Amine-Functionalized Lignin as an Eco-Friendly Antioxidant for Rubber Compounds

Although the typical antioxidant, N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine (6PPD), ensures high durability and long lifespan for rubber compounds, it generates a highly toxic quinone in water, causing serious environmental pollution. Herein, as an alternative material of 6PPD, we newly introduce eco-friendly amine-functionalized lignin (AL) to be incorporated in rubber, which can provide excellent combinatorial antiaging properties of thermal stability and ozone/fatigue resistances through radical scavenging effect. The heterolytic ring-opening reaction of AL and sulfur can accelerate curing and improve the cross-link density by 28% (v, 4.107 × 10–4 mol/cm3), consequently reducing the ozone vulnerable areas of the matrix and further improving the aging resistance. Notably, AL allows its rubber compound to exhibit superior anti-ozone performance after ozone aging, with the arithmetic surface roughness (Sa) of 2.077 μm, which should be compared to that of 6PPD (4.737 μm). The developed chemically modified lignin and the methodology have enormous potential as a promising additive for future eco-friendly rubber compounds. The eco-friendly lignin-based antioxidant manufactured by amination reaction has the potential to reduce environmental pollution for the future rubber industry

Self-Tunable, Exfoliated Oxygen-Rich Flower-like MoS₂ Nanosheets for Arsenic Removal: Investigations on Substitution, Stability, and Sustainability (3S) for Maxi-Sorption

In this study, we synthesized La-incorporated O-rich defective MoS2 nanosheets by a simple, inexpensive, in situ hydrothermal reaction to self-exfoliate the bulky MoS2 layers themselves so that they can readily trap hard base anions, arsenic (arsenite and arsenate), from water. Attempting to modify MoS2 surfaces by incorporating O allows for more active sites, which is confirmed by powder XRD patterns where the exfoliated layers have a d-spacing of 0.63 nm, while the spacing for the bulky layers is 0.60 nm. The substitution of La at different equivalent ratios on the interlayer/surface improves the adsorption properties of arsenite and arsenate in simple solutions, as shown by the Langmuir adsorption density values of 0.7760 and 1.4363 mmol g–1, respectively. When the O-rich MoS2 layers were loaded with La, the adsorption densities improved, with La1.0 equiv showing the best values among the materials studied. The presence of O and S was more responsible for the removal of arsenite ions, and La and O, together with a small amount of N, were able to remove arsenate ions from water according to the well-known Pearson’s Lewis acid−base principle. The stability of the materials was characterized after the experiments, and it was found that there was no leaching of the materials by ICP-OES and the stability was maintained after 6 regeneration cycles. With the exception of phosphate, which behaves chemically similar to arsenic, the adsorption densities were not significantly affected by the mono- and divalent anions, indicating the selectivity of the prepared materials. The synthesis cost of MoOxS2–x was 2 times lower than that of bulky MoS2, and its adsorption properties were 10 times higher than those of the latter. The results suggest that La-substituted O-rich MoS2 is a potential candidate for the removal of soft and hard base metals from water