Effect of Microwave Application on the Xylan Extraction Yield from Agri-Waste Corncob for Sustainable Biomass Valorization: A Response Surface Methodology Optimization and Extract Characterization.

The global demand for sustainable resources highlights agricultural wastes for their valuable biomass content. Xylan, abundant in nature, offers biomedical applications in drug delivery, wound healing, and biodegradable food coatings. This study is the first in the literature to investigate the effect of microwaves on xylan extraction. The aim of this study is to investigate the effect of microwave application and determine the purity of the extraction outcomes in terms of xylan content. The microwave-assisted extractions were performed with two different diluted alkali solutions, potassium hydroxide (KOH) and sodium hydroxide (NaOH), and corncob was the biomass source for xylan. Experiments were designed with response surface methodology (RSM) to find the optimum conditions. Microwave energy demonstrated a statistically significant impact on extraction efficiency and yield (p < 0.05). Maximum yielding conditions for xylan extractions were found as follows: 1200-watt microwave power for 20 min with 10% (w/v) alkaline solution. The results of Fourier-transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance (NMR) spectra of the KOH extract showed more resemblance to the xylan standard, with fewer indicators of impurities. However, the differential scanning calorimetry (DSC) and zeta potential analysis results of the two extracts did not differ from each other, showing similar thermal and suspension behavior. Xylan content of the KOH and NaOH extracts was determined as 77.82% and 72.01%, respectively.