Abstract In the first part of this series of manuscripts, the focus was on discovering and delineating families of elementary step reactions and describing how the method of moments and the use of deterministically arranged dyad probabilities can be implemented within a population balance model to describe the thermal deconstruction of hydroxy-containing polymers. In this part, the results from the simulation of the pyrolysis of poly(vinyl alcohol) (PVA) and ethylene vinyl alcohol (EVOH) are compared to experimental thermogravimetric analysis and pyrolysis data obtained by carrying out using a micropyrolyzer coupled to two-dimensional chromatography, along with flame ionization and time-of-flight mass spectrometer detectors (Py–GC×GC–FID/TOF–MS). Both the PVA and EVOH models, using a heating rate of 10 °C min–1, were able to replicate experimentally determined mass-loss curves. In doing so, the difference in onset temperatures between the thermal deconstruction of PVA and EVOH was revealed to be the result of ethyl comonomers in EVOH chains inhibiting the rapid end-chain unzipping chemistries observed in PVA. Additionally, at low pyrolysis isothermal temperatures (340 and 360 °C), the EVOH model was able to reproduce the partial conversion yields of four major linear products, ethanal, 2-butenal, propene, and acetone, identifying the underlying chemical reactions that govern the thermal degradations of these polymers. After validating the model, net rate analysis was used to identify the major pathways for degradation in the PVA and EVOH systems, namely, assisted 1,2-dehydration, Grob-type 1,3-diol fragmentation, retro-aldol and (non)-adjacent retro-ene reactions. Lastly, to highlight the capabilities of this novel methodological framework and the reaction families at the elementary step level that it contains, this work further quantified the sensitivity of the degradation systems to backbone impurities and differing comonomer concentrations. With the successful validation of these models, this study has demonstrated a novel method of tracking the evolution of midchain topology probabilistically, expanding the suite of polymer pyrolysis systems that can be modeled using the method of moments, and presents the most detailed models of PVA and EVOH pyrolysis to date.
Abstract Liquid maldistribution remains a major source of uncertainty in the design and scale-up of packed columns. In this work, the RUB cell model is extended to structured packings and combined with a liquid film sensor-based tracer methodology in a miniaturized measuring cell. Tracer distribution experiments were conducted with Montz-Pak B1-250 structured packing under countercurrent air–water operation for liquid loads of 20–40 m3 m–2 h–1 and gas load factors of 0.93–2.8 Pa0.5. The measured tracer distributions reveal a clear transition from localized rivulet flow below the loading point to broader film-dominated liquid spreading at elevated gas loads. Based on these distributions, directional spreading coefficients were determined for cell model application. The fitted coefficients show physically consistent trends across the operating range, with nearly constant lateral redistribution below loading, first indications of altered redistribution behavior around the loading point, and increased redistribution toward flooding. The results demonstrate that the extended cell model captures the main changes in lateral liquid distribution in structured packings. Liquid film sensors integrated into miniaturized measuring cells therefore provide a robust and resource-efficient basis for cell model parametrization under realistic countercurrent operating conditions.
Abstract Resolving the inherent strength-toughness trade-off for simultaneous mechanical enhancement remains a long-standing challenge for polybenzoxazine (PBZ) composites in electronic packaging and equipment. Inspired by the hierarchical brick-and-mortar architecture of nacre, an epoxy resin bearing Si–O–Si flexible segments (ES) was incorporated into the cross-linked network of PBZ. The low-density glassy regions derived from the catalytic curing reaction among BZ, ES, and imidazole (IMD) acted as the flexible “mortar”, whereas high-density glassy regions constructed by the thermal curing reaction of PBZI and P(BZ-PESI) served as the rigid “brick”. Herein, the flexural strength, KIC, and impact strength of P(BZ-PESI20) blends with lower-dielectric properties were 114.3%, 304.9%, and 129.0% higher than those of neat PBZI, respectively. It was confirmed that the strengthening and toughening mechanism of the resins originated from the synergistic effects of improved cross-linking density, optimized high- and low-density glassy regions, and induced plastic deformation. These favorable mechanical and lower-dielectric properties were realized by tuning the network architectures and dynamic heterogeneity. This work offers economic and feasible prospects to circumvent the trade-off between strength and toughness and to advance the cross-linked network design of high-performance thermosetting polymers.
Abstract Electrochemical degradation of tetracycline (TC) using a mixed metal oxide (MMO) anode was investigated in the present study. The inefficiency of hydroxyl radicals for TC degradation was revealed by the minimal pollutant degradation observed in anodic oxidation and electro-Fenton processes. The addition of peroxymonosulfate (PMS) and peroxydisulfate (PDS) resulted in effective TC degradation, and PDS showed higher efficiency than PMS. The efficiency of the electrochemically activated PDS process was improved with the addition of iron-loaded biochar (FBC) as a catalyst; and the optimal efficiency of 78% was observed at the natural pH of a 100 ppm TC solution (pH 5.6), operated at 1 V, with 250 ppm PDS and 100 mg/L FBC. The process was effective over a wide pH range, from 3 to 9. In situ-generated sulfate radicals and singlet oxygen were found to be the predominant oxidants responsible for TC degradation, even in sewage, with 73.7% TC removal. The process also resulted in sewage disinfection, with a reduction in total coliforms from 1.48 × 1012 CFU/mL to 2.8 × 1011 CFU/mL, and in fecal coliforms from 6.9 × 1011 CFU/mL to 1.2 × 1011 CFU/mL, in addition to cell wall damage to nematodes and rotifers. Overall, electrochemical degradation is an effective approach for TC removal from aqueous media .
Abstract The rapid development of agricultural production has led to significant environmental pollution from agricultural waste, particularly wastewater containing high-value flavonoids like naringin (NRG). Traditional extraction methods for NRG suffer from high energy consumption, low selectivity, and environmental concerns. To address these challenges, this study develops a high-capacity boronate affinity imprinted macroporous polymer (HPs@MCNCs-PEI@Y–Br-MIPs) using a W/O Pickering high internal phase emulsion templating method. The resulting material exhibited exceptional adsorption capacity (61.02 μmol g–1), fast mass transfer (equilibrium in 120 min), and high selectivity (Imprinting factor = 3.62) for NRG. The adsorbent demonstrated excellent regeneration stability (92.95% capacity retention after 7 cycles) and successfully purified NRG from crude NRG, improving purity from 60% to 90.68%. This study provides a novel approach for the production of hyperbranched adsorbents with abundant and uniformly distributed binding sites, which enables the selective extraction of high-value flavonoids from agricultural waste.
