RESUMO
Cellulose-based nanofiber membrane fabrication remains a global challenge, especially the use of alternative and sustainable sources of cellulosic materials. Herein, an easy and highly scalable cellulose-based nanofiber membrane was successfully fabricated using a solution blow spinning (SBS) method. Such membrane fabrication was carried out with the assistance of an easy-to-spin precursor polymer (i.e. polyacrylonitrile (PAN)). Through this strategy, cellulose acetate (CA) was successfully spun into a ready-to-use membrane. The formation of CA with the PAN nanofiber is concentration-dependent and requires high air pressure to effectively overcome the composite precursor's surface tension and eventually produce nanofibers. Favourable CA concentration in PAN (i.e. 50%-65% v/v CAN/PAN) is important to the formation of sufficient molecular entanglement with PAN in solution. Upon fulfilling the optimized CA concentration, high air pressure (i.e. ≥3 bars) is used to produce jet-like polymeric fibers of PAN dragging off CA, forming numerous nanofibers which are then collected into a substrate forming a membrane. Characterizations of the CA/PAN composite nanofiber were carried out using scanning electron microscopy, Fourier transform infrared, thermogravimetric analysis and differential scanning calorimetry (DSC). Such unique composite nanofiber membranes have potential as filters and adsorbent membranes for air and water/wastewater applications, as well as for biorefinery applications.
RESUMO
Mango seed kernel, a by-product of the processing industry, can be valorized as a potential source of bioactive compounds. Binary mixtures of ethanol and water, used in solid-liquid extraction (SLE), have drawn interest as an effective means of recovering phytochemicals from plant materials because these solvents can be used in food applications and their synergistic effect makes them a superior solvent over their pure counterparts. Total phenolic content (TPC) and HPLC chromatograms of each ethanolic extract revealed that ethanol concentration had a significant effect on phenolic compound recovery, wherein, TPC of mango kernel varied from 18.19 to 101.68 mg gallic acid equivalence (GAE) per gram of sample. Subsequently, the antioxidant activities (AOAc) of the extracts, measured by scavenging activities with the DPPH+ (1,1-diphenyl-2-picrylhydrazyl) radical and ferric reducing antioxidant power (FRAP) assay, ranged from 8.19 to 85.45 mmol/L and 3.82-55.61 mmol/L Trolox equivalence, respectively. The solvent containing 50% (w/w) ethanol-water had the highest TPC and exhibited the most potent reducing and radical scavenging activities. With the use of an HPLC-UV/Vis, gallic acid, caffeic acid, rutin and penta-O-galloyl-ß-d-glucose were identified to be present in the mango seed kernel. Results show that the mango seed kernel is a viable source of bioactive compounds which can be recovered with water-ethanol binary solvent systems.
