Surface Discoloration Analysis and Lignin Degradation Fragments Identification of UV-Irradiated Moso Bamboo (Phyllostachys pubescens Mazel)

Haixia Yu, Wenji Yu, Liu Yang, Chongrong Fang, Manping Xu

Abstract


Color changes caused by artificial UV radiation of Moso bamboo (Phyllostachys pubescens Mazel) were recorded as a function of exposure time to obtain the maximum absorption trend by the Kubelka-Munk (K-M) spectra. Lignin photolysis into smaller molecules was evaluated using spectrophotometry and gas chromatography-mass spectrometry (GC-MS) analysis. Results showed that the K-M absorption peak increased in the yellow and red regions (360 to 500 nm) when compared with the untreated sample, which was in accordance with the yellow-red shift by visual observation. The maximum absorption of the K-M spectra from UVB phototreated bamboo was in the UV region. GC-MS analysis showed that benzene carbonyls, organic acid, and esters were the major types of photolysized molecules of bamboo lignin, which were derived from the C-C bonds adjacent to the α-carbonyl. UV irradiation (295 to 400 nm) resulted in the breakdown of carbonyl and unsaturated C-C groups conjugated to aromatic ring at the C., which partly contributed to the quick discoloration at the initial 100 h of UV irradiation.

Keywords


Bamboo; UV irradiation; Lignin; Photolysis; Kubelka–Munk; GC-MS

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