Investigation into the synergism and interaction for waste valorization via co-pyrolysis of milk packet and Parthenium hysterophorus through thermogravimetric analysis

Abstract

Co-pyrolyzing mixed wastes with varying physicochemical properties can be quite challenging. This study reports on the pyrolysis and co-pyrolysis of low-density polyethylene collected in the form of a milk packet (MP) and Parthenium hysterophorus (PH) biomass, and their mixture at various weight ratios, named as (MP9PH1, MP7PH3, MP5PH5, and MP3PH7). The physicochemical characteristics, thermal behavior, synergetic effects, and kinetic parameters of the selected feedstock and their mixture were analyzed using the thermal gravimetric (TGA) technique. The co-pyrolysis experiment was conducted in an inert environment (N _2 ) using different heating rates of 10, 20, and 30 K min ^−1 , in a TG analyzer that ranged from 303 to 1173 K min ^−1 . The activation energy ( E _a ) for the co-pyrolysis of MP and PH mixtures was determined by using TGA data and applying iso-conversional model-free techniques such as Friedman and Kissinger–Akahira–Sunose. The kinetic analysis demonstrated that MP5PH5 sample needed 20%–26% lower activation energy to initiate the reaction of about 121–134 kJ mole ^−1 , whereas individual MP and PH required higher activation energy of about 150–203 kJ mole ^−1 . Additionally, the lower activation energy was also supported by the synergistic effect observed in MP5PH5 samples, which revealed the reduction of maximum degradation temperature, and more weight loss occurred due to higher interaction between reactive radicals generated from PH biomass and MP polymer during co-pyrolysis in comparison to other mixtures. These results demonstrate the advantages of using co-pyrolysis techniques over individual biomass for the valorization of waste.

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