The Development of Green Schiff Base-Coated Papers Using Empty Palm Fruit Bunch Biomass for Enhanced Wet Strength

In this study, a sustainable cellulose-based Schiff base wet strength agent (WSA) was successfully synthesized from empty palm fruit bunch (EPFB) biomass. Cellulose isolated from EPFB was oxidized using sodium periodate to produce dialdehyde cellulose (DAC), which was subsequently reacted with six different amine precursors, methylamine (SB-1), ethylenediamine (SB-2), ethylamine (SB-3), diethylamine (SB-4), ethanolamine (SB-5), and diethanolamine (SB-6), to form cellulose-based Schiff base derivatives. Structural characterization by FTIR confirmed the formation of imine (CN) linkages, while XRD revealed a decrease in crystallinity after oxidation and Schiff base formation. SEM analysis demonstrated a progressive morphological transformation from fibrous cellulose to compact and aggregated Schiff base structures. BET results indicated a significant enhancement of the specific surface area, particularly for SB-2 (417.6 m² g^-1), suggesting improved interaction potential with paper fibers. Thermal analysis showed that cross-linked Schiff base structures exhibited modified thermal stability compared to DAC. Mechanical testing demonstrated substantial improvement in wet tensile strength, with SB-2 exhibiting the best performance, approaching that of commercial polyamide epichlorohydrin (PAE) agents. Biodegradability studies confirmed rapid degradation of all Schiff base samples, achieving nearly complete degradation within 20 days, outperforming conventional synthetic agents. These findings demonstrate that EPFB-derived Schiff base materials offer a promising, biodegradable, and biobased alternative to synthetic wet strength agents in paper applications.