Journal
JOURNAL OF ENVIRONMENTAL MANAGEMENT
Volume 275, Issue -, Pages -Publisher
ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD
DOI: 10.1016/j.jenvman.2020.111165
Keywords
Cr(VI) reduction; sodium borohydride; oxalate; Cr(III) precipitation; buffer
Categories
Funding
- Fundamental Research Funds for the Central Universities
- NSRIF [2020027]
- National Key R&D Program of China [2019YFD1100104]
- Reform of Graduate Teaching Research in Harbin Institute of Technology [JGYJ-2018029]
- Research on the undergraduate teaching reform of Harbin University of Technology [XJG-2017062]
Ask authors/readers for more resources
The method of treating high concentrations of Cr(VI) alone by NaBH4 has proved feasible, but the effects of the coexistence of Cr(VI) and organic compounds have not been evaluated. The objective of this study was to explore the potential mechanism by which oxalate affects the reduction of high concentrations of Cr(VI) treated by sodium bomhydride (NaBH4) and the subsequent precipitation of Cr(III). The results show that Cr(VI) reduction could be gradually promoted by oxalate (1.0-10 mM). Compared with the control solution, the reduction of Cr (VI) in a 10 mM oxalate solution could be increased from 56.6% to 99.1%. Particularly, the promotion of Cr(VI) reduction attributed to the enhancement of OH- production from NaBH4 hydrolysis due to the increasing concentration of C2O42- species, forming conjugated acid-base pairs in the form HC2O4-C2O42-, which provided an effective buffer. In 0.10-0.40 mM oxalate-Cr(VI)-NaBH4 systems, the resulting Cr(III) could precipitate at different levels within 20 h, and showed settlement rates in the range of 8.8% and 95.8%, but no precipitate was found in 1.0-10 mM oxalate-Cr-NaBH4 systems. This is related to whether there was a sufficient oxalate dosage, which could be complexed with Cr (III) at a molar ratio of 1:1. The precipitates were analysed by means of electron spin resonance (ESR), atomic force microscopy (AFM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR), indicating that Cr (III) could support oxalate coprecipitation. The results of the present study reveal the influence of oxalate on Cr(VI) reduction and subsequent Cr (III) precipitation, which are of great significance to the application of NaBH4 in the treatment of industrial wastewater containing Cr(VI)-oxalate.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available