Characterization and Cu sorption properties of humic acid from the decomposition of rice straw
- 172 Downloads
Humic acid (HA) derived from rice straw decomposed for 1 (HA-1), 3 (HA-3), 6 (HA-6) and 12 (HA-12) months was characterized by potentiometric titration and solid-state cross-polarization magic-angle spinning 13C nuclear magnetic resonance spectroscopy (CPMAS 13C NMR). The sorption of Cu on examined HA was investigated using a combination of batch sorption, isothermal titration calorimetry (ITC) and sequential desorption. Results showed that the functional group content and the humification degree of HA tended to increase with increasing decomposition time especially in the latter stage of examined decomposition period. Cu sorption on HA was a rapid process that occurred within the first 1 h and the sorption capacity increased from 245.4 mmol kg−1 on HA-1 to 294.6 mmol kg−1 on HA-12. The sorption of Cu was endothermic, spontaneous and the randomness was increased during Cu sorption. Sorbed Cu on examined HA can be hardly released by NH4Ac but nearly fully released by EDTA. Forming inner-sphere complexes was the main mechanism of Cu sorption on examined HA. This study could provide valuable information for a better understanding on the environmental impacts of the decomposition of organic waste.
KeywordsSorption Cu Humic acid Decomposition Rice straw
We are grateful to the Natural Science Foundation of China (41201232), the China Agriculture Research System—Green Manure (CARS-22) and the Fundamental Research Funds for the Central Universities (Program number 2662017JC009) for the financial support on the research.
- Dou S (2002) Soil organic matter. Science Press, BeijingGoogle Scholar
- Herbelin AL, Westall JC (1999) FITEQL: a computer program for determination of chemical equilibrium constants from experimental data. Version 4.0, Department of Chemistry, Oregon State University, Corvallis, ORGoogle Scholar
- Nancollas GH (1996) Interactions in electrolyte solutions. Elsevier, Amsterdam, The NetherlandsGoogle Scholar
- Stevenson FJ (1994) Humus chemistry: genesis, composition, reactions. Wiley, New YorkGoogle Scholar
- Swift RS (1996) Organic matter characterization, in: Sparks DL, Page AL, Helmke PA, Loeppert RH, Soltanpour PN, Tabatabai MA, Johnston CT, Sumner ME (Eds.), Methods of soil analysis, part 3. Chemical methods, SSSA book series, no. 5, ASA and SSSA, Madison, WI, pp. 1011–1069Google Scholar
- Wang XD, Yu TF, Chen DR, Yin XQ (2001) Dynamic change of chemical composition of corn straw and humus acid during different decomposition periods I. The change of corn straw chemical composition. Agric Res Arid Areas 19:78–82 (in Chinese)Google Scholar