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Chakravarty P.,Birjhora Mahavidyalaya | Sarma N.S.,Polymer Section | Sarma H.P.,Gauhati University
Desalination | Year: 2010

Removal of lead(II) from aqueous solution was studied using the powder of heartwood of Areca catechu as a new biosorbent under batch method at room temperature. Various sorption parameters such as contact time, initial concentration of lead(II) ion, effect of pH and amount of the biomass on the adsorption capacity of the biosorbent were studied. The adsorbent was effective for the quantitative removal of lead(II) ions in acidic conditions and equilibrium has been achieved in 25. min. The equilibrium adsorption data were fitted to Langmuir and Freundlich adsorption isotherm models and the model parameters were evaluated. The kinetic study showed that the pseudo-second order rate equation better described the biosorption process. The FT-IR spectra of the adsorbent before and after treatment with lead(II) solution indicated that hydroxyl, carboxyl, amide and amine groups were major binding sites with the metal. This method is quite feasible, economic, time saving, and low cost. © 2010 Elsevier B.V. Source


Chakravarty P.,Birjhora Mahavidyalaya | Sarma N.S.,Polymer Section | Sarma H.P.,Gauhati University
Chemical Engineering Journal | Year: 2010

The ability of abundantly available heartwood of Areca catechu to adsorb cadmium(II) ions from aqueous solution has been investigated through batch experiments at room temperature. Various sorption parameters such as contact time, initial concentration of cadmium(II) ion, solution pH and amount of the biomass on the adsorption capacity, were studied. The adsorbent was found to be effective for quantitative removal of cadmium(II) ions in acidic conditions and equilibrium has been achieved in 30. min at pH 6.0. The equilibrium adsorption data were fitted to Langmuir, Freundlich and Dubinin-Radushkevich adsorption isotherm models and the model parameters were evaluated. The kinetic study showed that the pseudo-second-order rate equation better described the biosorption process. The FT-IR spectrum analysis revealed that hydroxyl, carboxyl, amide and amine groups were major cadmium(II) binding groups. © 2010 Elsevier B.V. Source


Dutta P.,Polymer Section | Saikia P.,Polymer Section | Hoque S.,Gauhati University | Nath Dass N.,Polymer Section | Sarma N.S.,Polymer Section
Molecular Crystals and Liquid Crystals | Year: 2015

Novel liquid crystalline polyesters of cholesterol, Polycholesteryl-3,3-dimethylacrylate (PCHDMA) and Polycholesterylcrotonate (PCHC) are synthesized by free radical polymerization and characterized by FT-IR, 1H-NMR, and GPC analysis. The thermal properties are studied by TGA and DSC techniques. The liquid crystalline phases are detected under hot stage optical microscope. Electronic conduction in the polymers is determined by Wagner polarization technique. There is about 5000 fold decrease in the impedance values of both PCHDMA and PCHC on increasing the frequencies from 40 Hz to 1 MHz at 30°C. Amperometric analysis of the polymers are also carried out at different temperatures and frequencies. Copyright © Taylor & Francis Group, LLC 2015. Source


Chakravarty P.,Birjhora Mahavidyalaya | Deka D.C.,Birjhora Mahavidyalaya | Sarma N.S.,Polymer Section | Sarma H.P.,Gauhati University
Desalination and Water Treatment | Year: 2012

The adsorptive behavior of heartwood powder of Areca catechu for copper(II) ion from synthetic wastewater has been investigated as a function of contact time, initial concentration of copper(II) ion, solution pH and biosorbent dosage, using batch method at room temperature. The optimum conditions for the metal adsorption were found to be at 0.5 g biosorbent dose, pH 5.5, and 30 min equilibrium time for the entire concentration range of the adsorbate. The equilibrium adsorption data were fitted to Langmuir, Freundlich and Dubinin-Radushkevich adsorption isotherm models and the model parameters were evaluated. The maximum adsorption capacity obtained from Langmuir isotherm model was found to be 9.578 mg g-1. The kinetic study showed that the pseudo-second-order kinetic model better described the biosorption process in comparison to pseudo-first-order, Elovich and intraparticle diffusion kinetic model. FT-IR spectrum analysis revealed that O-H, N-H and C-O groups present in the adsorbent were the primary copper(II) ion binding groups. © 2012 Desalination Publications. All rights reserved. Source


Hoque S.,Polymer Section | Dass N.N.,Polymer Section | Bhattacharyya K.G.,Gauhati University | Sarma N.S.,Polymer Section
Polymer - Plastics Technology and Engineering | Year: 2013

The synthesis of polycholesterylmethacrylate and poly(cholesterylmethacrylate-co-1-hexene) at different monomer feed ratios with their liquid crystalline behaviours have been reported in this article. Liquid crystalline phases of the polymer and copolymers have been detected under the hot stage microscope and also by differential scanning calorimetric and X-ray diffraction technique. The polymers are characterized by IR spectroscopy, proton NMR spectroscopy and GPC system. The reactivity ratios of cholesterylmethacrylate and 1-hexene are found to be r1 = 2 and r2 = 1.6, respectively. The number average molecular weight of the polymer is 1.01 × 104 Daltons and that of the copolymers are much higher than the polymer. © 2013 Copyright Taylor and Francis Group, LLC. Source

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