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Laboratory tests for efficient nitrate removal with water-washed zero valent iron and the associated mixed mediums

100%

Li F. , Chen X. , Liu C. , Guan Q. , Yuan Y.

Polish Journal of Environmental Studies

2019

tom 28

nr 3

The acid pre-washing of zero valent iron for improving removal efficiency would deduce the secondary pollution in groundwater, and more fine particles of zero valent iron would reduce the permeability of aquifers. In order to better understand the approaches of nitrate removal, a series of laboratory experiments was conducted in this study. Batch tests showed that washed zero valent iron powder and activated carbon are more efficient for removing nitrate than cemarite and zeolite, similar with the acid pre-washing zero valent iron. X-ray diffraction phase analysis showed that a kind of oxide Fe₃O₄ generated on the surface of the washed iron powder particles, which is mixed with Fe₂O₃ and FeO, is relatively loose and can improve the efficiency of nitrate removal. A continuous flow column system test showed that the coarse sand-zero valent iron mix (R1), the coarse sand-zero valent iron-activated carbon mix (R4), and the coarse sand-zero valent iron-sawdust mix (R5) are more effective for reducing nitrate than the coarse sand-activated carbon mix (R2) and the coarse sand-sawdust mix (R3). Components such as NO₂-N and NH₄⁺-N would have environmental concerns as well. Further chemical analysis on the fluids from nitrate removal treatment indicates that R1 and R4 are the most effective and also environmentally friendly media for nitrate removal. This study showed that R1 and R4 media could be developed into a viable technology for the removal of nitrate in high concentration of polluted groundwater.

The effect of polyacrylic acid on the surface properties of calcite and fluorite aiming at their selective flotation

72%

Zhang C. , Gao Z. , Hu Y. , Sun W. , Tang H. , Yin Z. , He J. , Guan Q. , Zhu Y.

Physicochemical Problems of Mineral Processing

2018

tom Vol. 54, iss. 3

868--877

In this study, the polyacrylic acid (PAA) was studied as a selective depressant for calcite in the selective flotation of fluorite and calcite, and the implications of this process for the separation of fluorite ore were studied using micro-flotation tests, and the results were analyzed with Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) analyses. The flotation tests indicated that the preferential adsorption of PAA onto calcite rather than sodium oleate (NaOl) could selectively depress the flotation of calcite, allowing its separation from fluorite at pH 7. The zeta potential of calcite became more negative with the addition of PAA rather than with NaOl. However, the characteristic features of PAA adsorption were not observed for fluorite, suggesting that NaOl preferentially adsorbed on the surface of fluorite, or that PAA could be replaced by NaOl on the fluorite surface. FT-IR and XPS analysis were utilized to obtain a better understanding of the mechanism by which PAA was more strongly adsorbed on the calcite surface than NaOl. This was revealed to occur through chemical bonding between the carboxyl group of PAA and the hydroxyl groups of the Ca species on the calcite surface, modifying the structure of the adsorbed layer. A possible adsorption mechanism, along with a postulated adsorption mode for the surface interaction between PAA and calcite, is proposed.

Comprehensive genomic analysis and expression profiling of Argonaute gene family and examination of their regulatory roles in water-use efficiency and abiotic stress responses in apple

72%

Zhou S. , Ma S. , Li M. , Li C. , Gong X. , Guan Q. , Tan Y. , Shao Y. , Li C. , Ma F.

Acta Physiologiae Plantarum

2016

tom 38

nr 09

Green ultrasound-assisted extraction of anthocyanin and phenolic compounds from purple sweet potato using response surface methodology

72%

Zhu Z. , Guan Q. , Guo Y. , He J. , Liu G. , Li S. , Barba F. J. , Jaffrin M. Y.

nr 1