One stone, two birds: An eco-friendly aerogel based on waste pomelo peel cellulose for the efficient adsorption of dyes and heavy metal ions.

To achieve the objective of "waste control by waste", in this study, a green aerogel adsorbent comprised of pomelo-peel cellulose and sodium alginate (PCC/SA) was prepared through dual-network crosslinking. The resulting 3D hierarchical porous structured PCC/SA aerogel exhibited good structural stability, and kept the morphological integrity during 10 days in a wide pH range (2-10), suggesting its potential for recycling in diverse complex environments. Besides, the superior adsorption capacities for methylene blue (MB) and Cu(II) were observed, with the qm values and adsorption equilibrium times were recorded to be 1299.59 mg/g (300 min) and 287.55 mg/g (120 min), correspondingly. Furthermore, the favorable reusability of the PCC/SA aerogel was also demonstrated, with the removal efficiency for MB remaining almost unchanged (about 94 %) after 10 adsorption-desorption cycles, while there was a slight reduction for Cu(II) from 85.28 % to 72.47 %. XPS and FTIR analysis revealed that electrostatic attraction, hydrogen bonding, cation exchange and coordination were the major adsorption mechanisms. Importantly, the PCC/SA aerogel can be naturally degraded in soil within 10 weeks. Therefore, the as-prepared aerogel bead derived from pomelo peel shows great promise as an adsorbent for wastewater treatment containing dye and heavy metal ions.

Fabrication of alkali lignin-based emulsion electrospun nanofibers for the nanoencapsulation of beta-carotene and the enhanced antioxidant property.

For the greater utilization of ß-carotene in antioxidant material, ß-carotene-loaded emulsion stabilized by alkali lignin (AL) was successfully electrospinning with poly (vinyl alcohol) (PVA) (PVA/AL/ß-carotene nanofiber). Transmission electron microscopy demonstrated the core-shell structure of nanofiber with the average diameter being 356.31 nm, and 85.7 % of ß-carotene was effectively encapsulated into the core section. Fourier transform infrared spectra and differential scanning calorimetry revealed the good compatibility and decreased crystallinity of ß-carotene, favoring its stability and solubility, respectively. As expected, the PVA/AL/ß-carotene nanofiber exhibited higher antioxidant activity than free ß-carotene due to the protection of AL matrix and the special structure of nanofiber, as the DPPH free radical scavenging rate being 90.7 % at 7th day. The sustained release behavior of ß-carotene and AL from fiber followed Fickian diffusion model, contributing to the greater protection for fish oil than that of emulsion. Thus, this study provides an approach to develop hydrophobic compounds-loaded emulsion electrospun antioxidant material with controlled release property and enhanced activity.