characterized by HPLC. Their protective performance was investigated using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). FT-IR spectroscopy and SEM-EDX analysis confirmed the presence of a protective inhibitor film on the OL 37 surface, attributed to the adsorption of organic molecules from the SCGs extract (K1 and K2). The adsorption behavior followed the Langmuir isotherm, with high adsorption constants and standard free energy values (ΔG°_ads), indicating a mixed-mode adsorption mechanism. Furthermore, the negative Gibbs free energy values of adsorption confirm the spontaneity of the adsorption process. Thermodynamic studies conducted between 293 K and 333 K demonstrated the temperature dependence of the inhibition process. Results showed that at a concentration of 800 ppm and 1000 ppm, both inhibitors exhibited high efficiency, reaching 96% for K1 and 95% for K2.

This study focuses on the evaluation of eco-friendly corrosion inhibitors derived from extracts of Rhus typhina L. leaves, collected in August during the summer season, on OLC45 metal surfaces in a 0.5 M H₂SO₄ corrosive environment. The extracts were obtained using the microwave extraction technique and characterized by HPLC. The protective properties of OLC45 coated with LESRT (leaf extract collected in summer from Rhus typhina L.) were examined by potentiostatic and potentiodynamic polarization procedures and electrochemical impedance spectroscopy (EIS) in 0.5 M H₂SO₄. The application of the Langmuir isotherm revealed high values of the adsorption constant and standard free energies (ΔG°_ads), suggesting a possible mixed adsorption process with an increased tendency toward chemisorption. The influence of temperature on the electrochemical behavior of OLC45 samples in H₂SO₄, both in the absence and presence of two extracts derived from Rhus typhina leaves at a concentration of 1000 ppm, was investigated over the temperature range of 293–333 K. A comparison of the two inhibitors’ effectiveness revealed high inhibitory efficiency, up to 91% at 1000 ppm LESRT₁ (methanol/double-distilled water (50%:50%, v/v)) and 92% for LESRT₂ (ethanol/double-distilled water (50%:50%, v/v)) at 1000 ppm LESRT₂.

The evaluation of local natural resources and their sustainable use as alternatives for allopathic medicines or phytosanitary treatments based on chemical syntheses, is a priority of research worldwide. The aim of this research was to obtain Prunella vulgaris L. extracts through modern, ecofriendly methods, to evaluate their ability to biosynthesize silver nanoparticles (AgNPs), as well as the physicochemical characterization of AgNPs to determine the polyphenol content, antioxidant and antimicrobial activity as well as phytotoxicity of the resulting nanoformulations, through in vitro tests. Microscopic analysis of the extracts showed the spherical shape of AgNPs, especially in the biosynthesized samples from the microwave extracts. The sizes of the nanoparticles ranged between 8.64 and 13.84 nm. Microwave-assisted extraction favored the procurement of crude extracts from P. vulgaris herba with a high content of polyphenols (77.98 mg GAE/g dw⁻¹) and a correlated antioxidant activity. Rosmarinic acid was identified in all analyzed samples (61.8287–1.0031 mg/L). The extracts obtained using microwaves, in which the nanoparticles were also biosynthesized using microwaves, had the best antifungal activity against Fusarium oxysporum MUCL 791. The combination of antifungal properties with those of seedling growth stimulation are of major importance in plant culture, with the early stages of their life cycle requiring constant attention.

Enhancing bioactive compounds with antioxidant activities has always been a pursuit of growers in the hydroponic production of lettuce in greenhouses with artificial lighting. Light-Emitting Diode (LED) lighting represents an effective lighting strategy that promotes the accumulation of bioactive compounds in lettuce by reducing dark periods under unfavorable meteorological conditions and extending the photosynthetic duration. In this study, the accumulation of bioactive compounds and their antioxidant activities, using lettuce-adapted growth technologies such as elevated oxygen concentration and elevated oxygen combined with LED red-blue light, were investigated. These technologies were compared to the control, which consisted of the natural oxygen concentration, in a controlled hydroponic system, for the two lettuce cultivars, Carmesi and Lugano. Our results demonstrate that lettuce grown under elevated oxygen combined with LED lighting exhibited increases of up to 48% in total phenolic content and up to 87% in total flavonoid content, depending on cultivar and growing season, compared to control growth technology. The highest antioxidant capacity was recorded under the EOC+LED growth technology, as confirmed by DPPH, FRAP, and CUPRAC assays. This study proposes an effective growth strategy for hydroponic lettuce cultivation that enhances bioactive compound accumulation and provides theoretical and technical guidance for energy-efficient greenhouse production.

Polymers have long been central to modern materials science, but their durability has also made them major contributors to environmental pollution. A new generation of bio-based and nanostructured polymers is now reshaping this field, offering materials that are functional, reversible, and sustainable. This review examines their role across three interconnected domains: cultural heritage conservation, the protection of medicinal and aromatic plants (MAPs), and environmental sustainability. In heritage science, polymers are moving away from synthetic resins toward renewable systems such as chitosan, nanocellulose, and PLA, which provide stability while remaining reversible and compatible with delicate substrates. In agriculture, biodegradable coatings, controlled-release carriers, and edible films are improving MAP protection, extending shelf life, and reducing reliance on synthetic pesticides. In environmental applications, polymers are being reinvented as solutions rather than problems—through degradable mulches, functional hydrogels, and nanocomposites that clean soils and waters within a circular economy framework. Looking across these domains reveals strong synergies. The same principles—biodegradability, multifunctionality, and responsiveness—apply in each context, turning polymers from passive barriers into intelligent, adaptive systems. Their future success will depend not only on chemistry but also on life-cycle design, policy alignment, and public trust, making polymers key enablers of sustainability.

