A kinetic and mechanistic investigation of the alcoholysis of phenyl isocyanate using 1-propanol as the alcohol was undertaken. A molecular mechanism of urethane formation in both alcohol and isocyanate excess is explored using a combination of an accurate fourth generation Gaussian thermochemistry (G4MP2) with the Solvent Model Density (SMD) implicit solvent model. These mechanisms were analyzed from an energetic point of view. According to the newly proposed two-step mechanism for isocyanate excess, allophanate is an intermediate towards urethane formation via six-centered transition state (TS) with a reaction barrier of 62.6 kJ/mol in the THF model. In the next step, synchronous 1,3-H shift between the nitrogens of allophanate and the cleavage of the C–N bond resulted in the release of the isocyanate and the formation of a urethane bond via a low-lying TS with 49.0 kJ/mol energy relative to the reactants. Arrhenius activation energies of the stoichiometric, alcohol excess and the isocyanate excess reactions were experimentally determined by means of HPLC technique. The activation energies for both the alcohol (measured in our recent work) and the isocyanate excess reactions were lower compared to that of the stoichiometric ratio, in agreement with the theoretical calculations.

Kinetic parameters of phenyl isocyanate–monoalcohol reactions has been studied using a microreactor system. The monoalcohol components were propan-1-ol, butan-1-ol, propan-2-ol and butan-2-ol. The reactions were conducted in alcohol/THF mixed solvent under pseudo-first-order circumstances at various temperatures. The reaction mixtures were analyzed by off-line HPLC. Reaction rate constants and apparent activation energies have been determined with good precision. The reaction rate constants were higher for the primary alcohols than for the secondary alcohols. Higher apparent activation energy was found for the secondary alcohols compared to the primary ones. The applied technique provides a simple way to study the effects of various factors (e.g. structure of the isocyanate and the alcohol, temperature, solvents, concentration of reagents, catalysis) on the kinetics of the isocyanate–alcohol reactions.

In Latin America and the Caribbean, the suitable processing of waste through the use of landfills is around 55%, while the local governments with municipal solid waste (MSW) management plans are around 20%. In Quito, for instance, approximately 2000 ton/day of solid waste are collected, and disposed in El Inga Landfill. The objective of this study is evaluating the MSW management of Quito through Life Cycle Assessment (LCA) approach. For achieving this goal, the ISO 14040 methodology was followed and SimaPro 8.4 was used as analysis software. The functional unit used is 1 ton of MSW, while, the material of study was the waste generated in households, commercial sector, schools and markets; whose values were obtained by the public companies EMASEO-EP, EMGIRS-EP, as well as from the open-access data of the city. The results show that using of biogas from the landfill allows the maximum saving of greenhouse gases (GHG) emissions. Therefore, the biogas plant is the process with less environmental impact. The compaction and transportation of MSW displayed a slightly higher impact comparing with the previous process, presenting the second-best environmental performance. On the other hand, the leachate treatment shows the greatest environmental impact according to the model, despite of the effluents does not exceed the permissible limits of the environmental Ecuadorian legislation. The researchers consider suitable the analysis of composting and anaerobic digestion techniques as complementary options to reduce this environmental impact, due to the high organic fraction in the analyzed waste

This study addresses the environmental challenge of end-of-life tire accumulation, a major source of toxic metals such as lead and cadmium in marine ecosystems. As a sustainable solution, multicomponent metal-oxide nanoparticles (Fe₃O₄, ZnO, CaO, MgO, and minor CaCO₃) were green-synthesized from sugarcane bagasse and stabilized with blackberry (Rubus glaucus) extract. Structural characterization (XRD, SEM, TEM, and EDS) confirmed their crystalline inorganic composition. Pb²⁺ was almost completely removed (95–99%) within 15–30 min using 50–100 mg of nanoparticles, with ~80–90% efficiency at 75 mg. Cd²⁺ removal showed dose-dependent kinetics: ~90% removal occurred within 10 min at 75 mg, while 50 and 100 mg reached ~60–70% after 60 min. Equilibrium, kinetic, and thermodynamic analyses revealed that Pb²⁺ adsorption followed the Langmuir model (R² = 0.982) with monolayer chemisorption, whereas Cd²⁺ obeyed the Freundlich model (R² = 0.945), indicating heterogeneous multilayer adsorption. Pb²⁺ removal fitted a pseudo-second-order model (R² = 0.991), while Cd²⁺ followed a pseudo-first-order behavior (R² = 0.958). Thermodynamic parameters (ΔG° < 0, ΔH° > 0, ΔS° > 0) confirmed a spontaneous and endothermic process. Sugarcane-bagasse-derived Fe₃O₄–ZnO–CaO–MgO nanomaterials act as sustainable and effective adsorbents for marine heavy metal removal.

Karst systems play a crucial role in drinking water supply and biodiversity. Therefore, their comprehensive characterization of their recharge mechanisms is essential for safeguard water resource quality and sustainable management. This study utilizes the open-access thematic cartography of Ecuador to analyze the lithological, geomorphological, and hydrographic boundaries of groundwater karst systems. Then, employing the APLIS method, the diffusive recharge for each system is calculated. As a result, five hydrogeological karst systems and twelve small isolated karst bodies were delineated within the Amazon Region of Ecuador, collectively occupying a total area of 11112 km2. The effective infiltration of precipitation within these systems was found to vary between 11.11% and 77.11%, with a predominant low infiltration range (20%-40%) covering 48% of the karst area. One of the multiple parameters used in water balance calculations is defined by this research, serving as the initial step in creating conceptual models for evaluating karst aquifer systems in Ecuador from a hydrological perspective. The findings not only offer insights into the vulnerability and characteristics of these systems but also establish the foundation for informed decision-making in sustainable groundwater resource management and protection efforts.