Thermal degradation kinetics of lignocellulosic peach stone waste

Abstract

The decrease of fossil fuel resources as well as associated pollution induced by its applications has increased the interest in findings of renewable fuels from various biomasses such as wood, energy crops, and various waste disposed from agricultural and food-industry activities. Especially interesting is lignocellulosic waste (LCW) biomass, found in large quantities after processing of the raw biomass, which pose certain energetic properties that might be used to fulfil future sustainability demands. This paper describes the thermal decomposition of waste peach stones (PS) investigated via thermogravimetric (TG) analyses. TG/DTG analyses provided a set of experimental mass loss data (obtained under different conditions), which were modelled by different kinetic models, resulting in parameters that might be used for industrial application of the tested biofuel. The goal of analyzing the kinetics of thermal degradation was to establish a relationship between the rate of degradation, degree of conversion (α) and temperature. In this sense, the investigation of the kinetics of thermal degradation was performed in non-isothermal conditions, with the heating speed varying from 5 to 20 ºC/min in an oxygen stream. Activation energy (Ea) of the PS thermal degradation was determined using Flynn-Wall-Ozawa (FWO) isoconversional model free method. The possible reaction mechanism that controls the process was investigated by the method of Coats- Redfern (C-R). The values of the Ea obtained by this method were not constant with the change in the degree of conversion (α), indicating that the thermal decomposition of PS represents a complex process that cannot be described by a one-step reaction in the entire range of conversions. PS waste samples investigated in this paper, have certain physical and chemical properties which satisfy request for energy density, small ash content and safe burn out. Presented results might support the value of biowaste in a future circular bio economy of Serbia.