This study evaluates the corrosion-inhibiting effects of the methanolic (P₁) and the hydroalcoholic (P₂) extracts of the Rhus typhina L. leaves on carbon steel (OL37) in 1 M HCl. Extracts were prepared with microwave-assisted extraction and characterized using HPLC and LC-MS. Electrochemical methods (OCP, EIS, PDP) and surface analyses (SEM, EDX) assessed the performance of both extracts. The results showed that the P₁ and P₂ extracts significantly reduced corrosion rates by forming protective layers on the metal surface, with inhibition efficiencies exceeding 90%, at 1000 ppm concentration, for P₁ (93%), for P₂ at 800 ppm (91%) and 1000 ppm (94%). The P₂ extract demonstrated superior long-term performance, maintaining protection after 96 h of immersion. The extracts function as mixed-type inhibitors, affecting both anodic and cathodic reactions, with physicochemical adsorption demonstrated by the Langmuir isotherm. Overall, the Rhus typhina leaf extracts, particularly the P₂ extract, offer a promising, eco-friendly approach to corrosion prevention in acidic environments.

This review examines recent advances in corrosion inhibitor technologies, with a focus on sustainable and environmentally friendly solutions that address both industrial efficiency and environmental safety. Corrosion is a ubiquitous problem, contributing to massive economic losses globally, with costs estimated between 1 and 5% of GDP in different countries. Traditional inorganic corrosion inhibitors, while effective, are often based on toxic compounds, necessitating the development of more environmentally friendly and non-toxic alternatives. The present work highlights innovative eco-friendly corrosion inhibitors derived from natural sources, including plant extracts and oils, biopolymers, etc., being biodegradable substances that provide effective corrosion resistance with minimal environmental impact. In addition, this review explores organic–inorganic hybrid inhibitors and nanotechnology-enhanced coatings that demonstrate improved efficiency, durability, and adaptability across industries. Key considerations, such as application techniques, mechanisms of action, and the impact of environmental factors on inhibitor performance, are discussed. This comprehensive presentation aims to contribute to updating the data on the development of advanced corrosion inhibitors capable of meeting the requirements of modern industries while promoting sustainable and safe practices in corrosion management.

Metal nanoparticle phytosynthesis has become, in recent decades, one of the most promising alternatives for the development of nanomaterials using “green chemistry” methods. The present work describes, for the first time in the literature, the phytosynthesis of silver nanoparticles (AgNPs) using extracts obtained by two methods using the aerial parts of Marrubium vulgare L. The extracts (obtained by classical temperature extraction and microwave-assisted extraction) were characterized in terms of total phenolics content and by HPLC analysis, while the phytosynthesis process was confirmed using X-ray diffraction and transmission electron microscopy, the results suggesting that the classical method led to the obtaining of smaller-dimension AgNPs (average diameter under 15 nm by TEM). In terms of biological properties, the study confirmed that AgNPs as well as the M. vulgare crude extracts reduced the viability of human gingival fibroblasts in a concentration- and time-dependent manner, with microwave-assisted extracts having the more pronounced effects. Additionally, the study unveiled that AgNPs transiently increased nitric oxide levels which then decreased over time, thus offering valuable insights into their potential therapeutic use and safety profile.

The present work aims to study the possibilities of developing silver nanoparticles using natural extracts of grape pomace wastes originating from the native variety of Fetească Neagră 6 Șt. This study focused on investigating the influence of grape pomace extract obtained by two different extraction methods (classical temperature extraction and microwave-assisted extraction) in the phytosynthesis process of metal nanoparticles. The total phenolic content of the extracts was assessed using the spectrophotometric method with the Folin–Ciocâlteu reagent, while the identification and quantification of specific components were conducted through high-performance liquid chromatography with a diode array detector (HPLC-DAD). The obtained nanoparticles were characterized by UV–Vis absorption spectroscopy, X-ray diffraction (XRD), and transmission electron microscopy (TEM), along with assessing their antioxidant and antimicrobial properties against Gram-positive bacteria. The data collected from the experiments indicated that the nanoparticles were formed in a relatively short period of time (96 h) and, for the experimental variant involving the use of a 1:1 ratio (v/v, grape pomace extract: silver nitrate) for the nanoparticle phytosynthesis, the smallest crystallite sizes (from X-ray diffraction—4.58 nm and 5.14 nm) as well as spherical or semispherical nanoparticles with the lowest average diameters were obtained (19.99–23 nm, from TEM analysis). The phytosynthesis process was shown to enhance the antioxidant properties (determined using the DPPH assay) and the antimicrobial potential (tested against Gram-positive strains) of the nanoparticles, as evidenced by comparing their properties with those of the parent extracts; at the same time, the nanoparticles exhibited a selectivity in action, being active against the Staphylococcus aureus strain while presenting no antimicrobial potential against the Enterococcus faecalis strain.