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1. Full name: Nguyen Thi Kim Dung
2. Sex: Female
3. Date of birth: August 6th 1965
4. Place of birth: Hai Phong
5. Admission decision number: 1896/SĐH, 2007
6. Changes in academic process: No
7. Official thesis title: Investigation of arsenic, manganese and iron contamination in water environment under influence of the reduction-oxidation conditions and application for in-situ treatment of these contaminants.
8. Major: Environmental chemistry
9. Code: 62 44 41 01
10. Supervisors: 1. Ass.Prof., Dr. Tran Hong Con
2. Ass.Prof., Dr. Bui Duy Cam
11. Summary of the new findings of the thesis:
a. The oxidation ability of dissolved oxygen in oxidation process of As(III) into As(V) in water media and the influence of environmental parameters were studied and evaluated. In distilled water there was only arsenic, the oxidation ability of oxygen was quite low; only about 30% As(III) oxidized into As(V) at equilibrium (30 min). The presence of iron and manganese can foster the oxidation process almost As(III) converted to As(V) in the same conditions (about 95%). Whereas, in water medium which has compositions similar rain water, the oxidation of Ar(III) into As(V) and Mn(II) into Mn(IV) (MnO2 ) were decreased.
b. In water media, the removal of arsenic and manganese depends on pH, iron(III) hydroxide formations and other interfering ions, especially phosphate and silicate. The amorphous iron(III) hydroxide has high arsenic adsorption. In the proportion of amorphous iron(III) hydroxide of 48.6% (in solution containing initial Fe(II) concentration of 30 mg/L) more than 95% arsenic was removed. However, the microcrystal species of iron(III) hydroxide has also adsorbed arsenic, but it was lower. The effect of iron(III) hydroxide on manganese removal was negligible. The removal of manganese was mainly by oxidation of Mn(II) into insoluble MnO2.
c. Designed and set up the simple research system imitated natural weathering and anaerobic conditions. The results showed cleared general observations of arsenic, manganese, iron species transformation and interaction between themselves and other components in and between water – solid phase.
d. Reviled and explained the transformation of arsenic(III) into insoluble arsenide in deep anaerobic condition.
e. Proposed the solutions for arsenic, manganese and iron fixation in the aquifer during ground water exploitation to reduce arsenic, manganese and iron concentration in underground water to meet with the permitted level for supply water.
12. Practical applicability, if any:
The results of the thesis provided background information to help scientists, managers and governors to consider and establish plans for arsenic, manganese and iron treatment in underground water or to localize contaminated areas and to control the risk to human health.
13. Further research directions, if any:
a. To continue research on arsenic and manganese contamination in water environment, their behaviors, transformation mechanism and treatment.
b. To expand research on the field of arsenic contamination localization based on the ORP values, iron species concentration and other indicators.
c. To research on application of the idea of in site arsenic, manganese and iron fixation.
14. Thesis-related publications:
[1] Nguyen Thi Kim Dung, Bui Duy Cam, Tran Hong Con (2009), "Investigation of influence of basic parameters in groundwater on co-precipitation – adsorption of arsenic, manganese and fresh iron(III) hydroxide", Journal of Analytical Science, Vol.14 (No.1), pp.40-45.
[2] Nguyen Thi Kim Dung, Bui Duy Cam, Tran Hong Con (2010), "Investigation of influencing factors in releasing process of arsenic, manganese and iron from their minerals into water", Journal of Analytical Science, Vol.15 (No.3), pp.200-204.
[3] Nguyen Thi Kim Dung, Bui Duy Cam, Tran Hong Con, Le Manh Cuong (2010), “Investigation of influencing factors in releasing process of arsenic, manganese and iron from their minerals into water environment in anaerobic conditions on simulation device”, Journal of Chemistry, Vol.48, pp.390-395
[4] Nguyen Thi Kim Dung, Bui Duy Cam, Tran Hong Con (2011), "Investigation of arsenic, manganese and iron releasing process from their minerals into water environment in anaerobic conditions", Journal of Chemistry, Vol.48, pp.725-731.
[5] Nguyen Thi Kim Dung, Bui Duy Cam, Tran Hong Con, Yumei Kang (2011), "Investigation of arsenic, manganese and iron fixation on side of a aquifer in order to remove them during groundwater exploitation", Environmental Geochemistry and Heath, ISSN 0269 – 4042DOI 10.1007/s 10653 – 011 – 9401 – 7.
[6] Nguyen Thi Kim Dung, Bui Duy Cam, Tran Hong Con (2011), “ Investigation of influencing factors on releasing process of arsenic, manganese and iron from minerals containing arsenide to water environment ”, Environment Asia, Vol.4 (No.2), pp.43-49 .
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