Working Volume in High-Energy Ball-Milling Process on Breakage Characteristics and Adsorption Performance of Rice Straw Ash

The purpose of this study was to investigate the effect of working volume in the high-energy ball-milling process on the breakage characteristics (i.e., particle size, morphology, and chemical composition) and adsorption performance of rice straw ash. This study was conducted to confirm working volume issue since this parameter has correlations with the scaling-up process, the amount of input/output in the ball-milling process, and the breakage characteristics of the material. Rice straw ash was selected as a model of size-destructed material because this material is porous and chemically and thermally inert; thus, the evaluation can be effectively done without any chemical reaction and time-consuming process. To obtain the outcome precisely, the study varied working volume under constant other processing parameters (i.e., ball-to-rice straw ash, milling speed/rotation, temperature, ball size) in the batch-typed conventional ball-milling process. The results showed that the ball-milling process is effective to reduce particle sizes to several micrometers and further nanometers. Precise control of the final particle size was achieved by the adjustment of working volume, in which the less working volume results in the generation of smaller particles. The prospect control of final particle size is due to the control of shear stress and collision phenomena during the ball-milling process. The evaluation was also completed with theoretical approximation and adsorption performance of the product. In addition to varying working volume, this study examined the product yield since it can be a contributive factor to determine the optimum condition of the ball-milling process.