Malays. J. Anal. Sci. Volume 30 Number 2 (2026): 1723

 

Research Article

 

Biopolymer-assisted synthesis of bifunctional mesoporous K₂O beads for one-pot esterification–transesterification in biodiesel production

 

Nor Badariah Talib1, Ong Hui Shan1, Jegthiswary Suresh1, Khairil Juhanni Abd Karim1, Nurrulhidayah Salamun1, Salmiah Jamal Mat Rosid2, and Susilawati Toemen1*

 

1 Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor, Malaysia

2 UniSZA Science and Medicine Foundation Centre, Universiti Sultan Zainal Abidin, Gong Badak Campus, 21300, Kuala Nerus, Terengganu, Malaysia

 

*Corresponding author: susilawatitoemen@utm.my

 

Received: 24 September 2025; Revised: 1 March 2026; Accepted: 7 April 2026; Published: 30 April 2026

 

Abstract

Transesterification is the preferred process for producing biodiesel, a sustainable fuel similar to fossil diesel. Potassium-based catalysts are highly valued in transesterification due to their remarkable basicity, well supported by numerous studies.In this study, mesoporous metal oxide (MMO) beads were synthesised using potassium precursor and biopolymers as templates to guide the formation of porous morphology with improved accessibility of active sites. Chitosan and alginate were evaluated, with chitosan demonstrating superior performance due to its strong affinity for potassium ions and abundant functional groups. Field Emission Scanning Electron Microscopy (FESEM) revealed a brain-like, wrinkled morphology of interconnected folds, which suggests mesoporosity properties. Nitrogen adsorption analysis supported this, showing an average pore diameter of 17.75 nm, and a pore volume of 0.039 cm³/g. X-ray diffraction (XRD) confirmed active basic center (K₂O, K₂O₂) and the presence of K₂CO₃·1.5H₂O, which acts both as a structural binder and acidic center. Hammett analysis suggests bifunctionality, with basicity of 1.346 mmol/g and acidity of 1.515 mmol/g. Under optimised synthesis conditions; K:chitosan monomer ratio of 4:1, 0.5  v/v% acetic acid, calcined at 700 °C for 2 h, the catalyst achieved a biodiesel yield of 95.17% from waste cooking oil (WCO), demonstrating the effectiveness of the synthesised catalysts in biodiesel production.

 

Keywords: biopolymer, mesoporous bead catalyst, biodiesel, bifunctional catalyst, potassium catalyst

 

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