@article { ISI:000258460400012, title = {Adsorption of sulfonated dyes by polyaniline emeraldine salt and its kinetics}, journal = {Journal of Physical Chemistry B}, volume = {112}, number = {33}, year = {2008}, month = {AUG}, pages = {10153-10157}, publisher = {AMER CHEMICAL SOC}, type = {Article}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

A method for the removal of anionic (sulfonated) dyes from aqueous dye solutions using the chemical interaction of dye molecules with polyaniline is reported. Polyaniline (PANI) emeraldine salt was synthesized by chemical oxidation. Sulfonated dyes undergo chemical interactions with the charged backbone of PANI, leading to significant adsorption of the dyes. This phenomenon of selective adsorption of the dyes by PANI is reported for the first time and promises a green method for removal of sulfonated organics from wastewater. The experimental observations from UV-vis spectroscopy, X-ray diffraction, and conductivity measurements rule out the possibility of secondary doping of polyaniline salt by sulfonated dye molecules. A possible mechanism for the chemical interaction between the polymer and the sulfortated dye molecules is proposed. The kinetic parameters for the adsorption of sulfonated dyes on PANI are also reported.

}, issn = {1520-6106}, doi = {10.1021/jp803903x}, author = {Mahanta, Debajyoti and Madras, Giridhar and Radhakrishnan, S. and Patil, Satish} } @article { ISI:000263529500010, title = {Adsorption and desorption kinetics of anionic dyes on doped polyaniline}, journal = {Journal of Physical Chemistry B}, volume = {113}, number = {8}, year = {2009}, month = {FEB}, pages = {2293-2299}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

In this study, we report an approach for the adsorption and desorption of anionic (sulfonated) dyes from aqueous solution by doped polyaniline. In this study, we have synthesized PANI with two dopants, namely, p-toluenesulfonic acid (PTSA) and camphorsulfonic acid (CSA), and used these to adsorb various dyes. It was found that the doped PANI selectively adsorbs anionic dyes and does not adsorb cationic dyes. The adsorption of anionic dyes causes the variation in electrical conductivity of PANI, indicating its potential as a conductometric sensor for these dyes at very low concentration. The adsorbed dyes were desorbed from the polymer by using a basic aqueous solution. The adsorption and desorption kinetics of the dye in the presence of doped PANI were also determined.

}, issn = {1520-6106}, doi = {10.1021/jp809796e}, author = {Mahanta, Debajyoti and Madras, Giridhar and Radhakrishnan, S. and Patil, Satish} } @article { ISI:000262810900014, title = {Conducting polyaniline-nano-TiO2 composites for smart corrosion resistant coatings}, journal = {Electrochimica Acta}, volume = {54}, number = {4}, year = {2009}, month = {JAN}, pages = {1249-1254}, publisher = {PERGAMON-ELSEVIER SCIENCE LTD}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND}, abstract = {

Coatings prepared from polyaniline-nano-TiO2 particles synthesized by in situ polymerization were found to exhibit excellent corrosion resistance much superior to polyaniline (PANI) in aggressive environments. The corrosion Studies were carried out on steel plates coated with these formulations containing 10 wt\% polyaniline prepared with different concentrations of nano-TiO2. The electrochemical impedance spectroscopy was studied at periodic intervals during exposure to hot saline (65 degrees C) conditions for prolonged durations over a period of 90 h. The open circuit potential (OCP) was found to shift with time from -0.38 V SCE to more anodic side (-0.2 V SCE) much above that of bare steel (-0.5 VSCE). The presence of nano-TiO2 was found to be vital in the prevention of corrosion and the shift of OCP to anodic side. From these data, one could envisage more than 100 times improvement in the corrosion resistance especially for polyaniline prepared with 4.18 wt\% nano-TiO2. The exceptional improvement of performance of these coatings has been associated with the increase in barrier to diffusion, prevention of charge transport by the nanosize TiO2, redox properties of polyaniline as well as very large surface area available for the liberation of dopant due to nano-size additive. (C) 2008 Elsevier Ltd. All rights reserved.

