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http://nopr.niscpr.res.in/handle/123456789/15761| Title: | Acid-base equilibrium of neutral red in benzene-in-water microemulsions |
| Authors: | Paul, B.C. Ismail, K. |
| Issue Date: | May-1999 |
| Publisher: | NISCAIR-CSIR, India |
| Abstract: | Acid-base equilibrium of neutral red (NR) has been studied spectrophotometrically at 25°C in two o/w microernulsions (ME's) containing benzene/sodium dodecyl sulphate/aqueous buffer/ 1-propanol (ME1) and benzene/sodium dodecyl sulphate/aqueous buffer/1-butanol (ME2). NR resides at the interfacial region of the MEs. A modified Henderson-Haselbach (HH) equation is found to be applicable and only one protonation of NR takes place in the pH range of 1.2 to 11 .2. NR appears completely in the protonated form at pH ≤ 4.5, and in the basic form at pH ≥ 9.5. The values of pKa, for NR in MEl and ME2 are found to be 6.88 and 7.05, respectively. These pKa values were factorized into contributions due to (1) effective dieiectric constant of the interfacial region, (2) interaction between protonated NR and negatively charged droplet, and (3) surface potential of the droplet. The surface potentials of the propanol and butanol containing droplets have been estimated to be approximately equal to -75 ± 10 and -85 ± 10 mV, respectively. |
| Page(s): | 496-500 |
| Appears in Collections: | IJC-A Vol.38A(05) [May 1999] |
Files in This Item:
| File | Description | Size | Format | |
|---|---|---|---|---|
| IJCA 38A(5) 496-500.pdf | 1.13 MB | Adobe PDF | View/Open |
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