MnO2 nanoparticles were eco-friendly synthesized using Lawsonia inermis extract as a capping and stabilizing agent and then immobilized on the surface of 13X molecular sieve zeolite (MnO2@Z). The green-supported catalyst was tested for the selective oxidation of benzyl alcohol (BzOH) to benzaldehyde (BzDH) in the presence of H2O2 oxidant. The catalyst was characterized using FTIR, XRD, FE-SEM, EDX, TGA, and BET analysis. Many tests were performed to study the effects of reaction time, reaction temperature, amount of catalyst, and H2O2:BzOH ratio on the catalytic performance. The highest activity was achieved after 6 h of reaction at 80 °C, using 250 mg catalyst, and 1.25H2O2: 1BzOH molar ratio. Utilizing the biochemical properties of Lawsonia inermis extract, a highly stable heterogeneous catalyst was developed for the selective oxidation of benzyl alcohol to benzaldehyde. This work demonstrates a heterogeneous catalytic oxidation approach with potential sustainability advantages, including catalyst recyclability and the use of H2O2 as an oxidant. Although the current study demonstrates promising catalytic performance, further optimization of catalyst loading, energy consumption, and recovery procedures, together with comprehensive green chemistry assessments, will be required for future scale-up applications.
Wellbore integrity is central to geological CO2 storage because wells can intersect formations intended to contain injected CO2 and displaced brine. This critical narrative review examines how defects at casing–cement and cement–formation interfaces form, evolve, and contribute to hydraulic communication and potential leakage. Laboratory experiments, field observations, numerical models, and diagnostic studies are compared with attention to what each type of evidence can establish. Cement alteration, structural debonding, measurable fluid movement, and consequential leakage are distinct observations. Interface conductance depends on hydraulic aperture, connectivity, effective stress, thermal and pressure cycling, fluid chemistry, and flow history; mechanical closure or precipitation may restrict pathways, whereas renewed loading or dissolution may preserve or enlarge them. Diagnostic interpretations require method- and well-specific calibration: an undetected anomaly does not establish zero flow. Brine migration, dissolved-CO2 transport, and free-phase CO2 entry have different pressure, capillary, and saturation controls. The proposed interface-to-risk framework links defect evidence, exposure, phase-specific migration, and possible receptor consequences without treating the framework as a calibrated risk model. Priorities include cyclic testing, coupled multiphase characterization, field validation, and laboratory-to-field uncertainty quantification.
Solar drying is a foundational dehydration technique that has evolved significantly from its empirical origins to become a sophisticated engineering discipline. This study presents a comprehensive bibliometric mapping of 50 years of solar drying research (1976–2025) using 4384 documents retrieved from the Web of Science Core Collection. The analysis reveals a steady annual growth rate of 5.42% and a profound shift in research priorities toward the Energy–Food–Health Nexus. While India leads in publication volume (1113 documents), Turkey exhibits the highest research efficiency (60.53 citations per paper). Current trends indicate a move away from open-sun drying toward advanced hybrid systems incorporating Phase Change Materials (PCM), Computational Fluid Dynamics (CFD), and a focus on preserving bioactive compounds, as evidenced by the dominance of SDG 3 (Good Health and Well-being). This review serves as a strategic guideline for future institutional investment and international collaboration to bridge current research gaps in high-solar-potential regions.
Rice husk, a globally abundant rice-milling by-product, is frequently burnt or landfilled and underexploited for valorization into low-cost adsorbents. Converting such agricultural residues into carbonaceous materials supports a circular economy and offers a green alternative to energy- and reagent-intensive activated carbon for removing cationic pollutants. In this work, rice husk was valorized into two chars using muffle-furnace (MFRH) and nitrogen-assisted (NARH) pyrolysis and benchmarked against raw husk (RH) for removal of crystal violet, a model cationic dye. A face-centered central composite design (FCCCD) coupled with response surface method (RSM) was used to model and optimize the process across a pH range (4–10), adsorbent dose (1–9 g·L−1), and CV concentration (10–200 mg·L−1) for each material. Quadratic modelling showed high goodness of fit for all adsorbents (R2 = 0.97–0.99), closely reproducing experimental removals and confirming the suitability of the prediction. Although removal increased with pH and dose for all three materials, the magnitude and curvature of these effects differed markedly between raw and pyrolyzed husk. Raw husk outperformed both chars across most of the design space despite a lower surface area, due to diminished active sites on carbonized material, and the chars exceeded it only under optimized alkaline, high-dose conditions. Numerical optimization identified distinct conditions for each adsorbent, where experimental removals of 96.32% (RH), 98.37% (MFRH), and 99.66% (NARH) were obtained, which are in close agreement with model predictions. These findings show that RSM–CCD can be used to both optimize operating conditions and quantitatively compare rice-husk-derived adsorbents prepared under different pyrolysis conditions.
The growing use of heat pumps in the energy transition increases the importance of selecting refrigerants that simultaneously meet the requirements of energy efficiency, safety and environmental sustainability. The aim of the paper is to analyse the technical, safety and environmental characteristics of modern refrigerants and their role in the transition to more sustainable heating and cooling systems. The research is based on a review of scientific literature, international standards and European Union regulatory documents, with an emphasis on ODP and GWP indicators, refrigerant safety classification, and applicable environmental and safety requirements. The results show that regulatory requirements and climate goals are accelerating the phase-out of high-GWP refrigerants. R32 is identified as a relevant transitional solution, while R290 stands out because of its very low environmental impact and good thermodynamic properties, although it requires enhanced safety measures due to its flammability. HFO fluids provide low-GWP options for selected applications, although their long-term environmental and regulatory status requires further assessment. It is concluded that the assessment of the sustainability of refrigeration systems must include energy, safety, environmental and regulatory criteria, as well as life cycle indicators such as TEWI and LCCP.
