Comment on "Effects of particle size and coating on decomposition of alumina-extracted residue from high-alumina fly ash": Proposition of the shrinking cylinder model

The shrinking unreacted core model has been one of the most widely used models for the uncatalyzed reaction kinetics between the liquid/gas and the solid phases. However, the classical shrinking unreacted core model (CSUC model) is only applicable to spherical particles. Currently, the CSUC model has been used in many studies regardless of its applicable conditions. For example, Wang et al. (2016) investigated the decomposition kinetics of a rod-like residue and deduced the rate-controlling step using the CSUC model. The purpose of this comment is to propose a modified shrinking unreacted core model (shrinking cylinder model) suitable for materials with a high aspect ratio. The authors hope that this work will be helpful for kinetic analysis of rod-shaped and fiber-shaped materials in the uncatalyzed liquid/gas-solid reactions.