Title Page
Abstract
Contents
1. Introduction 12
1.1. Background 12
1.2. Literature review 14
1.3. Research objectives 16
2. Materials and method 17
2.1. Quantification of polysulfide concentration in CPS 17
2.2. Production of artificially contaminated solution & CPS injection batch 20
2.3. Effect of iron(II) in heavy metal precipitation by CPS 22
2.4. Evaluation of effect of dissolved oxygen 23
2.4.1. Oxidation experiment of precipitates formed by CPS with DO 23
2.4.2. Cadmium sulfide oxidation by DO 23
2.5. Field applicability batch test 24
3. Results 26
3.1. Concentration of polysulfide in CPS 26
3.2. Deriving heavy metal precipitation mechanism by CPS 28
3.2.1. Single heavy metal contaminated solution (1) Cd2+[이미지참조] 28
3.2.1. Single heavy metal contaminated solution (2) Zn2+[이미지참조] 35
3.2.2. Complex heavy metal contaminated solution 42
3.3. Effect of Fe2+ in heavy metal precipitation by CPS[이미지참조] 48
3.4. Evaluation of effect of dissolved oxygen 50
3.4.1. Evaluation of oxidation of precipitates formed by CPS with DO 50
3.4.2. Evaluation of oxidation of CdS without elemental sulfur by DO 54
3.5. Field applicability test for CPS 58
4. Conclusions 60
4.1. Precipitation mechanism of Cd2+ and Zn2+ by CPS[이미지참조] 60
(a) Heavy metal (Cd2+, Zn2+) precipitation by CPS[이미지참조] 60
(b) pH increase by residual polysulfide 61
4.2. Oxidation resistance of heavy metal precipitate from CPS 62
4.3. Field applicability test for CPS 63
5. Discussions 64
Reference 65
초록 69
Table. 2.1. Physicochemical properties of 29% (w/v) calcium polysulfide 17
Table. 2.2. Initial batch conditions before CPS injection 20
Table. 2.3. The heavy metal and the metal concentration in field groundwater for CPS injection batch test 24
Table. 2.4. The heavy metal and the metal concentration in field groundwater for oxidation experiment 25
Table. 3.1. Theoretical ME values calculated from CPS ME injection for a single heavy metal (a) Cd, Zn 1,000 mg/L (b) Cd, Zn 5,000 mg/L 43
Table. 3.2. Possible oxidation reactions of HS- by dissolved oxygen[이미지참조] 53
Figure. 2.1. The standard curve for HS- at 230 nm in 0.5 M borate buffer with pH 8.20[이미지참조] 18
Figure. 3.1. UV-Vis spectroscopy of CPS showing peak wavelength at around 230 nm 26
Figure. 3.2. XRD pattern for precipitate form from CPS (black) and S8 reference...[이미지참조] 27
Figure. 3.3. Removal (%) and pH change graph according to CPS injection ratio (Cd) 29
Figure. 3.4. Polysulfide (mM) vs Removed Cd (mM) 30
Figure. 3.5. XRD pattern of precipitate according to CPS injection (a) CPS/Cd2+ = 1.16 (b) CPS/Cd2+ = 1.45[이미지참조] 31
Figure. 3.6. SEM image, EDS mapping, and map sum spectrum of CPS/Cd2+ = 1.16 (gypsum & CdS)[이미지참조] 32
Figure. 3.7. SEM image, EDS mapping, and map sum spectrum of CPS/Cd2+ = 1.45 (CdS & S8)[이미지참조] 33
Figure. 3.8. SEM image of CPS/Cd2+ = 1.45 (gypsum)[이미지참조] 34
Figure. 3.9. Removal (%) and pH change graph according to CPS injection ratio (Zn) 35
Figure. 3.10. Polysulfide (mM) vs Removed Zn (mM) 36
Figure. 3.11. XRD pattern of precipitate according to CPS injection (a) CPS/Zn2+ = 2.00 (b) CPS/Zn2+ = 2.50[이미지참조] 37
Figure. 3.12. SEM image, EDS mapping, and map sum spectrum of CPS/Zn2+ = 2.00 (gypsum)[이미지참조] 38
Figure. 3.13. SEM image, EDS mapping, and map sum spectrum of CPS/Zn2+ = 2.00 (ZnS)[이미지참조] 39
Figure. 3.14. SEM image, EDS mapping, and map sum spectrum of CPS/Zn2+ = 2.50 (gypsum & ZnS)[이미지참조] 40
Figure. 3.15. SEM image, EDS mapping, and map sum spectrum of CPS/Zn2+ = 2.50 (S8)[이미지참조] 41
Figure. 3.16. Removal (%) and pH change graph according to CPS injection ratio (CdZn) (a) Cd, Zn 1,000 mg/L (b) Cd, Zn 5,000 mg/L 42
Figure. 3.17. XRD pattern of precipitate according to CPS injection (a) CPS 1.50% (b) CPS 2.00% 44
Figure. 3.18. SEM image, EDS mapping, and map sum spectrum of CPS 1.50% (gypsum & CdS & ZnS) 45
Figure. 3.19. SEM image, EDS mapping, and map sum spectrum of CPS 2.00% (gypsum) 46
Figure. 3.20. SEM image, EDS mapping, and map sum spectrum of CPS 2.00% (CdS & ZnS & S8) 47
Figure. 3.21. Removal (%) and pH change graph according to Fe2+ concentration (a) Cd (b) Zn (c) Cd, Zn (d) removed heavy metal (mM)[이미지참조] 49
Figure. 3.22. pH, and DO change of CPS/Cd2+ = 1.45 sample after CPS injection and exposed to atmosphere (a) 0 ~ 49 days (b) 0 ~ 2 days[이미지참조] 50
Figure. 3.23. pH, and DO change of CPS/Zn2+ = 2.50 sample after CPS injection and exposed to atmosphere (a) 0 ~ 49 days (b) 0 ~ 2 days[이미지참조] 51
Figure. 3.24. Concentration of different sulfide and polysulfide species in 50 mM K2S5 as a function of pH[이미지참조] 52
Figure. 3.25. Cd2+ concentration and pH change in CdS solid-water mixture as a function of time[이미지참조] 54
Figure. 3.26. Cd2+ concentration and pH change in CdS S8-water mixture as a function of time[이미지참조] 55
Figure. 3.27. (a) SEM image, EDS mapping, and map sum spectrum of elemental sulfur from CPS 56
Figure. 3.27. (b) SEM image, EDS mapping, and map sum spectrum of elemental sulfur from CPS 57
Figure. 3.28. Concentration and pH change of the contaminated groundwater with heavy metals and metals as a function of... 58
Figure. 3.29. pH, and DO change of contaminated groundwater after CPS injection and exposed to atmosphere (~21 days) 59