OxiOrganosolv delignification of corncob within an integrated biorefinery route for the production of a bio-based polymeric flocculant

Most polymers are still derived from petroleum, making the biorefining of agricultural by-products a sustainable alternative. In this study, an integrated biorefinery route is proposed for the production of a bio-based polymeric flocculant from corncob (CC), combining OxiOrganosolv pretreatment and subsequent chemical functionalization. The delignification process, based on a synergistic system of hydrogen peroxide (H₂O₂) and alkaline ethanol (EtOH/NaOH), was optimized using response surface methodology coupled with multi-objective analysis, desirability function, and Scott–Knott test. Under the selected conditions (EtOH/H₂O₂ ratio of 1:1 and 10% NaOH), a delignification efficiency of 91.49 ± 0.53% was achieved within 30 min. From the corncob, 63.97% of lignin, 75.75% of cellulose, and 87.82% of hemicelluloses (w/w) were recovered. The recovered hemicelluloses were chemically modified via cationization with 3-chloro-2-hydroxypropyltrimethylammonium chloride (CHPTAC), resulting in a cationic bio-based flocculant with a degree of substitution of 0.59. This modification shifted the zeta potential from –19.18 mV to a strongly positive + 41.49 mV. Treatability tests raw surface water collected from the Uberabinha River (Brazil), demonstrated high performance, with cationic hemicelluloses (CH) achieving 95% turbidity removal efficiency at low dosages (< 1 ppm). Under the same conditions, aluminum sulfate (Al 2 (SO 4 ) 3 ) achieved comparable removal (92%) but required significantly higher dosages (8.5 ppm), highlighting the superior efficiency of the hemicellulose-based flocculant. This integrated biorefinery route establishes an environmentally friendly delignification method aligned with green chemistry principles, enabling the production of high-performance polymeric flocculants by converting agro-industrial residues into biorefinery feedstocks.