Copper-catalyzed oxidative coupling links coordination chemistry to the manufacture of poly(2,6-dimethyl-1,4-phenylene oxide), also termed poly(phenylene ether) (PPO/PPE). This critical narrative review examines how ligand architecture, halide coordination, solvent, base, and oxygen availability influence copper speciation and phenolic coupling. A historical account connects early copper–amine formulations with diamine catalysts, mechanistic and spectroscopic studies, aqueous polymerization, and supported catalyst designs. Particular attention is given to Cu–diamine–halide systems investigated through the oxidation of 2,6-di-tert-butylphenol (DTBP) to diphenoquinone. These experiments establish condition-specific correlations between solution composition and activity, but do not by themselves identify the species controlling C–O-selective polymerization of 2,6-dimethylphenol. Radical, phenoxonium, and copper–oxygen pathways are evaluated according to the evidence supporting each proposed step. The industrial discussion connects polymer structure and purification to engineering blends, electrical components, water-management applications, reactive oligomers, emerging functional membranes, and experimental pollutant-to-polymer recovery. Across these applications, catalyst assessment requires more than substrate conversion: C–O selectivity, molar-mass distribution, end-group chemistry, residual copper, and process requirements also warrant consideration. Recent coupled spectroscopic methods provide precedents for tracking transient copper species; extending such measurements to PPO turnover, together with product-resolved kinetics and polymer characterization, offers a practical route toward predictive catalyst design.
This work is devoted to the calculation and prediction of filler-matrix macromolecule interactions in the polymer-polysaccharide system. A technique is presented that includes the analysis of the chemical structure of polymers, the determination of functional groups and additive molar functions, and the calculation of thermodynamic compatibility parameters. The group additive method does not require special programming skills and allows one to effectively estimate the energetic parameters of matrix-filler interface and the compatibility parameter of the polymer matrix with the polysaccharide. The thermodynamic compatibility parameter is calculated for one of the most widely used synthetic polymers—polyethylene, and for one of the most well-known biodegradable polyesters—polylactide. Cellulose, hemicelluloses, and lignin were selected as the second component. The results demonstrate the importance of considering the physical and structural characteristics of polymers when choosing materials for creating composites.
Cerium oxide (CeO2) is a key rare-earth material for catalysis and energy applications, yet quantitative links between synthesis parameters, morphology, and defect chemistry remain scarce. Using three selected conditions from a broader synthesis matrix with octadecylamine (ODA) concentration (0.01–0.2 M) and ethanol/water ratio (α = 0.3–3.0), we obtained three distinct morphologies: spherulites (CeO2-AA), short nanorods (CeO2-BB), and long rods (CeO2-MM). CeO2-BB nanorods exhibit the highest BET surface area (79.9 m2/g), Ce3+ content (30.2%), and Odef/Olat ratio (0.99), while CeO2-MM shows an Odef/Olat ratio of 0.80. A controlled comparison with commercial 25 nm CeO2 (similar crystallite size, 21.3 nm, but 60× lower microstrain) reveals that, within the investigated sample set, microstrain and defect-related disorder are the dominant contributors to Raman F2g broadening, rather than phonon confinement. The ID/IF2g ratio correlates strongly with Ce3+ content (R2 = 0.94), supporting Raman as a sensitive indicator of defect-related disorder or oxygen-vacancy-associated defects. Qualitative inspection of the data suggests that ODA concentration has a more pronounced influence on aspect ratio, Ce3+ content, and bandgap than the ethanol/water ratio, although the limited number of synthesis conditions precludes definitive statistical ranking. This integrated framework enables rational design of CeO2 nanostructures with tailored defect chemistry for catalysis and rare-earth-based applications.
Direct air capture (DAC) with supported amines depends on reversible CO2–amine interactions within a confined phase, so working capacity is governed by both access to the amine-containing phase and regeneration conditions. In this study, tetraethylenepentamine (TEPA)- and polyethylenimine (PEI)-functionalized biomass-derived porous carbons were evaluated in a fixed-bed system at 500 ppm CO2. TEPA samples showed substantially higher amine-mass-normalized uptake than PEI at comparable loading, indicating more favorable adsorption-transport behavior under the fixed-bed conditions. TEP-30 and TEP-40 reached 0.38–0.39 mmol g−1 under dry atmospheric-pressure conditions. Increasing the adsorption pressure to 0.2 MPa(g) raised the TEP-30 capacity to 0.58 mmol g−1. Regeneration at 110 °C caused rapid capacity loss, whereas vacuum alone at 500 Pa was insufficient. Coupling 80 °C with 500 Pa improved short-term cyclic working-capacity retention under the tested cycles by combining thermal activation of desorption with a low gas-phase CO2 chemical potential. The results establish a reaction–transport framework for interpreting supported-amine DAC and demonstrate the potential of moderate-temperature, deep-vacuum regeneration under the tested fixed-bed cycles.
Electrochemical oxidation (EO) is a versatile, advanced oxidation process (AOP) for the treatment of persistent and recalcitrant pollutants in wastewater. This critical review examines recent advances in EO, with emphasis on oxidation mechanisms, electrode materials, reactive species, reactor configurations, operational parameters, and energy efficiency. Direct electron-transfer reactions and indirect oxidation mediated by electrogenerated reactive species are discussed in relation to pollutant degradation, mineralization, and process selectivity. Attention is given to active and non-active anodes, classified according to their interaction with electrogenerated oxidizing species and their catalytic behavior toward organic pollutant oxidation, as well as to electrode stability and oxygen evolution competition. The effects of parameters such as current density applied potential, pH, electrolyte composition, conductivity, temperature, mass transfer, and electrolysis time on treatment performance and energy consumption are critically evaluated. The review also examines the integration of EO with microbial electrochemical technologies, anaerobic digestion, hydrogen production, and other resource-recovery pathways, distinguishing direct electrochemical energy recovery from downstream energy generation. Photo-electrooxidation is considered as a complementary light-assisted electrochemical approach. Importantly, the available evidence does not yet support generalized claims of positive net energy recovery, highlighting the need for complete system-level energy balances. Finally, key challenges related to real wastewater, electrode durability, transformation products, toxicity, scale-up, techno-economic feasibility, and environmental sustainability are discussed, together with future perspectives for efficient and scalable EO-based wastewater treatment.
