Effect Of Decay On Chemical Composition Of Wood And Properties Of Activated Carbon

Decay is an inevitable process in nature, and it is of great significance in ecological system. Wood raw materials will unavoidably occur in different types, varying degrees of decay. A systematic study has been made on the influences of wood decay on chemical composition and properties of activated carbon in this thesis. The results from this study could provide reference for the scientific utilization of rotten wood resources.Qinghai Spruce(Picea crassifolia)was used in this study. Two fungi, Brown Rot [Gloeophyllum trabeum(Pers.) Murrill], Aspergillus niger were used for decay treatment of Qinghai spruce, the natural decay was as control. After decay treatment, the weight loss rate of specimen was checked; the changes of chemical composition of lignin, cellulose, hemicellulose, pectin, protein were analyzed. The chemical activation of the decayed samples was also carried out. The effect of decayed wood on the properties of activated carbon was preliminarily investigated as well.The properties of fresh spruce specimen were tested. The holocellulose content, cellulose content, hemicellulose content, lignin content, pentosan content, and content of 1 % NaOH extractive were 50.98 %, 45.20 %, 5.78 %, 28.00 %, 14.44 % and 13.20 % respectively in spruce branches, while the holocellulose content, cellulose content, hemicellulose content, lignin content, pentosan content, and content of 1 % NaOH extractive were 42.81 %, 6.67 %, 27.20 %, 13.54 % and 11.50 % respectively in spruce leaves.The holocellulose content, cellulose content, lignin content, pentosan content, and content of 1 % NaOH extractive of Qinghai spruce branches were 34.33 %, 17.96 %, 15.79 %, 53.01 %, and 62.47 % respectively after 84 days decay treatment by Brown rot, while the cellulose content, lignin content, pentosan content, and content of 1% NaOH extractive were 28.31 %, 16.95 %, 12.98 %, 44.97 % and 65.64 % respectively in spruce leaves. The results showed that the number of bacterial colonies increased with the increment of decay degree. The contents of holocellulose, cellulose, and lignin decreased while the pentosan content, and content of 1% NaOH extractive increased. The lignin degradation rate was slower than cellulose.The holocellulose content, cellulose content, lignin content, pentosan content, and content of 1% NaOH extractive of Qinghai spruce branches were 30.89 %, 21.11 %, 9.79 %, 35.52 %, and 42.47 % respectively after 84 days decay treatment by Aspergillus niger, while the cellulose content, hemicellulose content, lignin content, pentosan content, and content of 1% NaOH extractive were 30.01 %, 20.87 %, 6.99 %, 31.54 % and 31.64 % respectively in spruce leaves. The results showed that the contents of holocellulose, hemicellulose, and lignin decreased while the pentosan content, and content of 1% NaOH extractive increased. Unlike Brown rot treatment, the lignin degradation rate was faster than cellulose under decay treatment by Aspergillus niger.The holocellulose content, cellulose content, lignin content, pentosan content, and content of 1% NaOH extractive of Qinghai spruce branches were 39.29 %, 28.85 %, 19.23 %, 11.28 %, and 42.56 % respectively after 12 months of natural decay treatment by Brown rot, while the holocellulose content, cellulose content, lignin content, pentosan content, and content of 1% NaOH extractive were 31.92 %, 25.66 %, 16.21 %, 6.99 % and 42.49 % respectively in spruce leaves. The results showed that the pentosan content decreased, while the content of 1% NaOH extractive increased.The pentosan content, and content of 1% NaOH extractive of Qinghai spruce specimen increased under treatment no matter by Brown rot or by Aspergillus niger. The pentosan content of decayed branches was up to 53.01(>18 %), it could be used as raw material for production of furfuraldehyde, which has a great economic significance for utilizing decayed plant.Qinghai spruce branches were used as raw material and phosphoric acid method was utilized to investigate the effect of decayed wood on the properties of activated carbon. When the fixed activation temperature was set at 600 ℃, activation time was 1 hour, and the ratio of phosphoric acid to wood material by weight was 3 to 1, the activated carbon recovery rate from natural decay Qinghai spruce was from 39.6% to 41.7%, the iodine sorption value was from 813.2 mg/g to 916.6 mg/g, the methylene blue adsorption was various from 13.2 mL/0.1 g to 15.1 mL/0.1 g, the specific surface area was from 982.7 m2/g to 1132.9 m2/g, the specific pore volume was 1.7964 cm3/g to 1.9642 cm3/g. The activated carbon recovery rate from decayed Qinghai spruce by Brown rot was from 38.7% to 42.3 %, the iodine sorption value was from 713.4 mg/g to 916.7 mg/g, the methylene blue adsorption was various from 13.2 mL/0.1 g to 14.6 mL/0.1 g, the specific surface area was from 823.5 m2/g to 1132.9 m2/g, the specific pore volume was 1.8998 cm3/g to 2.0324 cm3/g. The above results indicated that the decayed wood raw material could be used to make activated carbon products. The decayed wood didn’t affect activated carbon yield much. The number of activated carbon pores increased with the degradation degree of decayed wood by Brown rot, which might result from increment of relative lignin content. This experimental results had certain practical significance for controlling the properties of products by controlling raw materials.