Delignification of Kelakai (Stenochlaena palustris) Using Sodium Hydroxide Solution: Implications on Thermal Decomposition and Kinetic Parameters

Khairunnisa Aprilianti; Hesti Wijayanti; Abubakar Tuhuloula; Iryanti Fatyasari Nata

doi:10.33795/jtkl.v10i2.9341

Authors

Khairunnisa Aprilianti Department of Chemical Engineering, Faculty of Engineering, Lambung Mangkurat University, South Kalimantan 70714, Indonesia
Hesti Wijayanti Department of Chemical Engineering, Faculty of Engineering, Lambung Mangkurat University, South Kalimantan 70714, Indonesia
Abubakar Tuhuloula Department of Chemical Engineering, Faculty of Engineering, Lambung Mangkurat University, South Kalimantan 70714, Indonesia
Iryanti Fatyasari Nata Department of Chemical Engineering, Faculty of Engineering, Lambung Mangkurat University, South Kalimantan 70714, Indonesia

DOI:

https://doi.org/10.33795/jtkl.v10i2.9341

Keywords:

activation energy, kelakai, kinetic, NaOH solution treatment, thermal stability

Abstract

Kelakai (Stenochlaena palustris) is a highly abundant wetland biomass with significant potential as a renewable energy resource. However, its high lignin content often hinders the efficiency of thermal conversion processes. This study investigated the implications of delignification using several concentrations of sodium hydroxide (NaOH) solution on thermal decomposition and kinetic parameters of kelakai. While alkali treatment is common for wood-based biomass, its specific impact on the thermal kinetics of wetland ferns remains underexplored. The objective of this research is to evaluate how reducing lignin through NaOH pretreatment enhances the quality of kelakai as a pyrolysis feedstock. Samples were treated with 3, 10, and 15% NaOH solution at 80℃ under stirring at 200 rpm for 1 hour. Characterization was conducted using Thermogravimetric Analysis (TGA), and kinetic parameters were determined via the Coats – Redfern method. The results showed that NaOH treatment significantly shifted the lignocellulosic composition. The cellulose fraction increased from 29.64% (untreated) to 64.15% with 15% NaOH solution. Meanwhile, lignin decreased from 33.23% to 5.18% with 15% NaOH solution. TGA profiles indicated that delignified samples decomposed at a higher temperature range (245 – 380℃) with a highly significant reduction in char residue, indicating more efficient volatile conversion. Kinetic analysis demonstrated that activation energy increased from 20.42 kJ/mol (untreated) to 44.90 kJ/mol at 3% NaOH, followed by a slight decrease at higher concentrations. This behavior suggests that moderate delignification enhances cellulose structural organization and thermal stability, whereas excessive alkali treatment leads to partial cellulose degradation. These findings indicate that moderate NaOH delignification improves the thermal stability and kinetic behavior of kelakai, making it a promising feedstock for pyrolysis-based bioenergy applications.

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