THE ELECTROLYTIC PRODUCTION OF PEROXYDISULFURIC ACID It USING PERIODICALLY REVERSED DIRECT CURRENT AND ALTERNATING CURRENT SUPERIMPOSED ON DIRECT CURRENT by Sin-Chou Fan Thesis submitted to the Graduate Faculty of the Virginia Polytechnic Institute in candidacy for the degree of MASTER OF SCIENCE in CHEMICAL ENGINEERING APPROVED: APPROVED: ~rector of Graduate Studies Head of Department ~ean of'"Engineering Major· Professor v July, 1956 Blacksburg, Virginia -ii- TABLE OF CONTENTS Page I. INTRODUCTION • • • . • • • • . • • • 1 II. LITERATURE REVIEW . 3 Properties and Uses of Peroxydisulfuric Acid . 3 Methods of Preparing Peroxydisulfuric Acid • . 5 Chemical Methods of Preparing Peroxy- disulfuric Acid . 5 Electrolytic Methods of Preparing Peroxy- disulfuri c Acid • • • • • • • 6 Electrolysis with Periodically- Reversed Direct Current • • • • . 11 Definitions • • • • • • 11 Periodic Reverse Wave Forms • • 13 Use of Complex Wave Forms . 16 Periodic Reverse Electro- chemical Reaction • • • . 16 Limitations of Periodic Reverse Electrolysis • . 18 Current Reversal Equipment • 19 Electrolysis with Alteniating Current Superimposed on Direct Current • • • • • • • . 20 Electric Double Layer . 20 -iii- Page Polarizable Electrode • • • • • 21 Types of Superimposed Alternating Current • • • • • 23 Depolarization by Alter- nat~ng Current • • • • • • • • 26 Experimental Work on Alternating Current Depolarization • • • . 34 Electrolysis of Sulfuric Acid with Alternating Current Superimposed on Direct Current • • • • • • 40 Applications • • • • • • 43 Electrolytic Production of Lead Chromate Using Alternating Current Superimposed on Direct Current • • • • • • 44 Other Applications • • • • . 46 Advantages of Alternating Current Superimposed on Direct Current • • • • • . 47 Comparison of Superimposed Alternating Current Plating with Periodic Reverse Current Plating . Electric Circuits for Superimposing Alternating Current • • • • • • • • . 50 III. EXPERIMENTAL • • • • . • • • . 57 Purpose of Investigation • • • • • • 57 -iv- Page Plan of Investigation • • . 57 Literature Search . 57 General Procedure . 58 Evaluation of Results . 59 Materials • • • • . 60 Apparatus • • . • • • • • . 62 Method of Procedure • • • • . 67 Operating Procedure for Direct Current Electrolyses • • • • • . 67 Operating Procedure for Periodically-Reversed Direct Current Tests • . 71 Operating Procedure for Electrolyses Performed with Alternating Current Superimposed on Direct Current • • • • • • • • • • • 73 Relationship Between Root- Mean-Square and Peak Values of High Frequency Alternating Current ••• . 76 Operating Procedure for Measuring Anode Potential- Current in Sulfuric Acid • . 76 Operating Procedure for Measuring the Anode Potential-Current in Sulfuric Acid with Super- imposed Alternating Current • • • • • • • • • • • 78 Analytical Procedure • . 78 -v- Page Data and Results . 80 Calibration Data for the Periodic Reverser • • . 80 Periodic Reverser Calibra- tion Curves • • • • • • • • • 80 Operating Conditions, Data and Results for the Elec- trolytic Production of Peroxydisulfuric Acid Using Direct Current • • • . 80 Operating Conditions, Data and Results for the Elec- trolytic Production of Peroxydisulfuric Acid Using Periodically Reversed, Direct Current • • • • • • • • 80 Operating Conditions, Data and Results for Electro- lytic Production of Peroxy- disulfuric Acid Using Alternating Current, 60 Cycles per Second, Super- imposed on Direct Current • • 84 Operating Conditions, Data and Results for the Elec- trolytic Production of Peroxydisulfuric Acid Using Alternating Current, 240 and 500 Cycles per Second, Superimposed on Direct Current • • • • • • • • • • • 84 Data from the Measurements of Current-Anode Potential Curve in Sulfuric Acid with Stirring • • • • • • • • • • • 84 -vi- Page Data from the Measurements of Current-Anode Poten- tial Curve in Sulfuric Acid without Stirring • • • • 89 Data from the Measurements of Current-Anode Poten- tial Curve in Sulfuric Acid by Using 60 Cycles per Second, Superimposed Alternating Current • • • • • 89 Sample Calculations ••• . 92 Volume of Anolyte . 92 Anode Current Density • • • 94 Peroxydisulfuric Acid Produced • • • • . 95 Actual Current • • • • . 96 Current Efficiency • . 97 Direct to Reverse Current Ratio from Coulometers • • • • 98 Ratio of Peak Alternating Current to Direct Current . 100 IV. DISCUSSION • . 101 General Discussion . 101 Previous Work . 101 Selection of Anolyte Concentration • • . • • 102 Influence of Temperature on the Formation of Peroxy- disulfuric Acid • • • • • 103 -vii- Page Treatment of Platinum Anode • • • • • • . 104 Influence of Current Density • • • • • • • • • • • 105 Formation and Decomposition of Peroxydisulfuric Acid • • • 106 Decomposition Potential of Sulfuric Acid of Specific Gravity 1.4 •• . 