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Analytical Methods for the Measurement of Chlorine Dioxide and Related Oxychlorine Species in Aqueous Solution

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Analytical Methods for the Measurement of Chlorine Dioxide and Related Oxychlorine Species in Aqueous Solution MIAMI UNIVERSITY The Graduate School Certificate for Approving the Dissertation We hereby approve the Dissertation of Zsolt Körtvélyesi Candidate for the Degree: Doctor of Philosophy Director Gilbert Gordon Chair Gilbert E. Pacey Reader James A. Cox Reader Michael W. Crowder Graduate School Representative John M. Hughes ABSTRACT ANALYTICAL METHODS FOR THE MEASUREMENT OF CHLORINE DIOXIDE AND RELATED OXYCHLORINE SPECIES IN AQUEOUS SOLUTION by Zsolt Körtvélyesi The main goal of this research was to seek a better understanding of the analytical measurements –– of the oxychlorine species ClO2, Cl24O , and Cl23O /Cl23O . The US EPA has developed a new colorimetric method for the measurement of ClO2 and chlorite ion (Method 327.0). This method is based on the decolorization of the dye Lissamine Green B (LGB) by ClO22. Chlorite ion is converted to ClO by Horseradish Peroxidase enzyme and measured with LGB. In the current work, the performance of this method (method detection limit, accuracy, and precision) was evaluated. The interference from dissolved chlorine, chloramine, iron(II), manganese(II), permanganate, and chlorate ions was studied. The underlying chemistry of these reactions is described and used to differentiate between interference and demand. A new method is suggested for the preparation of ClO2 standards by illuminating a mixture of chlorite ion and a photoacid. By using this method, ClO2 standards could be prepared reproducibly. Possible future developments for the method are also discussed. Chlorite ion interferes with the spectrophotometric measurement of ClO2 due to the formation of – the Cl24O complex. This complex has higher molar absorptivity than ClO2 at longer wavelengths where the absorbance of concentrated ClO2 solutions is measured. The formation constant of the complex is 5.0 M–1 as determined in this work. Based on this value, the molar absorptivity of the complex was calculated as a function of wavelength. These values were used to give recommen- dations to adjust the currently used spectrophotometric measurements. A new mixed disinfectant solution was developed and tested. This disinfectant is created from dissolved chlorine and ClO2. It is a potent disinfectant due to the formation of reactive intermediates resulting from the ClO2–chlorine reaction. A combination of chemical kinetic and microbiological results was used to estimate the efficacy of the new solutions. It was shown that in this way, fewer microbiological tests are required than using only microbiological results. This leads to shorter development time and lower costs. ANALYTICAL METHODS FOR THE MEASUREMENT OF CHLORINE DIOXIDE AND RELATED OXYCHLORINE SPECIES IN AQUEOUS SOLUTION A DISSERTATION Submitted to the Faculty of Miami University in partial fulfillment of the requirements for the degree of Doctor of Philosophy Department of Chemistry and Biochemistry by Zsolt Körtvélyesi Miami University Oxford, Ohio 2004 Dissertation Advisor: Dr. Gilbert Gordon © Zsolt Körtvélyesi 2004 T a b le o f co nte nts L is t o f t a b le s v iii List o f figures x List o f Ac r o nyms xv A c k n o w le d g me n t s x v ii 1. Int ro duct io n and Research Object ives 1 1 . 1 . T he c he mist r y o f c hlo r ine in a q u e o u s so lu t io ns 2 1.2. Chlo rine dio xide 3 1 . 2 . 1 . P h ys ic a l, c h e mic a l p r o p e r t ie s o f C lO 2 3 1.2.2. Properties of sodium chlorite 5 1 . 