Green algae derived cellulose for PEG composite: A comprehensive study on synthesis, characterization and anticorrosion applications

The present study investigates the transformation of algae waste into PEG/cellulose nanocomposites through a series of chemical treatments, analyzing their structural, morphological, and physicochemical properties. FTIR analysis revealed progressive chemical modifications, including the emergence of carboxylate peaks (1400-1450 cm⁻¹) after alkali treatment and C=O stretching (1750-1800 cm⁻¹) following bleaching. XRD analysis showed that the crystallinity index increased from 47.0% (raw algae waste) to 49.5% (alkali-treated), but decreased to 35.5% upon PEG incorporation, indicating disruption of cellulose’s ordered structure. SEM images depicted morphological evolution from a heterogeneous matrix to a highly fibrillated structure post-acid hydrolysis, with PEG grafting leading to a more compact morphology. Zeta potential analysis revealed surface charge variations, with values decreasing from -18.2 mV (raw) to -22.6 mV (alkali-treated), while PEG grafting reduced it to -10.4 mV, suggesting steric stabilization. DLS results confirmed a reduction in hydrodynamic diameter from 450 nm (raw) to 215 nm (acid-hydrolyzed), highlighting size refinement. Anticorrosion properties were evaluated using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) in a 3.5 wt% NaCl solution, revealing a corrosion inhibition efficiency of 87.6% at an optimal composite concentration. These findings highlight the potential of algae-derived cellulose-based PEG composites as eco-friendly corrosion inhibitors for metal protection in marine and industrial environments.