Sorokhaibam Laxmi Gayatri - Batch adsorption of 4-nitrophenol by acid activated jute stick char: Equilibrium, kinetic and thermodynamic studies

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      Ahmaruzzaman, M., Laxmi Gayatri, S. Chemical Engineering   Journal 2010 -

      Abstract: The article describes the performance   of acid activated jute stick char (AAJSC) for the adsorption of   4-nitrophenol (4-NP) from aqueous solution in batch mode. Jute   stick, a bulk volume agricultural waste, was utilized for   adsorption. The char of jute stick prepared at 773 K was   activated with phosphoric acid and adsorption experiments were   carried out at 298, 308 and 318 K. Equilibrium adsorption data   were analyzed using two-parameter models-Langmuir, Freundlich,   Temkin, Dubunin-Radushkevich and three-parameter-Redlich-Peterson   model. The goodness of the fit was measured using linear   regression coefficient (R2) value and five different error   functions. The adsorption data was found to be well described by   Langmuir model. The equilibrium time for adsorption was achieved   within 4 h. Studies showed that adsorption decreases with the   increasing temperature. pH studies were also performed to obtain   the equilibrium pH for adsorption. The pseudo-first-order,   pseudo-second-order and Elovich kinetic models were applied to   test the kinetic data, and were found to closely follow the   pseudo-second-order kinetic model. The thermodynamic constants of   the adsorption process; ??G??, ??H?? and ??S?? were evaluated as   -18.79 kJ/mol at 25 ??C, 3917.4 J/mol, 76.21 J/mol K-1   respectively. These showed that the adsorption process was   endothermic and spontaneous. ?? 2009 Elsevier B.V. All rights   reserved.

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