2 . 3 . G e n e r a t io n o f C lO 2 6 1 . 2 . 4 . Ap p lic a t io ns o f ClO2 in w a t e r t r e a t me nt 8 1.2.5. Safet y precaut io ns fo r r esearch labo rat o ries 10 1.3. Research o bject ives 10 2 . P r o p o se d E P A Me t ho d 3 2 7 . 0 : D e t e r mina t io n o f C lO 2 a nd C hlo r it e I o n in D r ink ing Wat e r U sing L is s a mine G r e e n B a n d H o r s e r a d is h P e r o xid a s e ( H R P ) w it h D e t e c t io n b y V is ible Spect ro pho t o met ry 12 2.1. Regulat io ns o f ClO2 in po t able wat er 13 2.2. Current ClO2 analyt ical met ho ds 13 2.2.1. Ideal Met ho d 14 2.2.2. Io do met ric met ho d 15 2.2.3. Spect ro pho t o met ric met ho d 16 2.2.4. Co lo rimet ric met ho ds 19 2.2.5. N, N’- d ie t h yl- p -phenylenediamine (DPD) met ho d 20 iii 2.2.6. Lissamine Green B (LGB) met ho d 23 2.2.7. Ot her co lo rimet ric met ho ds 24 2.2.8. Elect ro chemical met ho ds 25 2.3. Experiment al 26 2.3.1. Reagent wat er 26 2.3.2. Generat io n o f ClO2 26 2.3.3. Carbo nat e free so dium hydro xide so lut io ns 27 2.3.4. Preparat io n o f disso lved chlo rine so lut io ns 27 2.3.5. Preparat io n o f mo no chlo ramine 27 2.3.6. Tit rat io n o f chlo rine and mo no chlo ramine so lut io ns 28 2.3.7. Tit rat io n o f ClO2 and chlo rit e io n so lut io ns 28 2.3.8. Preparat io n and t it rat io n o f po t assium permanganat e so lut io ns 29 2.3.9. Ot her reagent s 29 2.3.10. Shrinking bo t t le 29 2.3.11. Ot her equipment 30 2.4. The pro po sed LGB met ho d 31 2.5. Result s o f t he second labo rat o ry experiment s 33 2.5.1. Met ho d det ect io n limit 37 2.5.2. Reco veries o f t he samples 38 2.6. Int erference st udies 41 2.6.1. Int erference in analyt ical measurement s 41 2.6.2. Demand vs. int erference 43 2.6.3. The int erferences st udied 45 2.6.4. Chlo rat e io n int erference 46 2.6.5. Ir o n(I I) int erference 48 2.6.6. Manganese(II) int erference 58 2.6.7. Manganese(VII ) int erference 61 2.6.8. Manganese(II) –Manganese(VII ) int erference 65 2.6.9. Free Available Chlo rine (FAC) int erference 71 iv 2.6.10. Mo no chlo ramine (NH2 Cl) int erference 73 2.6.11. Co nclusio ns o n t he int erference result s 74 2.7. Co nclusio ns 77 2.8. Fut ure direct io ns 78 2.8.1. Chlo rine dio xide st andards 78 2.8.2. Using gas diffusio n flo w inject io n analysis wit h pro po sed EPA Met ho d 327.0 80 – 3. The Cl24 O Co mplex 82 3.1. Theo ret ical 83 – 3.1.1. The hist o ry o f t he Cl24 O co mplex 83 3.2. Numerical met ho ds 85 3.2.1. Mat rix Rank Analysis 85 3.2.2. Det erminat io n o f fo rmat io n co nst ant s 89 3.2.3. PSE QUAD 91 3.2.4. Excel wo rkbo o k fo r t he det erminat io n o f fo rmat io n co nst ant s 93 3.3. Experiment al 94 3.3.1. Purificat io n o f so dium chlo rit e 94 3.3.2. Preparat io n o f so dium perchlo rat e so lut io n 95 3.3.3. Det erminat io n o f t he mo lar abso rpt ivit y o f ClO2 and chlo rit e io n 96 – 3.4. Pro blems wit h t he spect ro pho t o met ric measurement o f t he Cl24 O co mplex 98 3.5. Lo ng-perio d grat ing (LPG) senso r r esult s 98 3.5.1. The calibration of the LPG sensor for the determination of chlorite ion concentration 102 3.5.2. The calibration of the LPG sensor for the determination of ClO2 concentration 106 3.5.3. The respo nse o f t he LPG senso r in mixt ures o f ClO2 and chlo rit e io n 107 3.6. Init ial spect ro pho t o met ric result s 108 3.7. Main spect ro pho t o met ric st udy 112 3.7.1. The effect o f t emperat ure o n t he equilibrium 118 v 3.8. The st ruct ure o f t he complex 119 3.9. Met ho ds t o eliminat e t he int erference of t he complex 123 – 3.9.1.
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