Reaktor
Volume 26 No.1 April 2026

Preparation of Bio-Oil and Biochar through Co-Pyrolysis of Pennisetum purpureum and HDPE Plastic Waste at Various Feedstock Ratios and Temperatures

Asfihani Asfihani (Universitas Malikussaleh)
Azhari Azhari (Universitas Malikussaleh)
Adi Setiawan (Mechanical Engineering Department, Faculty of Engineering, Universitas Malikussaleh, Jalan Batam, Bukit Indah, Lhokseumawe, 24352, Indonesia.)



Article Info

Publish Date
04 May 2026

Abstract

This study investigates the co-pyrolysis process of elephant grass (Pennisetum purpureum) and HDPE plastic waste and evaluates the properties of the resulting bio-oil and biochar. The process was conducted in a pilot-scale reactor under a nitrogen atmosphere using a two-stage heating scheme at 300°C and 450°C, with biomass–HDPE weight ratios of 100:0, 90:10, 75:25, 60:40, and 50:50. The method used in this work includes product yield analysis, thermophysical characterization, GC–MS-based chemical composition analysis, and ANOVA statistical validation to determine the optimum conditions for Pennisetum purpureum–HDPE co-pyrolysis process. The results indicate that the addition of HDPE does not increase the absolute yield of bio-oil but significantly enhances its energy quality. The calorific value of the bio-oil increased from 10,579 cal/g for pure biomass to a maximum of 12,029 cal/g at a 75:25 biomass–HDPE weight ratio, accompanied by a compositional shift from oxygenated compounds toward the dominance of fatty acid methyl esters (FAME) and medium- to long-chain hydrocarbons. At the same ratio, biochar achieved the highest yield (44.93% w/w) while maintaining characteristics suitable for energy applications. These findings identify the 75:25 biomass–HDPE ratio as the optimum condition based on both experimental and statistical evidence, and demonstrate that biomass–HDPE co-pyrolysis is an effective strategy for waste utilization and for enhancing the quality of renewable energy products.

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Journal Info

Abbrev

reaktor

Publisher

Subject

Chemical Engineering, Chemistry & Bioengineering Control & Systems Engineering Energy Materials Science & Nanotechnology

Description

Reaktor invites contributions of original and novel fundamental research. Reaktor publishes scientific study/ research papers, industrial problem solving related to Chemical Engineering field as well as review papers. The journal presents paper dealing with the topic related to Chemical Engineering ...