Comparative Study of the Single and Double-Stage Thermochemical Pretreatment of Gracilaria sp. for Biogas Feedstock

Elli Prastyo; Rochim Bakti Cahyono; Lisendra Marbelia; Wiratni Budhijanto

doi:10.5614/j.eng.technol.sci.2026.58.1.6

Comparative Study of the Single and Double-Stage Thermochemical Pretreatment of Gracilaria sp. for Biogas Feedstock

Published: 2026-01-01 | DOI: 10.5614/j.eng.technol.sci.2026.58.1.6 | Vol 58, Issue 1 (2026)

Authors

Elli Prastyo

Department of Chemical Engineering, Faculty of Engineering, Universitas Gadjah Mada, Jalan Grafika 2, Yogyakarta 55281,

ORCID: 0009-0001-2163-7065 · OpenAlex: A5003221914

Rochim Bakti Cahyono

Department of Chemical Engineering, Faculty of Engineering, Universitas Gadjah Mada, Jalan Grafika 2, Yogyakarta 55281,

ORCID: 0000-0001-6366-1920 · OpenAlex: A5001067825

Lisendra Marbelia

Bioprocess Engineering Research Group, Universitas Gadjah Mada, Jalan Grafika No. 2, Sleman, Yogyakarta 55281

OpenAlex: A5036387163

Wiratni Budhijanto

Bioprocess Engineering Research Group, Universitas Gadjah Mada, Jalan Grafika No. 2, Sleman, Yogyakarta 55281

ORCID: 0000-0003-3843-179X · OpenAlex: A5078494633

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Abstract

The objective of this study was to evaluate the effects of single-stage thermochemical pretreatment using sodium hydroxide (NaOH) and a double-stage pretreatment combining NaOH and hydrochloric acid (HCl) on the production of reducing sugars and total phenolic compounds (TPC). The influence of pretreatment duration (30–120 minutes) and solvent concentration (NaOH: 0.2–1 N; HCl: 0.05–0.4 N) at 100 °C was systematically investigated. The results showed that the double-stage pretreatment led to a higher yield of reducing sugars while maintaining relatively low TPC levels. Analysis of variance (ANOVA) revealed that, in the single-stage pretreatment, NaOH concentration had a more pronounced effect than treatment duration. Conversely, in the double-stage pretreatment, duration had a greater influence than HCl concentration. Overall, the double-stage pretreatment, involving NaOH-induced delignification followed by acid-catalyzed hydrolysis, offers a promising strategy for the efficient conversion of macroalgae into reducing sugars while minimizing phenolic compound accumulation.

Keywords

delignification; hydrolysis; macroalgae; pretreatment; thermochemical; double-stage

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Topics

Anaerobic Digestion and Biogas Production Primary

0.30

Building and Construction › Engineering › Physical Sciences

Seaweed-derived Bioactive Compounds

0.25

Biofuel production and bioconversion

0.15

Semantic Profile AI-classified research signals

Core Domains

Chemistry 0.83

level 0

Sodium hydroxide 0.72

level 2

Raw material 0.66

level 2

Secondary Topics

Yield (engineering) 0.53 Hydrochloric acid 0.49 Pulp and paper industry 0.41 Food science 0.38 Biogas 0.38 Lignin 0.37 Sodium 0.36 Solvent 0.36 Factorial experiment 0.36 Biomass (ecology) 0.33 Response surface methodology 0.31 Nuclear chemistry 0.29 Biofuel 0.27 Ethanol 0.26 Chromatography 0.25

Institution Network

Universitas Gadjah Mada ID
Elli Prastyo · Rochim Bakti Cahyono · Lisendra Marbelia · Wiratni Budhijanto

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