COLL 155 |
| Li Li, State Key Laboratory for Heavy Oil Processing, University of Petroleum, China, No 271, Bei'er Road, Dongying, 257061, China, Z.F. Yan, State Key Laboratory for Heavy Oil Processing, University of Petroleum, No 271, Bei'er Road, Dongying, 257061, China, and Xiaoyi Zhang, Department of Chemistry, Guizhou Normal University, Guizhou Normal University ,China, Guiyang, 550001, China. |
| In this work, relationships between the molecular structure and biodegradation of some nonionic surfactants were investigated using a quantitative structure-biodegradation relationship approach. The biodegradation for some nonionic surfactants (C12EO2, C12EO4, C12EO5, C12EO6, C12EO9, and C12EO12) was explored by using shake culture test with an activated sludge system. The biodegradability results indicated that these compounds were readily degraded at 60ppm. The removal of six surfactants improved with decreasing number of ethoxy groups (EO) at the same alkyl chain (C12). The biodegradation of nonionic surfactants follows the distance principle. The electronic structure characteristics of these samples were considered with quantum chemical methods. The quantum-chemical descriptors were computed by using DFT method at the b3lyp//6-31g* and semiempirical quantum chemical method at the PM3 level. These descriptors include the total electronic energy ET, the energy of the highest occupied molecular orbit EHOMO , the energy of the lowest unoccupied molecular orbit ELUMO, the energy of ELMO(-C-O-) and ELMO(O), the net charges of oxygen at the ethoxy groups QO and carbon at the alkyl chain QC and the dipole moment ƒÝ.By combining the principal component analysis with the best multiple linear regression analysis together in the heuristic method, the multiple linear regression analysis between the surfactant molecular descriptors and biodegradation was carried out. The model indicated that biodegradation increases with the decrease of HOMO and LUMO orbital energy difference (£GE) and the increase of the total electronic energy ET. It has a good correlation coefficient of r2=0.99. Furthermore, the monadic linear regressions showed that the distribution charge has no effect on biodegradation. |
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Symposium in Memory of Arthur W. Adamson
2:00 PM-5:40 PM, Monday, March 29, 2004 Marriott -- Orange County 4, Oral
Division of Colloid and Surface Chemistry |