Abelmoschus manihot (A. manihot) flowers are well studied, but its fruit, leaf, stem, and root bio-wastes remain underutilized. This study developed a green ultrasonic-assisted extraction (UAE) process using a temperature-controlled bath (40 kHz, 12 L). Calorimetric calibration established linear acoustic energy output (R2 = 0.9942), and a medium acoustic energy density of 113.6 W/L was selected. This energy density ensured stable cavitation during extraction. KI dosimetry quantified cavitation: triiodide concentration increased with power above a threshold, and time-course data were fitted by both linear and nonlinear models, confirming continuous sonochemical activity. Water, ethanol, and water/ethanol (1:1, v/v) were compared under UAE and shake-assisted extraction. Water/ethanol with UAE gave the highest polyphenol yields and antioxidant activities, with a net increment of 3.87 mg GAE g−1 for leaf. Pseudo-second-order kinetics best described extraction, and UAE increased rate constants, indicating reduced mass transfer resistance. SEM revealed ultrasound-induced cell wall disruption, more pronounced in leaf and fruit than in lignified stem and root. Extraction parameters were optimized by response surface methodology and back-propagation artificial neural network, with the latter superior. Antioxidant assays ranked fruit > leaf > stem > root. UHPLC-MS/MS metabolomics identified 508 polyphenols dominated by flavonoids (57.75 %) and phenolic acids (38.76 %), with tissue-specific accumulation. Mantel test showed flavonoids and phenolic acids strongly correlated with antioxidant activity, with tannins playing auxiliary roles. This integrated acoustic, kinetic, and microstructural evidence provides a mechanistic basis for ultrasound-enhanced polyphenol recovery. These findings demonstrate the greenness and potential of UAE for recovering polyphenols from agricultural bio-wastes.
The effect of oxygen-functionalized graphene oxide (GO) introduced during sonochemical synthesis on the nanostructural growth, crystal structure, and surface chemistry of layered potassium vanadate was investigated. Two distinct modification regimes were identified depending on GO loading. Lower GO loadings primarily altered the crystal structure, which enhanced capacity mainly at low current densities without sustaining this advantage at high current densities. Higher GO loadings additionally modified the surface chemistry, which, combined with expanded interlayer spacing, increased capacity across all current densities and preserved high-rate capability. The vanadate synthesized with 10 wt% GO (denoted as GP10), in which both structural and surface-chemical modifications were observed, exhibited the best rate performance among the samples studied and maintained a high capacity of 251.9 mAh g−1 after 1000 cycles at 10 A g−1, which was 1.6 times that of the GO-free potassium vanadate nanofibers (PVNF). At 20 A g−1, GP10 achieved an energy density of 152.8 Wh kg−1 (twice that of PVNF) at a power density of 11,317 W kg−1. This study demonstrates that incorporating GO during synthesis enables the comprehensive engineering of layered vanadate through simultaneous modification of the crystal structure and surface chemistry toward high-performance cathodes for aqueous zinc-ion batteries (AZIBs).
Seaweeds are emerging as versatile and promising sources of bioactive compounds with applications in food, feed, and nutraceuticals. This study explored ultrasound-assisted extraction using a deep eutectic solvent (choline chloride: lactic acid) to enhance the co-extraction of proteins and soluble carbohydrates from Saccharina latissima . Extraction parameters, ultrasound amplitude (70–90%), sonication time (5–15 min), and solid-to-solvent ratio (3–7%) were optimised using response surface methodology with a Box-Behnken design. Total protein content (TPC) and total soluble carbohydrate content (TSC) were used as the two primary responses for model development and numerical optimisation, while protein recovery yield (PRY) and carbohydrate recovery yield (CRY) were calculated from the corresponding TPC and TSC values. The optimised conditions (88% amplitude, 12 min sonication, and 3% solid-to-solvent ratio) yielded a TPC of 50.98 mg BSAE/g of ethanol-pretreated and dried seaweed and a TSC of 431.09 mg GE/g of ethanol-pretreated and dried seaweed, corresponding to protein and carbohydrate recovery yields of 56.58% and 83.54%, respectively. The optimised condition was validated experimentally. The developed models for the two responses were highly significant (p < 0.0001), with coefficients of determination (R 2 ) exceeding 0.98. The optimised ultrasound-assisted deep eutectic solvent (US-DES) extraction approach significantly enhanced antioxidant capacity, achieving 73.46 ± 1.3% DPPH radical scavenging activity and 134.48 ± 1.67 µM TE/mL of extract for FRAP. Fucose content was maximally recovered under the same conditions (20.56 ± 0.46 mg/g of ethanol-pretreated and dried seaweed). FTIR and SEM analyses revealed changes in the biomass functional-group profiles and surface morphology following extraction. Overall, this study demonstrates the potential of ultrasound-assisted DES extraction for recovering protein- and carbohydrate-rich fractions from S. latissima , with promising antioxidant capacity.
