Applications of isoconversional kinetic analysis to evaluate pyrolytic behavior of phytoremediation biomass

Phytoremediation plants are important species in sustainable management of polluted environments. These plants generate large amounts of contaminated biomass waste after harvesting. In this regard several studies have been conducted on the valorization, and degradation kinetics of biomass sources ranging from energy crops to industrial waste. Here we present a comparative study of the non-isothermal degradation kinetics of pristine and phytoremediation biomass of Cyperus papyrus and Phragmites australis with the aim of evaluating the influence of heavy metal loading on the pyrolysis activation energy and hence energy impacts for pyrolyzing phytoremediation biomass. The kinetic behaviour of pristine and phytoremediation Cyperus papyrus and Phragmites australis biomass, was successfully studied through thermogravimetric analysis. The analysis was performed at different heating rates (10–30 °C/min) in an inert atmosphere at temperatures from 25 to 700 °C. Activation energy, a fundamental parameter of chemical kinetics, was calculated using three iso-conversional kinetic models: Friedman, Starink, and Vyazovkin models across a range of conversion degrees (α = 0.15–0.80). The activation energies from the methods utilised in this study ranged from 118 to 260 kJ/mol. The lowering of activation energies for phytoremediation Cyperus papyrus suggests that phytoremediation does not negatively impact the energy cost of thermochemical valorization of the biomass. The most probable reaction mechanism (reaction model), the apparent activation energies and the preexponential frequency factors were determined using model fitting procedures making use of the Coats-Redfern method. This study provides fundamental primary data on the comparative study of non-phytoremediation and phytoremediation biomasses using non-isothermal methods. The results obtained highlight the possibility of thermochemical valorization of phytoremediation biomass without adverse implications on energy requirements