Sintesis Wet Strength Agent (WSA) Berbasis Selulosa melalui Reaksi antara Selulosa Dialdehida dengan Dietanolamina

Abstract

The synthesis of a cellulose-based wet strength agent (WSA) was carried out by isolating cellulose from oil palm empty fruit bunches (EFB) using HNO₃, NaOH, Na₂SO₃, NaOCl, and H₂O₂ solutions, yielding 19.102 g of cellulose (25.47% of the initial mass). The cellulose was then oxidized with NaIO₄ for 3, 6, and 9 hours to produce dialdehyde cellulose (DAC). The presence of aldehyde groups was confirmed through Fehling’s test, increased solubility in hot water, and the appearance of a carbonyl band at 1674.68 cm⁻¹. The 9-hour reaction produced the highest oxidation degree and carbonyl content, namely 56.55% and 13.3%, respectively. SEM analysis showed that the DAC morphology became smoother and more irregular, while PSA measurements indicated a reduction in particle size to 307 ± 83 nm. The reaction between DAC and diethanolamine yielded an iminium-containing product. The FT-IR spectrum showed a decrease in carbonyl intensity along with the emergence of a C=N⁺ band at 1650 cm⁻¹, confirming the presence of the iminium group. The product contained 4.86% nitrogen and exhibited more wrinkled and irregular fiber morphology based on SEM images. PSA recorded an average particle size of 137 ± 14 nm. The cellulose-based WSA was then applied to paper sheets to evaluate its mechanical reinforcement performance. The results showed that the positively charged iminium groups enhanced electrostatic interactions and inter-fiber bonding, leading to a substantial improvement in tensile strength. The dry tensile strength reached 370 N/m, exceeding the typical performance of PAE-based WSAs, which generally range from 250–320 N/m, while the wet tensile strength reached 90 N/m. Both values surpassed the requirements of SNI 3344:2019, demonstrating that the synthesized cellulose-based WSA functions effectively as a paper wet-strength agent, with performance that is competitive with—and in some aspects superior to—conventional synthetic WSAs.