Microwave co-pyrolysis of kitchen food waste and rice straw for waste reduction and sustainable biohydrogen production: Thermo-kinetic analysis and evolved gas analysis

Abstract

Physico-chemical characteristics of kitchen food waste (KFW) and rice straw (RS) were explored to determine the optimum feedstock ratio for biohydrogen production. An in-depth investigation on the thermogravimetric degradation was conducted at heating rates of 10, 20, and 30 ℃/min. Friedman, Kissinger-Akahira-Sunose, and Flynn-Wall-Ozawa iso-conversional techniques were applied to investigate the kinetic properties of different mass ratios of the feedstocks. The average apparent activation energy (Ea) increased for all co-pyrolysis blends, reaching a maximum for 75KFW blend samples (138.6911 kJ/mol for Friedman, 136.9028 kJ/mol for KAS, and 146.5558 kJ/mol for FWO). The relatively small difference between ΔH and Ea indicated the production feasibility of the reactions. A microwave reactor was used to investigate product yields for different blend proportions. Gas chromatography analysis showed that co-pyrolysis improved production of biohydrogen, with 25KFW attaining a maximum yield of 43.02%. Overall, this study reflects the viability of scaled-up KFW and RS co-pyrolysis as a waste management alternative and an effective and sustainable source of biohydrogen.