Analytical Pyrolysis Study of Peanut Shells using TG-MS Technique and Characterization for the Waste Peanut Shell Ash

Abstract

As an agricultural waste produced from the processing of peanut, the yield of peanut shells in China is quite abundant. Although numerous studies on the pyrolysis of peanut shells have been carried out, most of them were focused on the dynamics models for predicting kinetics parameter of biomass, and rarely on the evolution of gaseous products in pyrolysis. This study carried out a set of experiments on the pyrolysis of peanut shells under different heating rates in order to fill the knowledge gap. Besides, there is also a lack of information available concerning the characterization of resulting peanut shell ash. Thus, the aim of this study is to investigate the pyrolysis behaviors of peanut shells thoroughly and to characterize the properties of peanut shell ash that serves as predictors for its applications. The results show that the decomposition of peanut shells follows a stepwise mechanism, and the activation energy calculated by Flynn- Wall-Ozawa method varies from 58.3 to 88.6 kJ·mol–1. Compared with low heating rate, fast heating rate at low temperatures is more suitable for biogas production. Chemical and phase analysis shows that peanut shell ash has a high SiO2 content except for other oxides (K2O, CaO, MgO, Al2O3, etc.) that quite suitable in glass production, implying its potential for glass production and as a mineral admixture in concrete. Released volatile matters in pyrolysis create many pores in carbonaceous materials, thus low-cost adsorbents can be produced from these carbon residues.