Title Page
ABSTRACT
Contents
CHAPTER 1. INTRODUCTION 12
1.1. Theoretical Background 12
1.2. Literature Review 17
1.2.1. Persulfate activation by carbocatalysts 17
1.2.2. Carbon materials with metal particles 19
1.2.3. Association between metal and carbon phase transformation 21
1.2.4. Manganese utilization for persulfate activation 23
1.3. Objectives 24
CHAPTER 2. MATERIALS AND METHODS 26
2.1. Reagents 26
2.2. Catalyst preparation 28
2.3. Catalyst characterization 29
2.4. Experimental procedure and analytical methods 30
CHAPTER 3. RESULTS AND DISCUSSION 32
3.1. Characterization of Mn/carbon composites 32
3.2. Persulfate activation capability of Mn-N-C 37
3.3. Effects of reaction parameters 42
3.4. Mechanisms variable dependent on the type of Mn-based materials 46
3.5. Identification of non-radical degradative pathways 53
3.6. Catalytic performance: Repetition test 57
CHAPTER 4. CONCLUSION 60
APPENDIX 62
REFERENCES 67
Table 1. Chemical and physical properties of PMS and PDS. 14
Table 2. Pristine carbon materials activated PDS and PMS for the degradation of organic contaminants. 18
Table 3. Activated of persulfates by carbon materials supported with metal. 20
Table 4. TEM map sum spectrum. 34
Figure 1. Oxidation mechanisms of persulfate activation. 16
Figure 2. SEM images of (a) unwashed 1 M Mn-N-C, (b) unwashed 2.36 M Mn-N-C, (c) unwashed 3 M Mn-N-C, (d) washed 1 M Mn-N-C, (e) washed 2.36 M Mn-N-... 33
Figure 3. TEM images of (a) washed 1 M Mn-N-C, (b) washed 2.36 M Mn-N-C and (c) washed 3 M Mn-N-C. 34
Figure 4. (a) Diffraction patterns, and (b) Mn2p XPS spectra of unwashed Mn-N-C and washed Mn-N-C. 35
Figure 5. N1s, C1s, Mn2p XPS spectra of 1 M, 2 M, 3 M Mn-N-C, respectively. 36
Figure 6. 4-CP degradation by manganese species catalysts ([Mn(II)]₀=0.1 mM; [MnO₂]₀=0.4 g/L; [Mn-g-C₃N₄]₀=0.1 g/L; [Mn-N-C]₀=0.05 g/L; [4-CP]₀=0.1... 38
Figure 7. 4-CP degradation by only PMS and PDS ([4-CP]₀=0.1 mM; [Persulfate]₀=2 mM; [Phosphate buffer]₀=1 mM; pHi=7.0).[이미지참조] 39
Figure 8. 4-CP degradation by carbon-based catalysts ([SWCNTs]₀=0.1 g/L; [Graphene]₀=0.1 g/L; [Mn-N-C]₀=0.05 g/L; [4-CP]₀=0.1 mM; [Persulfate]₀=2... 40
Figure 9. 4-CP degradation by Manganese-based catalysts ([Mn(II)]₀=0.1 mM; [MnO₂]₀=0.4 g/L; [Mn-N-C]₀=0.05 g/L; [4-CP]₀=0.1 mM; [PDS]₀=2 mM;... 41
Figure 10. 4-CP degradation in different initial loading of Mn-N-C and dosage of Persulfate ([4-CP]₀=0.1 mM; [Phosphate buffer]₀=1 mM; pHi=7.0).[이미지참조] 43
Figure 11. Zeta potential of Mn-N-C as a function of pH. 44
Figure 12. 4-CP degradation in different pH (a) Mn-N-C/PMS and (b) Mn-N-C/PDS system ([Mn-N-C]₀=0.05 g/L; [4-CP]₀=0.1 mM; [Persulfate]₀=2 mM; [Phosphate... 45
Figure 13. Degradation of 4-CP in Mn-N-C/Persulfate systems and scavenging effect of alcohols ([Mn-N-C]₀=0.05 g/L; [4-CP]₀=0.1 mM; [Persulfate]₀=2 mM;... 48
Figure 14. EPR spectra produced in the aqueous suspensions containing activators, persulfate and BMPO (spin-trapping agent). EPR signals were recorded 2 min after... 49
Figure 15. Degradation of multiple organic compounds by (a) Mn-N-C/PMS and (b) Mn-N-C/PDS system ([Mn-N-C]₀=0.05 g/L; [Organic compound]₀=0.1 mM;... 50
Figure 16. Degradation of multiple organic compounds by MnO₂/PMS system ([MnO₂]₀=0.4 g/L; [Organic compound]₀=0.1 mM; [PMS]₀=2 mM; [Phosphate... 51
Figure 17. Degradation of multiple organic compounds by Mn(II)/PMS system ([Mn(II)]₀=0.15 mM; [Organic compound]₀=0.1 mM; [PMS]₀=2 mM; [Phosphate... 52
Figure 18. Conversion of PMSO-to-PMSO₂ in manganese-based catalyst/persulfate system ([Mn(II)]₀=0.05 mM; [MnO₂]₀=0.4 g/L; [Mn-g-C₃N₄]₀=0.1 g/L; [Mn-N-... 54
Figure 19. Electrochemical impedance spectroscopic analysis of carbon paper electrodes coated with washed, unwashed Mn-N-C (various concentrations of Mn)... 56
Figure 20. Stability test of Mn-N-C in (a) PMS and (b) PDS activation processes. ([Mn-N-C]₀=0.05 g/L; [4-CP]₀=0.1 mM; [Persulfate]₀=2 mM; [Phosphate... 58
Figure 21. Stability test of MnO₂ in PMS activation processes. ([MnO₂]₀=0.4 g/L; [4-CP]=0.1 mM; [Persulfate]₀=2 mM; [Phosphate buffer]₀=1 mM; pHi=7.0).[이미지참조] 59
Figure 22. Adsorption of multiple organic compounds by Mn-N-C ([Mn-N-C]₀=0.05 g/L; [Organic compound]₀=0.1 mM; [Phosphate buffer]₀=1 mM; pHi=7.0).[이미지참조] 62
Figure 23. Formation of Cl⁻ by Mn-N-C/adsorption and persulfate systems ([Mn-N-C]₀=0.05 g/L; [4-CP]₀=[TCP]₀=0.1 mM; [Persulfate]₀=2 mM; [Phosphate... 63
Figure 24. Degradation of 4-CP by Mn-N-C (various concentrations of Mn) (a) Mn-N-C/adsorption ([Mn-N-C]₀=0.05 g/L; [4-CP]₀=0.1 mM; [phosphate buffer]₀=1... 65
Figure 25. Raman spectra of Mn-N-C (various concentrations of Mn). 66