Microwave-synthesised hydrothermal co-pyrolysis of oil palm empty fruit bunch with plastic wastes from Nigeria

Abstract

Microwave-assisted hydrothermal co-pyrolysis of biomass (oil palm empty fruit bunch) and plastic waste from sachet-water (widely available in Nigeria) was studied to improve the yield and quality of bio-oil. The experiment was carried out in a customised microwave system under a maximum microwave power of 300 W, using a coconut shell-based susceptor. Further, the hydrothermal process was optimised using Box–Behnken design. The optimum conditions at which the highest bio-oil yield (66.7 wt%) was obtained were determined to be a temperature of about 380 °C, a sachet-water plastic ratio of 49 wt%, and a carrier gas flow rate of 1500 mL/min. Major chemical compounds found (by gas chromatography–mass spectrometry) in the aqueous phase of the bio-oil were alkane (decane), 3.7% and phenol, 84.9% with methoxyphenyl, 2.5% and ethanone, 8.9%. Aliphatic hydrocarbons (22.7%), monoaromatic (15.3%) and polycyclic (9.16%) aromatic hydrocarbons, linear oxygenates (2.1%), furan derivatives (2.3%), phenol derivatives (15.84%) and other compounds such as derivatives of cyclopentanones and pyran were found in the organic phase of the bio-oil which constituted 39.7% of the bio-oil fraction. Aqueous pre-treatment of the sample with deionised water under microwaves enhanced selectivity and produced bio-oil with optimum phenolic compounds (84.9%) in the aqueous bio-oil.

Keywords:

• Biomass
• plastic
• co-pyrolysis
• bio-oil
• Box–Behnken design

Acknowledgements

The authors are thankful to the Centre for Energy and Environmental Strategy Research of Kaduna State University, Nigeria for their support of this work.

Disclosure statement

No potential conflict of interest was reported by the authors.