Degradation of lignin model compounds using ambient-air glow discharge*

 Lignin is a persistent polymer and needs to be degraded to obtain bioethanol from woody materials. In this study, we propose an environmentally friendly method of degrading lignin using plasma. We developed an ambient-air glow discharge(AAGD). The AAGD was developed as atmospheric pressure plasma sources allowed treatments of various targets by reactive species not employing vacuum systems. In this study, we attempted to cleave the structure of a lignin model compound, guaiacyglycerol-β-guaiacyl ether (GGE), using AAGD. The GGE solution was treated using the AAGD plasma for 0, 2.5, 5, 7.5, and 10 min. The decomposition degrees of GGE samples using the AAGD were estimated using a high-performance liquid chromatography (HPLC) connected with a photodiode array (PDA) detector.

The GGE decomposition using the AAGD for 10 min was reduced by approximately 65 % comparing with that of untreated GGE samples. Moreover, a new peak was detected at the retention time of 0.5 min, and the peak area gradually increased as the irradiation time increased. From these results, it is speculated that the AAGD irradiation has a great potential for efficient decomposition of lignin to enhance bioethanol production.