Malays. J. Anal. Sci. Volume 29 Number 4 (2025): 1354

 

Research Article

 

Influence of crosslinker and monomer concentration on the swelling behaviour and morphological characteristics of hemicellulose-based hydrogels from oil palm empty fruit bunches

 

Sabiha Hanim Saleh1,2*, Nur Syafiqah Antashah Azaha1, Nurul Asyikin Abd Halim1, Shariff Ibrahim1,2, Mohammed Falalu Hamza1, Noraini Hamzah1,2

 

1School of Chemistry and Environment, Faculty of Applied Sciences, Universiti Teknologi MARA, 40450 Shah Alam, Selangor, Malaysia

2Industrial Waste Conversion Technology Research Group, Faculty of Applied Sciences, Universiti Teknologi MARA, 40450 Shah Alam, Selangor, Malaysia

 

*Corresponding author: sabihahanim@uitm.edu.my

 

Received: 19 September 2024; Revised: 28 June 2025; Accepted: 2 July 2025; Published: 22 August 2025

 

Abstract

This study investigates the extraction of hemicellulose from oil palm empty fruit bunches (OPEFB) and its subsequent use in the synthesis of hemicellulose-based nanocomposite hydrogels. Given the limited understanding of how the crosslinker and monomer concentration affect the properties of these hydrogels, further exploration is essential. Six distinct hydrogels were synthesised by varying the amounts of the crosslinker N,N′-methylenebisacrylamide (MBA) and the monomer acrylic acid (AA). The primary aim was to evaluate the impact of these variations on the swelling behaviour of the hydrogels. Hemicellulose extraction was performed using a microwave-assisted alkaline solution at 130 °C for 30 min, and the extracted hemicellulose was then utilised to prepare the hydrogels. Swelling studies indicated that the hydrogel with 0.5% MBA exhibited the highest swelling percentage at 1008%, while the optimal monomer concentration of 20% achieved a swelling percentage of 1933%. Fourier Transform infrared spectroscopy identified key functional groups, including O-H, C≡C, C=O, and C-O stretches, reflecting differences in crosslinker and monomer concentrations. Field emission scanning electron microscopy analysis revealed distinct surface morphologies influenced by both crosslinker and monomer concentrations. Hydrogels with lower MBA (0.1%) and moderate AA (20%) exhibited rougher, more open surfaces, while higher MBA (1.0%) and AA (22%) contents resulted in smoother, denser structures. The optimal swelling performance was observed in samples with 0.5% MBA and 20% AA, corresponding to a well-balanced network structure. These findings highlight the critical need to optimise the crosslinker-to-monomer ratio and the concentrations of these components to develop hydrogels with desirable swelling properties and structural characteristics.

 

Keywords: crosslinker, monomer, oil palm empty fruit bunches, hydrogel, hemicellulose

 

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