Abstract

The efficient utilization of natural resources and agricultural wastes aligns well with the UN Sustainable Development Goals. Sunflower seed husks are an affordable and renewable source of cellulose that can be used as an alternative to wood-based resources. However, the yield and quality of cellulose are affected by the presence of components such as phytomelanin, hemicellulose, and lignin. In this study, cellulose pulp (CP) was extracted from untreated, water-treated, and water and alkali-treated SFH. The optimal peroxyacetic acid (PAA) to biomass ratio was established to assess the influence of pre-treatment on CP properties. Water and alkali pre-treatments significantly increased CP yield and reduced residual lignin, hemicellulose, and ash compared to untreated samples. The optimal yield of CP for SFH-NaOH was 55.73%. All microcrystalline cellulose (MCC) types exhibited comparable α-cellulose content, confirmed by the IR band at 1430 cm−1. XRD showed lower crystallinity in untreated CP-SFH relative to pre-treated samples. SEM revealed porous fibrous structures across all MCCs. Pre-treatment also improved the thermal stability and ζ-potential of cellulose nanocrystals (CNCs) obtained from MCC, without altering morphology. CNC yields were determined for all three CP variants. The CP-SFH-NaOH sample had the maximum CNC yield of 52.12%. Phytomelanin with admixture of lignin was recovered from alkaline extracts (8.56%) and fully characterized. Overall, the findings demonstrate the potential of integrated SFH utilization to produce high-quality cellulose derivatives and phytomelanin with admixture of lignin.

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