}, keywords = {Anticorrosion, Coating, conducting polymer, Nano-composite, Titanium dioxide}, issn = {0013-4686}, doi = {10.1016/j.electacta.2008.08.069}, author = {Radhakrishnan, S. and Siju, C. R. and Mahanta, Debajyoti and Patil, Satish and Madras, Giridhar} } @article { ISI:000291832800003, title = {Polyaniline modified electrodes for detection of dyes}, journal = {Synthetic Metals}, volume = {161}, number = {9-10}, year = {2011}, month = {MAY}, pages = {659-664}, publisher = {ELSEVIER SCIENCE SA}, address = {PO BOX 564, 1001 LAUSANNE, SWITZERLAND}, abstract = {

Polyaniline (PANI) is one of the most extensively used conjugated polymers in the design of electrochemical sensors. In this study, we report electrochemical dye detection based on PANI for the adsorption of both anionic and cationic dyes from solution. The inherent property of PANI to adsorb dyes has been explored for the development of electrochemical detection of dye in solution. The PANI film was grown on electrode via electrochemical polymerization. The as grown PANI film could easily adsorb the dye in the electrolyte solution and form an insulating layer on the PANI coated electrode. As a result, the current intensity of the PANI film was significantly altered. Furthermore, PANI coated stainless steel (SS) electrodes show a change in the current intensity of Fe(2+)/Fe(3+) redox peaks due to the addition of dye in electrolyte solution. PANI films coated on both Pt electrodes and non-expensive SS electrodes showed the concentration of dye adsorbed is directly proportional to the current intensity or potential shift and thus can be used for the quantitative detection of textile dyes at very low concentrations. (C) 2011 Elsevier B.V. All rights reserved.

}, keywords = {Electrochemical sensor, Emeraldine base, Emeraldine salt, polyaniline}, issn = {0379-6779}, doi = {10.1016/j.synthmet.2011.01.005}, author = {Mahanta, Debajyoti and Munichandraiah, N. and Radhakrishnan, S. and Madras, Giridhar and Patil, Satish} } @article { ISI:000288529500015, title = {Role of lattice defects and crystallite morphology in the UV and visible-light-induced photo-catalytic properties of combustion-prepared TiO2}, journal = {Materials Chemistry and Physics}, volume = {126}, number = {3}, year = {2011}, month = {APR}, pages = {546-554}, publisher = {ELSEVIER SCIENCE SA}, address = {PO BOX 564, 1001 LAUSANNE, SWITZERLAND}, abstract = {

The physico-chemical, photo-physical and micro-structural properties responsible for the strikingly different photocatalytic behavior of combustion-prepared TiO2 (c.TiO2) and Degussa P25 (d.TiO2) samples are elucidated in this study. Electron microscopy and selected area electron diffraction micrographs revealed that the two samples exhibited different morphologies. The grains of c.TiO2 were spherical and comprised of 5-6 nm size primary particle. On the other hand, d.TiO2 consisted of large (0.5-3.0 mu m) size and irregular shape aggregates having primary particles of 15-40 nm cross-sectional diameter. The ESR study revealed that the presence of certain defect states in c.TiO2 helped in stabilization of O-. and Ti3+-OH type species during room-temperature UV-irradiation. No such paramagnetic species were however formed over d.TiO2 under similar conditions. C1s and Ti 2p XPS spectra provide evidence for the presence of some lattice vacancies in c.TiO2 and also for the bulk Ti4+ -\> Ti3+ conversion during its UV-irradiation. Compared to d.TiO2, c.TiO2 displayed considerably higher activity for discoloration of methyl orange but very poor activity for splitting of water, both under UV and visible light radiations. This is attributed to enhanced surface adsorption of dye molecules over c.TiO2, because of its textural features and also the presence of photo-active ion-radicals. On the other hand, the poor activity of c.TiO2 for water splitting is related to certain defect-induced inter-band charge trapping states in the close vicinity of valence and conduction bands of c.TiO2, as revealed by thermoluminescence spectroscopy. Further, the dispersion of nanosize gold particles gave rise to augmented activity of both the catalysts, particularly for water splitting. This is explained by the promotional role of Au-0 or Au-0/TiO2 interfacial sites in the adsorption and charge-adsorbate interaction processes. (C) 2011 Elsevier B.V. All rights reserved.

}, keywords = {Band-structure, Interfaces, Microstructure, Nanostructures, Semiconductors}, issn = {0254-0584}, doi = {10.1016/j.matchemphys.2011.01.029}, author = {Deshpande, Aparna and Madras, Giridhar and Gupta, N. M.} } @article {49233, title = {Efficient glycolysis of used PET bottles into a high-quality valuable monomer using a shape-engineered MnO nanocatalyst}, journal = {CATALYSIS SCIENCE \& TECHNOLOGY}, volume = {14}, year = {2024}, month = {SEP }, type = {Journal Article}, keywords = {Catalyst, kinetics, Nanorods, Oxidation, Oxides, POLY(ETHYLENE-TEREPHTHALATE), WASTE}, issn = {2044-4753}, doi = {10.1039/d4cy00823e}, author = {Swapna, Bhattu and Singh, Nittan and Patowary, Suranjana and Bharali, Pankaj and Madras, Giridhar and Sudarsanam, Putla} }