107 Discussion of Results from Direct Current Electrolyses • • 113 Hydrogen and Oxygen Bubbles • • 113 Effect of Current Density • • • 113 Relationship Between the Time of Electrolysis and Current Efficiency . 118 Discussion of Results for Periodically-Reversed, Direct Current Electrolysis • • • • 121 Production of Peroxydisul- furic Acid Using Period- ically-Reversed, Direct Current • • • • • • • • • • • 121 Depolarization Action of Periodically-Reversed, Direct Current • • • • . • • 123 Ammeter Fluctuations During Current Reversal • • • ~ • • • 125 Time and Current Ratio • . 128 Comparison of Current Efficiencies • • • • • • • • • 129 -viii- Page Discussion of Results from Alternating Current Super- imposed on Direct Current Electrolyses • • • • • • • • • • • 131 Formation of Peroxydisul- fµric Acid with 60-Cycle, Alternating Current Super- imposed on Direct Current • • 131 Formation of Peroxydisul- furic Acid with 500-Cycle, Superimposed Alternating Current • • • • • • • • • • • 135 Formation of Pero:x:ydisul- furic Acid with 240-Cycle Alternating Current Super- imposed on Direct Current • • 136 Summary of Effect of Frequency • • • • • • • • • • 136 Behavior of Platinum Electrode • • • • • . Current Efficiency • • • • • . Comparison of Current Efficiencies • • • • . • • • 139 Recommendations • • • • • • . 142 Limitations • • • • • • . 145 v. CONCLUSIONS - • • • • • • • • • • . 148 VI. SUMMARY • • • • • • • • • • • • • • • • • 151 VII. BIBLIOGRAPHY • • • . • • • • • . 155 VIII. ACKNOWIEDGMENTS . 162 IX. VITA • • • • • • . • • 163 -ix- LIST OF TABLES Page TABLE I. Calibration Data for Plater's Research Corporation ' Periodic Reverser . • . • • 81 TABLE II. Operating Conditions, Data and Results Obtained from the Electrolytic Production of Peroxydisulfuric Acid . • • . • • 83 TABLE III. Operating Conditions, Data and Results Obtained from the Electrolytic Production of Peroxydisulfuric Acid Using Periodically-Reversed, Direct Current . • • • • . • 85 TABLE IV. Operating Conditions, Data and Results Obtained from the Electrolytic Production of Peroxydisulfuric Acid Using Alternating Current, 60 Cycles, Superimposed on Direct Current . • . • • • . • 86 TABLE v. Operating Conditions, Data and Results Obtained from the Electrolytic Production of Peroxydisulfuric Acid Using High Frequency of Alternating Current Superimposed on Direct Current . • • • • . • . 87 TABLE VI. Data from the Measurements of Current-Anode Potential Curve in Sulfuric Acid with Stirring • • . • • • • . • • 88 TABLE VII. Data from the Measurements of Current-Anode Potential Curve in Sulfuric Acid without Stirring • • • • • • . • 90 -x- Page TABLE VIII. Data from the Measurements of Current-Anode Potential Curve in Sulfuric Acid Using Superimposed alternating Current • • • • • • • • • • • • • 91 -xi- LIST OF FIGURES Page Figure 1. Time-Current Curves for Various Wave Forms . • • • . • 17 Figure 2. Representation of the Poten- tial-Distance Relation for the Electrode-Solution Interface . • • • . • • • • . • 22 Figure 3. Time-Current Relations for Alternating Current Superimposed on Direct Current • • . • . • • • • . 24 Figure 4. Experimental Hook-Up Used to Study the Effect of Super- imposed Alternating Current on Direct Current on the Electrodeposition of Aluminum . • • . • . • • • • . • . 52 Figure 5. Experimental Hook-Up Used to Study the Effect of Super- imposed Alternating Current on Direct Current on the Anodic Behavior of A-A Type Nickel . • . • . • 53 Figure 6. Experimental Hook-Up Used to Study the Effect of Super- imposed Alternating Current on Direct Current on the Anodic Behavior of Nickel . • • 55 Figure 7. Experimental Hook-Up Used to Study the Effect of Super- imposed Alternating Current on Direct Current on the Electrodeposition of Copper- Lead Alloys from Fluoborate Solutions • • • . • • . • 56 -xii- Page Figure 8. Wiring Diagram of Equipment Used to Study the Electro- lytic Production of Peroxy- disulfuric Acid Using Direct Current • • • • • • • . 69 Figure 9. Wiring Diagram of Equipment Used to Study the Electro- lytic Production of Peroxy- disulfuric Acid Using Periodically Reversed Direct Current • • • • • • . 72 Figure 10. Experimental Circuit Used to Study the Effect of Super- imposed Alternating Current on the Production of Peroxy- disulfuri c Acid • • • • • • • • • 74 Figure 11. Experimental Circuit Used for Measuring Current-Anode Potential Curve • • • • • • . 77 Figure 12. Graph Showing the Relationship Between the Ratio of Direct to Reverse Time and the Dial Settings for the Periodic Reverser • • • • • • • • • • . 82 Figure 13. Relationship Between Current and Anode Potential in Sulfuric Acid with Stirring . 108 Figure 14. Relationship Between Current and Anode Potential in Sulfuric Acid without