2014 Volume 93 Issue 11 Pages 1207-1212
The purpose of this study is to efficiently produce hydrogen gas from saccharide using 27.12 MHz radiofrequency (RF) in-liquid plasma with and without ultrasonic irradiation. The experiments were conducted adopting two different ultrasonic frequencies, one from a 29 kHz horn-type ultrasonic transducer and the other from a 1.6 MHz piezoelectric transducer. The glucose solution and cellulose suspension concentrations were varied from 0.5 wt% to 50 wt% and 0.5 wt% to 20 wt% respectively. Hydrogen gas was then produced by the decomposition of the glucose solution and cellulose suspension by RF in-liquid plasma with and without ultrasonic irradiation. The hydrogen production rate from glucose solution with ultrasonic irradiation applied was greater than that without ultrasonic irradiation. However, no hydrogen production rate enhancement was observed from decomposition of cellulose suspension with ultrasonic irradiation applied. Ultrasonic atomization and agitation enhanced the chemical reaction of nonvolatile glucose in in-liquid plasma. The increase of the gas production rate was caused by the direct decomposition of the glucose by the plasma due to the atomized glucose molecules being fed into the plasma in a bubble. In addition, by using a high-speed camera, it was clarified that acoustic streaming occurred when a 1.6 MHz piezoelectric transducer was used in the experiment.