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Dutta, Robin K.
- A Partition Equilibrium Study of Sulfonephthalein Dyes in Nonionic Surfactant Systems at High pH
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Authors
Affiliations
1 Department of Chemistry, Darrang College, Tezpur 784 001, Assam, IN
2 Department of Chemical Sciences, Tezpur University, Napaam, Tezpur 784 028, Assam, IN
1 Department of Chemistry, Darrang College, Tezpur 784 001, Assam, IN
2 Department of Chemical Sciences, Tezpur University, Napaam, Tezpur 784 028, Assam, IN
Source
Journal of Surface Science and Technology, Vol 23, No 3-4 (2007), Pagination: 195-208Abstract
The acid base equilibria of two sulfonephthalein dyes, viz., bromothymol blue (BTB) and bromocresol green (BCG) in aqueous nonionic micellar solutions of Triton X100, Tween 20, Tween 40, Tween 60 and Tween 80 have been investigated spectroscopically using a partition equilibrium method. A red shift in the λmax of the visible absorption band corresponding to the base forms of the dyes with increase in surfactant concentration was observed at and above pH 9.0. For a particular dye-surfactant system the red shift increases with the increase in pH and was found to be greater for TX 100 than for the Tween surfactants. Red shift of the λmax of BTB was observed to be greater than that of BCG in all of the nonionic micellar systems investigated in buffered medium. The observed red shift has been attributed to stabilization of the base form of the dye by the polyoxyethylene (POE) head groups. The stabilization effect was found to decrease with increase in the number of carbon atom and unsaturation in the hydrophobic tail of the surfactant molecules. The equilibrium constant of the partition of the dyes between micellar and aqueous pseudophases (Kass) was found to be greater for the more hydrophobic BTB than the less hydrophobic BCG. With the surfactants the Kass increases in the order Tween 80 < Tween 60 < Tween 40 < Tween 20 < TX 100. The pKa2 of the dyes were predicted using a partition equilibrium model and found to be in good agreement with the experimental values.Keywords
Sulfonephthalein Dyes, Partition Equilibrium, Nonionic Surfactant, Micelle and Acid-Base Equilibrium.- Mahi:A Unique Traditional Herbal Ink of Early Assam
Abstract Views :411 |
PDF Views:108
Authors
Barsha R. Goswami
1,
Monoj K. Das
2,
Pranjal P. Das
2,
Tapas Medhi
2,
Anand Ramteke
2,
Simanta Hazarika
3,
Robin K. Dutta
1
Affiliations
1 Department of Chemical Sciences, Tezpur University, Tezpur-784 028, IN
2 Department of Molecular Biology and Biotechnology, Tezpur University, Tezpur-784 028, IN
3 Department of Physics, Gauhati University, Guwahati 781 014, IN
1 Department of Chemical Sciences, Tezpur University, Tezpur-784 028, IN
2 Department of Molecular Biology and Biotechnology, Tezpur University, Tezpur-784 028, IN
3 Department of Physics, Gauhati University, Guwahati 781 014, IN
Source
Current Science, Vol 112, No 03 (2017), Pagination: 591-595Abstract
Mahi, a unique herbal ink prepared with cow urine as extractant, was used for manuscript writing in early Assam. The ink had a deep and fast colour and was persistent on Sancipat manuscripts due to its re-sistance to aerial oxidation and fungi. It was also non-corrosive unlike the corrosive acidic iron gall ink of contemporary Europe. The present study was aimed at analysing the physico-chemical properties of Mahi, including its special properties. The study includes phytochemical analysis, antimicrobial assay, UV-visible with fluorescence analysis, iron and copper estimation and identification of some polyphenols by HPLC-UV.Keywords
Ancient Manuscripts, Physico-Chemical Properties, Spectroscopic Analysis, Traditional Herbal Ink.- Field Experience of Fluoride Nilogon:A Method of Fluoride Removal from Groundwater
Abstract Views :440 |
PDF Views:118
Authors
Rajkamal Mohan
1,
Sweety Gogoi
1,
Anup J. Bora
1,
Gautam Baruah
1,
Shreemoyee Bordoloi
1,
Asadulla A. Ali
1,
Hridip R. Sarma
1,
Robin K. Dutta
1
Affiliations
1 Department of Chemical Sciences, Tezpur University, Napaam 784 028, IN
1 Department of Chemical Sciences, Tezpur University, Napaam 784 028, IN
Source
Current Science, Vol 118, No 2 (2020), Pagination: 255-263Abstract
Field trial of a patented fluoride removal method, based on precipitation–adsorption, has been carried out in some villages of Assam, North East India, with groundwater sources containing 1.8–20 mg/l initial [F–] at small community (220 l) and household (15 l) levels. Pre-acidified water containing 0.68 mM phos-phoric acid was treated in a crushed limestone bed (1–20 mm) for 3 h and filtered through a sand–gravel filter to retain a desired 0.7 mg/l [F–] with pH of 7.44–7.9 and relevant water quality parameters meeting WHO guidelines. A slightly higher dose can totally remove fluoride. The fluoride removal has been found to be independent of initial [F–]. The units have been showing consistent results till now for over five and half years and 4625 batches of use without requiring any interventions like reactivation, replacement or re-plenishment of the limestone bed. With consistent re-moval of fluoride from any initial concentration to a desired concentration, a recurring cost of only Rs 0.005/l of water and an estimated life of the lime-stone bed of about 50 years or 39,000 batches, this safe, environment-friendly and simple method without requiring electricity, has been gaining popularity as Fluoride Nilogon.Keywords
Fluoride Removal, Groundwater, Hydroxy-apatite, Limestone Defluoridation, Phosphoric Acid.References
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- Sāncipāt: a popular manuscript writing base of early Assam, North East India
Abstract Views :274 |
PDF Views:132
Authors
Affiliations
1 Department of Chemical Sciences, Tezpur University, Tezpur 784 028, India, IN
1 Department of Chemical Sciences, Tezpur University, Tezpur 784 028, India, IN
Source
Current Science, Vol 123, No 11 (2022), Pagination: 1359-1364Abstract
Sāncipāt was a popular manuscript writing base of early and medieval Assam, North East India. Tens of thousands of Sāncipāt manuscripts still exist in the state, some of them centuries old, without fading ink and miniature painting despite its harsh hot and humid climate. Traditionally, Sāncipāt was made from the bark of the Sānci tree using an arduous procedure. In this study, we analysed the physico-chemical properties of the traditionally prepared model and old Sāncipāt folios at different stages of preparation using FT-IR, XRD and SEM-EDX spectra, weight loss during degumming, tensile strength, gloss index and antifungal properties. A comparison of data with freshly prepared Sāncipāt folios showed intact internal structure and strength in the old ones. The antifungal property observed in Sāncipāt is attributed to Tutia used during degumming of the bark, and two pigments, viz., Hengul and Hāitāl applied as thin coating and border respectively. Partial degumming, coating with fatty pulse, application of Hāitāl and Hengul, and repeated pressing, smoothening and drying together impart strength and glossiness to Sāncipāt manuscripts.Keywords
Antifungal activity, degumming, gloss index, medieval writing base, Sāncipāt manuscripts.References
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