D.-E. Lin1, Y.-W. Zhang1, C.-H. Wei2
1 Department of Applied Chemistry
2 College of Chemical Engineering，South China University of Technology, Guangzhou, 510640, China
Key word: Polyhydroxyalkanoates; Biodegradable plastic; Activated sludge
Polyhydroxyalkanoates(PHAs) are Polyesters synthesized by numerous bacteria in sludge as intracellular carbon and energy storage compounds under the condition of unbalance growth. Another important aspect of PHAs is thermoplastic polyester with the remarkable characteristics of biodegradability. The possibility of PHAs production by activated sludge has been already demonstrated[3~5]. In order to research the relations of carbon sources to structure of PHAs, six kinds of PHAs sample were synthesized by activated sludge with six different carbon sources respectively in the aerobic-anaerobic-anoxic process. Their structures were determined by 1HNMR、13CNMR and GC-MS. The six different carbon sources is as following: 1# acetate; 2# propionate; 3# 80%butyrate and 20%1,4-butanediol; 4# 20%butyrate and 80%1,4-butanediol; 5# 60% pentanoate and 40%glucose; 6# 60% benzoate and 40% glucose. The result showed in table 1.
Table 1 Monomer ratio of PHAs production by activated sludge with different carbon sources
|
Carbon source |
Monomer ratio of PHAs /mol% | ||||||
|
HB1 |
HV2 |
2MHB3 |
2MHV4 |
4-HB5 |
4MHV6 |
HHx7 | |
|
1# |
93.91 |
6.09 |
|
|
|
|
|
|
2# |
28.66 |
63.13 |
2.55 |
5.66 |
|
|
|
|
3# |
65.03 |
28.06 |
1.91 |
2.69 |
0.73 |
0.78 |
0.80 |
|
4# |
61.39 |
23.01 |
4.58 |
5.97 |
0.91 |
2.37 |
1.77 |
|
5# |
41.24 |
58.76 |
|
|
|
|
|
|
6# |
65.48 |
34.52 |
|
|
|
|
|
1: 3-hydroxybutanoic acid; 2: 3-hydroxypentanoic acid; 3: 2-methy- 3-hydroxy- butanoic acid; 4: 2-methyl-3-hydroxy- pentanoic acid; 5: 4-butanoic acid; 6: 4-methyl- 3-hydroxy -pentanoic acid; 7: 3-hydroxyhexanoic acid
GPC analyst showed that molecular weight distribution of these four types of PHAs(extracted by sodium hypochlorite- chloroform method) were narrow, number molecular weight were 40000~70000, weight molecular weight were 50000~90000, molecular weight distribution were 1.1~1.4. TCA analyst showed that these six types of PHAs samples could be decomposed on the temperature 255~275℃. DSC analyst showed that fusion temperature and enthalpy fusion of these six types of PHAs changed with HV unit compositions and ratios.
We could not go into the details of the biochemical mechanism in this research, but we are sure that we have showed that PHAs obtained by activated sludge with different carbon sources composed of different monomer units, which would be expected as new biodegradable materials.
This study was supported by the Natural Science Foundation (foundation item: 50278036).
[1] Lee S. Y., 1996. Biotechnol. Bioeng. 49(1), 1-14.
[2] Satoh H, et al., 1998. Wat. Sci. Tech. 38(2), 103-109.
论文来源：International Symposium on Biological Polyesters ,Auguest 22-27, 2004
