Accelerating the degradation of green plant waste with chemical decomposition agents

摘要

College of Resource and Environmental Sciences, South China Agriculture University, Guangzhou 510642, China ,Guangzhou Institute of Landscape Gardening, Guangzhou 510170, China;Guangzhou Institute of Landscape Gardening, Guangzhou 510170, China;Guangzhou Institute of Landscape Gardening, Guangzhou 510170, China;College of Resource and Environmental Sciences, South China Agriculture University, Guangzhou 510642, China ;Guangzhou Institute of Landscape Gardening, Guangzhou 510170, China;Guangzhou Institute of Landscape Gardening, Guangzhou 510170, China;%Degradation of green plant waste is often difficult, and excess maturity times are typically required. In this study, we used lignin, cellulose and hemicellulose assays; scanning electron microscopy; infrared spectrum analysis and X-ray diffraction analysis to investigate the effects of chemical decomposition agents on the lignocellulose content of green plant waste, its structure and major functional groups and the mechanism of accelerated degradation. Our results showed that adding chemical decomposition agents to Ficus microcarpa var. pusillifolia sawdust reduced the contents of lignin by 0.53%—11.48% and the contents of cellulose by 2.86%-7.71%, and increased the contents of hemicellulose by 2.92%-33.63% after 24 h. With increasing quantities of alkaline residue and sodium lignosulphonate, the lignin content decreased. Scanning electron microscopy showed that, after F. microcarpa var. pusillifolia sawdust was treated with chemical decomposition agents, lignocellulose tube wall thickness increased sig-nificantlylncreases of 29.41%, 3.53% and 34.71% were observed after treatment with NaOH, alkaline residue and sodium lignosulphonate, respectively. Infrared spectroscopy showed that C=O and aromatic skeleton stretching absorption peaks were weakened and the C-H vibrational absorption peak from out-of-plane in positions 2 and 6 (S units) (890-900 cm"1) was strengthened after F. microcarpa var. pusillifolia sawdust was treated with chemical decomposition agents, indicating a reduction in lignin content. Several absorption peaks [i.e., C-H deformations (asymmetry in methyl groups, -CH3- and -CH2-) (1450 -1460 cm"1); Aliphatic C-H stretching in methyl and phenol OH (1370-1380 cm"1); C=O stretching (cellulose and hemicellulose) (1040-1060 cm"1)] that indicate the presence of a chemical bond between lignin and cellulose was reduced, indicating that the chemical bond between lignin and cellulose had been partially broken. X-ray diffraction analysis showed that NaOH, alkaline residue and sodium lignosulphonate can reduce the relative crystallinity of lignocellulose in F. microcarpa var. pusillifolia by 2.64%, 13.24%, 12.44%, respectively. The C-H vibrational absorption peak from out-of-plane in positions 2 and 6 (S units) comes from the vibration of the sugar anomeric carbon. Because lignin is a phenolic, not carbohydrate polymer, the relative absorption intensity of this peak should be stronger at lower lignin contents. Compared to CK, the peak intensities increased in treatments Tl, T5 and T9, indicating reduced lignin contents and increased sugar contents after CDA treatment.