Optimization of Carbonization Process for the Production of Solid Biofuel from Corn Stalk Using Response Surface Methodology

Corn stalk is not suitable for direct combustion due to poor grindability, high moisture content, and insufficient heating value. The aim of this study was to optimize reaction conditions to improve the quality of corn stalk char, and to investigate the effects of carbonization on the physicochemical and combustion characteristics of corn stalks and chars. Optimal conditions for the carbonization of corn stalk were investigated with regard to temperature, holding time, and particle size. Response surface methodology (RSM) provided satisfactory models of responses, and the optimal conditions for higher heating values were obtained as follows: temperature of 551 °C, holding time of 150 min, and particle size range of 0.8–1.0 mm. In addition, after carbonization, changes in surface morphology, functional groups, and organic elements were clearly observed on the chars. The optimal point char experienced fairly complete carbonization, and holds promise for use as a solid biofuel.