Fe(III)-induced Sequestration of Citric Acid on Kaolinite Surface Probed by STXM-NEXAFS Spectroscopy
Received date: 2017-03-01
Online published: 2017-04-12
Supported by
Project supported by the Innovation Funds of the Chinese Academy of Agricultural Science for Overseas Elite Youth Program, and National Natural Science Foundation of China (Nos. 41601313, U1632134).
Organic carbon (OC) stability in tropical soils is strongly affected by the mutual interactions of OC, kaolinite and the Fe(Ⅲ) cation. Low molecular weight organic acids (LMWOAs) represent the most biodegradable constituent of OC in soils. Therefore, investigating retention mechanisms of LMWOAs in kaolinite-Fe(Ⅲ)-LMWOAs systems are of significant importance in understanding the sequestration and cycling of OC in tropical soils. However, retention mechanisms of LMWOAs in the kaolinite-Fe(Ⅲ)-LMWOAs system remains unclear, and there is a lack of direct evidence at the molecular level. In this study, citric acid (CA) was chosen as a model compound for LMWOAs and a sorption sample was collected after batch experiment using kaolinite, Fe(Ⅲ), and CA as reagents at pH 3.5 and at an initial Fe/CA molar ratio of 2.0. Synchrotron-based scanning transmission X-ray microspectroscopy (STXM) was applied to characterize the distribution of carbon (C), iron (Fe) and silicon (Si), representing CA, Fe(Ⅲ) cation/Fe hydroxides and kaolinite respectively, at the submicron scale in the sorption sample. After that, the hot spots of C and Fe were selected and further probed by STXM coupled with Near-edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy at the C and Si K-edge and the Fe L3-edge, respectively, to reveal the molecular structures of C, Si and Fe. Our results indicated the similar correlation of C-Fe (R2=0.965) to C-Si (R2=0.960) in the sorption sample, which implied a close relationship between CA and Fe hydroxides as well as kaolinite. We also found two Fe species as ferrihydrite and kaolinite-Fe(Ⅲ)-citrate complex coexisted in the Fe-enriched hot spots probed by STXM coupled with Fe L3-edge NEXAFS spectroscopy. These results provide direct evidence of the contribution of CA retention through ferrihydrite-induced adsorption/coprecipitation and ternary complexation of CA and kaolinite via an Fe bridge in the investigated ternary system. This study will enhance our understanding of the stability of CA and the sequestration and cycling of LMWOAs in tropical soils.
Key words： soil carbon sequestration; multivalent cation; STXM; NEXAFS; ferrihydrite
Liu Jina , Yang Jianjun , Zeng Xibai , Wang Jian , Donald Sparks . Fe(III)-induced Sequestration of Citric Acid on Kaolinite Surface Probed by STXM-NEXAFS Spectroscopy[J]. Acta Chimica Sinica, 2017 , 75(6) : 617 -620 . DOI: 10.6023/A17030082
[1] van Hees, P. A.; Jones, D. L.; Finlay, R.; Godbold, D. L.; Lundström, U. S. Soil Biol. Biochem. 2005, 37, 1.
[2] Van Hees, P.; Vinogradoff, S.; Edwards, A.; Godbold, D.; Jones, D. Soil Biol. Biochem. 2003, 35, 1015.
[3] Jagadamma, S.; Mayes, M.; Zinn, Y.; Gísladóttir, G.; Russell, A. Geoderma 2014, 213, 79.
[4] Turner, B. L. Appl. Environ. Microb. 2010, 76, 6485.
[5] Hens, M.; Merckx, R. Environ. Sci. Technol. 2001, 35, 493.
[6] Zhang, L.; Luo, L.; Zhang, S. Colloid. Surface A 2012, 406, 84.
[7] Ahmed, N.; Varadachari, C.; Ghosh, K. Soil Res. 2002, 40, 691.
[8] Jones, D. L. Plant Soil 1998, 205, 25.
[9] Kubicki, J.; Schroeter, L.; Itoh, M.; Nguyen, B.; Apitz, S. Geochim. Cosmochim. Acta 1999, 63, 2709.
[10] Manceau, A.; Marcus, M. A.; Tamura, N. Rev. Mineral. Geochem. 2002, 49, 341.
[11] Dong, M.; Wang, J. G.; Sun, Y. H.; Hu, T. D.; Liu, T.; Xie, Y. N. Acta Chim. Sinica 2000, 58, 1419. (董梅, 王建国, 孙予罕, 胡天斗, 刘涛, 谢亚宁, 化学学报, 2000, 58, 1419.)
[12] Hu, T. D.; Xiang, H. W.; Xie, Y. N.; Huang, D. X.; Chen, X. N.; Jin, Y. L.; Zhong, B.; Peng, S. Y. Acta Chim. Sinica 1995, 53, 1082. (胡天斗, 谢亚宁, 黄达贤, 陈贤能, 靳亚兰, 相宏伟, 钟炳, 彭少逸,化学学报, 1995, 53, 1082.)
[13] Yang, J.; Wang, J.; Pan, W.; Regier, T.; Hu, Y.; Rumpel, C.; Bolan, N.; Sparks, D. Sci. Rep. 2016, 6, 26127.
[14] Yang, J.; Liu, J.; Dynes, J. J.; Peak, D.; Regier, T.; Wang, J.; Zhu, S. H.; Shi, J.; Tse, J. S. Environ. Sci. Pollut. Res. 2014, 21, 2943.
[15] Wan, J.; Tyliszczak, T.; Tokunaga, T. K. Geochim. Cosmochim. Acta 2007, 71, 5439.
[16] Yeasmin, S.; Singh, B.; Kookana, R. S.; Farrell, M.; Sparks, D. L.; Johnston, C. T. J. Colloid Interf. Sci. 2014, 432, 246.
[17] Yang, J.; Regier, T.; Dynes, J. J.; Wang, J.; Shi, J.; Peak, D.; Zhao, Y.; Hu, T.; Chen, Y.; Tse, J. S. Anal. Chem. 2011, 83, 7856.
[18] Liu, X. R.; Eusterhues, K.; Thieme, J.; Ciobota, V.; Hoschen, C.; Mueller, C. W.; Kusel, K.; Kogel-Knabner, I.; Rosch, P.; Popp, J.; Totsche, K. U. Environ. Sci. Technol. 2013, 47, 3158.
[19] Eusterhues, K.; Rennert, T.; Knicker, H.; Kögel-Knabner, I.; Totsche, K. U.; Schwertmann, U. Environ. Sci. Technol. 2010, 45, 527.
[20] Saidy, A. R.; Smernik, R. J.; Baldock, J. A.; Kaiser, K.; Sanderman, J. Geoderma 2013, 209, 15.
[21] Solomon, D.; Lehmann, J.; Kinyangi, J.; Liang, B. Q.; Heymann, K.; Dathe, L.; Hanley, K.; Wirick, S.; Jacobsen, C. Soil Sci. Soc. Am. J. 2009, 73, 1817.
[22] de Groot, F. M. Inorg. Chim. Acta 2008, 361, 850.
/
| 〈 |
|
〉 |
