Study on the Mechanism of Photocatalytic Degradation of Poly(α-olefin)†

doi:10.7503/cjcu20150660

Abstract

Abstract:

Poly(α-olefin)(PAO, commonly used rolling base oil) attached to the surface of copper foil was degradated using photocatalytic microreactor. The chemical state, free radical and functional groups during the degradation process were detected by X-ray photoelectron spectroscopy(XPS), electron spin resonance spectroscopy(ESR) and Fourier transform infrared spectroscopy(FTIR). At last, the photocatalytic degradation mechanism was discussed. The results show that the introduction of oxygen groups and the CO₂ desorption exist in the degradation process and the main free radical is hydroxyl radical(·OH). The degradation process is accompanied with the increase of —OH and the decrease of C—H bond. In the process of photocatalytic degradation of PAO, ·OH attacking polymer is from the beginning of substitution reaction, firstly, ·OH substituted the hydrogen atom of methyl group, then the formed —OH changes to carboxyl and aldehyde, and then small organic molecules are formed. This process continues and the polymer molecular chain become shorter and shorter and produce only CO₂, H₂O and other inorganic substances at last.

Key words: Poly(α-olefin)(PAO), Free radical, Functional group, Degradation mechanism

CLC Number:

O644

TrendMD:

PENG Zhannan, LIU Xuefeng, LIN Guanqun. Study on the Mechanism of Photocatalytic Degradation of Poly(α-olefin)^†[J]. Chem. J. Chinese Universities, 2016, 37(2): 316.

Figures/Tables 5

Fig.1 SEM image(A) and XRD pattern(B) of nanometer TiO2 thin film

Fig.2 Elemental atomic concentration before() and after() the photocatalytic degradation

Fig.3 High resolution XPS spectra of C1s(A, C) and O1s(B, D) before(A, B) and after(C, D) photocatalytic degradation

Fig.4 ESR spectrum of stable free radical formed by PAO

Fig.5 FTIR spectra of —OH(A, B) and —CH2(C) at different degradation time Time/h: a. 0; b. 1; c. 3; d. 6; e. 10.

References 17

[1]	Cai R., Hashimoto K., Itoh K., Kubota Y., Fujishima A., Bull. Chem. Soc. Jpn., 1991, 64(4), 1268—1273
[2]	Cai R., Hashimoto K., Kubota Y., Fujishima A., Chem. Lett., 1992, 243(3), 427—430
[3]	Ju Y.C., Studies on Lubricity, Ecotoxicity of Environmental Friendly Lubricant and Evaluating Techniques, Tianjin University, Tianjin, 2003
	(居荫诚. 环境友好润滑油润滑性、生物毒性及其评定技术的研究, 天津: 天津大学, 2003)
[4]	Wang B., Lubrication and Application Properties of Two New Environmental Friendly Lubricants, Shanghai University, Shanghai, 2005
	(王彬. 两种新型环境友好润滑剂及其润滑性和应用性研究, 上海: 上海大学, 2005)
[5]	Goswami D. Y., J. Sol. Energy Eng., 1997, 119(2), 101—107
[6]	Linsebigler A. L., Lu G. Q., Yates J. T. Jr., Chem. Rev., 1995, 95(3), 735—758
[7]	Oda K., Ishizaka Y., Sato T., Eitoku T., Katayama K., Anal. Sci., 2010, 26(9), 969—972
[8]	Chen J. T., Li X. J., Yang Y., Wang L. Y., He M. X., Chinese J. Catal., 2004, 25(5), 397—402
	(陈俊涛, 李新军, 杨莹, 王良焱, 何明兴. 催化学报, 2004, 25(5), 397—402)
[9]	Wang W., Yuan Q., Chi Y., Shao C. L., Li N., Li X. T., Chem. Res. Chinese Universities, 2012, 28(4), 727—731
[10]	Briggs D., Surface Analysis of Polymers by XPS and Static SIMS, Cambridge University Press, New York, 1998, 27—46
[11]	Zhang Y. W., Tian J. Q., Li H. Y., Wang L., Qin X. Y., Asiri A. M., Al-Youbi A. O., Sun X. P., Langmuir, 2012, 28(35), 12893—12900
[12]	Martínez J. M. L., Rodríguez-Castellón E., Sánchez R. M. T., Denaday L.R., Buldain G. Y., Dall’Orto V. C., J. Mol. Catal. A: Chem., 2011, 339(1), 43—51
[13]	Qiu Z.W., Electron Spin Resonance Spectroscopy, Science Press, Beijing, 1980, 54—56
	(裘祖文. 电子自旋共振波谱, 北京: 科学出版社, 1980, 54—56)
[14]	Livngiston R., Zeldes H., J. Chem. Phys., 1966, 44(3), 1245—1259
[15]	Cheng X.R., Electron Spin Resonance Experiment Technology, Science Press, Beijing, 1986, 43
	(陈贤熔. 电子自旋共振实验技术, 北京: 科学出版社, 1986, 43)
[16]	Wang X., Li L., Chen N., Wang Q., Chem. J. Chinese Universities, 2012, 33(4), 813—817
	(王郗, 李莉, 陈宁, 王琪. 高等学校化学学报, 2012, 33(4), 813—817)
[17]	Wang D. D., Liu J. B., Chang H. B., Tang S. S., Chem. J. Chinese Universities, 2014, 35(9), 1975—1981
	(王丹丹, 刘俊渤, 常海波, 唐姗姗. 高等学校化学学报, 2014, 35(9), 1975—1981)