Heat Activated Persulfate Oxidation of Dye Solutions

ABSTRACT

This study investigates the decolourization of reactive blue 4 textile dye solution by heat activated persulfate. Synthetic textile dyes have been found to be non-biodegradable, toxic and carcinogenic and thus potentially harmful to both the environment and living organisms when improperly discharged to the environment. A lot of attention have been given to Azo dyes which make up approximately 60% of the reactive dyes with limited study conducted on other classes of reactive dyes such as anthraquinone dyes which are extensively used in the textile industry to colour cotton as well as polyamide fibres. The use of persulfate for advanced oxidation processes is on the increase and heat activated persulfate advanced oxidation is an attractive technology for wastewater treatment. Three different temperatures 40oC, 50oC, and 60oC and dye/persulfate ratios 1/10, 1/20, 1/40, 1/80, 1/100, 1/500 were studied with dye concentration at 0.157Mm. The changes in pH values after 60mins of reaction time were observed and spectroscopic studies were used to determine the change in dye concentrations. The results showed that increasing the temperature and persulfate concentration was favourable to the degradation of the dye with decolourization efficiency as high as 99% observed at dye/persulfate ratio of 1/500 and temperature of  600C after 30mins of reaction.

TABLE OF CONTENT

ABSTRACTi

ACKNOWLEDGEMENTii

TABLE OF CONTENTiii

LIST OF FIGURESv

LIST OF TABLESvii

LIST OF ABBREVIATIONSviii

CHAPTER ONE1

INTRODUCTION1

CHAPTER TWO4

LITERATURE REVIEW4

2.1 Reactive Dyes4

     2.1.1 Reactive blue 44

2.2 Dye toxicity evaluation5

2.3 Biological treatment of textile dye effluents6

2.4 Advanced Oxidation Processes (AOPs)7

     2.4.1 Wet Air Oxidation7

     2.4.2 Photocatalytic treatment8

     2.4.3 Fenton treatment8

         2.4.3.1 Electro-Fenton treatment9

      2.4.4 Ozonation9

     2.4.5 Use of Activated Carbon10

     2.4.6 Persulfate Advanced Oxidation Process10

2.5 Properties of Persulfates11

2.6 Mechanism of persulfate degradation of organic compounds11

2.7 Persulfate Activation Methods12

     2.7.1 Base activation12

     2.7.2 Transition metal Activation12

     2.7.3 Radiation Activation13

     2.7.4 Hybrid Activation13

     2.7.5 Heat activation14

2.8 Effect of Natural water constituents on Heat-activated Persulfate Processes.15

     2.8.1 Chlorides, Bicarbonates and Natural Organic Matter15

CHAPTER THREE17

MATERIALS AND METHODS17

3.1 Chemicals and Apparatus17

3.2 Experimental Methodology17

3.3 Analytical Procedure18

3.4 Kinetics of RB4 degradation process18

CHAPTER FOUR19

RESULTS AND DISCUSSION19

4.1 Effect of Persulfate dosage19

4.2 Effect of Temperature25

4.3 KINETIC STUDY27

4.4 CHANGE IN pH29

CHAPTER FIVE30

CONCLUSION30

REFERENCES31

APPENDIX36

 LIST OF FIGURES

Figure 2.1 Structure of reactive blue 45

Figure 2.2 Structure of sodium persulfate11

Figure 4.1 Change in RB4 dye concentration with time at 400C and different PS concentrations20

Figure 4.2 Change in RB4 dye concentration with time at 500C and different PS concentrations20

Figure 4 3 Change in RB4 dye concentration with time at 600C and different PS concentrations21

Figure 4.4 Standard deviation error bars at 400C and 1/10 (dye/PS)21

Figure 4.5. Standard deviation error bars at 400C and 1/20 (dye/PS)22

Figure 4.6. Standard deviation error bars at 400C and 1/40 (dye/PS)22

Figure 4.7. Standard deviation error bars at 400C and 1/80 (dye/PS)23

Figure 4.8. Standard deviation error bars at 400C and 1/100 (dye/PS)23

Figure 4.9. Standard deviation error bars at 400C and 1/500 (dye/PS)24

Figure 4.10. Standard deviation error bars at 500C and 1/10 (dye/PS)24

Figure 4.11. Standard deviation error bars at 500C and 1/20 (dye/PS)25

Figure 4.12 Change in RB4 dye concentration with time at 1:10 (dye/PS) and different temperatures.26

Figure 4.13 Change in RB4 dye concentration with time at 1:100 (dye/PS) and different temperatures.26

Figure 4.14 Kinetic study of RB4 degradation process at 400C and different dye/PS ratios27

Figure 4.15 Kinetic study of RB4 degradation process at 500C and different dye/PS ratios28

Figure 4.16 Kinetic study of RB4 degradation process at 600C and different dye/PS ratios28

Figure A.1 Calibration curve for dye at 598nm36

Figure A.2 Rate constants vs PS concentrations36

LIST OF TABLES

Table 2.1 Properties of Persulfate11

Table 4.1 Initial and final pH values29

Table 4.2 K values (min-1)29

Table A.1 Estimated K values (500C)37

Table A.2 Estimated K values (600C)37

Table A.3 Data for 1.57mM PS at 400C and 0.157mM RB437

Table A.4 Data for 3.14mM PS at 400C and 0.157mM RB438

Table A.5 Data for 6.28mM PS at 400C and 0.157mM RB438

Table A.6 Data for 12.56mM PS at 400C and 0.157mM RB439

Table A.7 Data for 15.7mM PS at 400C and 0.157mM RB439

Table A.8 Data for 78.5mM PS at 400C and 0.157mM RB440

Table A.9 Data for 1.57mM PS at 500C and 0.157mM RB440

Table A.10 Data for 3.14mM PS at 500C and 0.157mM RB441

Table A.11 Data for 12.56mM PS at 500C and 0.157mM RB441

Table A.12 Data for 15.7mM PS at 500C and 0.157mM RB442

Table A.13 Data for 1.57mM PS at 600C and 0.157mM RB442

Table A.14 Data for 15.7mM PS at 600C and 0.157mM RB443

Table A.15 Data for 78.5mM PS at 600C and 0.157mM RB443