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Removal of Cadmium from Aqueous Solution Using Castor Seed Hull: A Kinetic and Equilibrium Study
Author(s) -
Sen Tushar Kanti,
Mohammod Masita,
Maitra Saikat,
Dutta Binay K.
Publication year - 2010
Publication title -
clean – soil, air, water
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.444
H-Index - 66
eISSN - 1863-0669
pISSN - 1863-0650
DOI - 10.1002/clen.200900246
Subject(s) - adsorption , langmuir , cadmium , freundlich equation , chemistry , activated carbon , aqueous solution , metal ions in aqueous solution , langmuir adsorption model , monolayer , metal , inorganic chemistry , organic chemistry , biochemistry
The effects of various parameters such as initial concentration, adsorbent loading, pH, and contact time on kinetics and equilibrium of adsorption of Cd 2+ metal ion from its aqueous solution by castor seed hull (CSH) and also by activated carbon have been investigated by batch adsorption experiments. The amount of adsorption increases with initial metal ion concentration, contact time, solution pH, and the loading of adsorbent for both the systems. Kinetic experiments indicate that adsorption of cadmium metal ion on both CSH and on activated carbon consists of three steps – a rapid adsorption of cadmium metal ion, a transition phase, and an almost flat plateau region. This has also been confirmed by the intraparticle diffusion model. The lumped kinetic results show that the cadmium adsorption process follows a pseudo‐second order rate law. The kinetic parameters including the rate constant are determined at different initial metal ion concentrations, pH, amount, and type of adsorbent, respectively. The Langmuir and Freundlich adsorption isotherm models are used to describe the experimental data. The Langmuir model yields a better correlation coefficient than the other model. A comparison of the monolayer adsorption capacity ( q m ) of CSH, activated carbon, and several other reported adsorbents has been provided. The value of separation factor ( R L ) calculated from the Langmuir equation also gives an indication of favorable adsorption of the metal ion. From comparative studies, it has been found that CSH is a potentially attractive adsorbent than commercial activated carbon for cadmium metal ion (Cd 2+ ) removal.