Faraday Discussions最新文献

Plastics are ubiquitous in modern society; however, their disposal at end-of-life remains challenging. Enzymatic recycling offers a potential low-energy solution to recycling poly(ethylene terephthalate) (PET); however, high-crystallinity substrates such as polyester textiles are recalcitrant to enzymatic hydrolysis. Current amorphisation pretreatments yield substrates amenable to enzymatic digestion; however, they account for a significant percentage of all process electricity requirements. Here we investigate dissolution–reprecipitation with the green solvents gamma-valerolactone and 2-isopropylphenol as a lower-energy pretreatment regime. We find that whilst there is only a minimal decrease in substrate crystallinity, activity of the benchmark PET hydrolase LCC^ICCG is increased on all solvent-treated substrates. We show that GVL negatively impacts the thermostability of LCC^ICCG, and both solvents dramatically decrease enzyme activity, from concentrations as low as 4%, highlighting the need for effective solvent removal following pretreatment. Finally, we show that IPP and GVL are effective for the removal of synthetic dyes from polyester textiles, enabling new applications for these solvents in PET recycling.

This Faraday Discussions meeting has shown that a wide range of physical techniques allows imaging biominerals whatever their size, mineralogy and complexity. These techniques cover an extensive spectral range from infrared to hard X-rays and enable the micro- and nano-structures of these exceptional biological materials to be described in great detail. All scales are covered, with numerous overlaps, from the millimetre to atomic scales. The next frontier will be to map in 3D the organic matrix components associated with biominerals in order to understand their function in biomineralization.

Polylactide (PLA) is one of the most promising bioplastics and is therefore often quoted as a solution to fight today's global plastics crisis. However, current PLA production via the ring-opening polymerization (ROP) of lactide is not yet sustainable since it heavily relies on the toxic catalyst tin octoate. To overcome the hurdles in scale-up and to accelerate the transition of promising new non-toxic alternative ROP catalysts from laboratory to industry, model-based analysis is a highly effective tool. Herein, our previously introduced kinetic model for the ROP of L-lactide using a non-toxic and robust Zn guanidine “asme”-type catalyst under industrially relevant melt conditions is expanded upon using two new co-initiators. The experimental data is evaluated using “traditional” kinetic analysis following pseudo-first-order kinetics to approximate a relationship between co-initiator concentration and the rate of polymerization. The range of validity of these findings is considerably expanded by taking model data into account to compare the performance of the different co-initiators in lactide ROP.

While the challenges of incorporating raw softwood kraft lignin (KL) as particulate pigments in epoxy coatings were addressed using mechanically sieved, size-fractionated lignin, and its corrosion resistance was evaluated, a key question remains: does solvent fractionation, which yields lower molecular weight lignin, offer improved barrier performance? This study explores the use of lignin as a functional particulate pigment in an amine-cured epoxy-based anticorrosive coating (EP), with a particular focus on how its molecular weight influences water uptake and transport behavior. Three pigmented epoxy systems with well-defined particle size distributions were investigated: a high molecular weight (M_w) kraft lignin incorporated via mechanical sieving (KL-sieved-EP, 5–30 μm), a low M_w lignin fraction obtained through ethyl acetate solvent fractionation (KL-EtOAc-EP, 5–10 μm), and a conventional acicular-shaped iron oxide pigment (FeOOH-EP, ∼0.3 × 0.5 μm). To evaluate the barrier performance of these coatings, water uptake behavior was systematically analyzed using gravimetric mass gain and electrochemical impedance spectroscopy (EIS), enabling assessment of both surface and bulk water transport pathways. The results show that KL-sieved-EP had the highest equilibrium water uptake, compared to KL-EtOAc-EP, which exhibited the lowest water uptake and diffusion coefficients, indicating superior compatibility with the epoxy matrix and a more cohesive barrier. These differences can be linked to the extent of supramolecular aggregation in the lignin: high molecular weight lignin tends to retain strong supramolecular associations, which limit its interaction with the epoxy. In contrast, solvent-fractionated low molecular weight lignin disrupts this aggregation, allowing for enhanced dispersion and integration within the epoxy network. The conventional FeOOH-EP coating showed a similar equilibrium water uptake to KL-EtOAc-EP based on gravimetric analysis but exhibited the highest diffusion coefficient among the three systems, indicating faster water transport. Although both had comparable total water uptake, EIS measurements revealed higher overall water absorption in FeOOH-EP. In contrast, KL-EtOAc-EP maintained extremely low water uptake in both gravimetric and EIS measurements. This contrast highlights a key finding: lignin-based systems, particularly KL-EtOAc-EP, showed no clear pigment–binder interface under SEM, which may contribute to their more uniform, defect-free morphology and improved barrier performance.