title: Thermodynamics of cadmium sorption on different soils of West Bengal, India.
abstract: A sorption study was conducted on different soils collected from five agroecological zones of West Bengal, India, to understand the soil environmental behavior and fate of cadmium. For this purpose batch adsorption experiments were carried out at the native soil pH and at three different temperatures (25°C, 35°C, and 45°C). The adsorption data fitted by a linear least squares technique to the different sorption isotherms. Most data obtained give the good fit to both Freundlich and modified Langmuir isotherms, but they are not consistent with the linear Langmuir adsorption model. Thermodynamic parameters, namely, thermodynamics equilibrium constant at a particular temperature T (K T (0)), Gibbs free energy at a particular temperature T (ΔG T (0)), and change of enthalpy (ΔH (0)) and change of entropy at temperature T (ΔS T (0)), were also determined by applying sorption value and concentrations of Cd in equilibrium solution within the temperature range. The thermodynamic parameters revealed that Cd sorption increases as the values of K T (0), ΔG T (0), ΔH (0), and ΔS T (0) were increased on reaction temperatures. The spontaneous sorption reaction can be concluded due to high values of ΔG T (0). The positive values of ΔH (0) indicated that the Cd sorption is an endothermic one. Under these present conditions, the soil and its components possibly supply a number of sites having different adsorption energies for cadmium sorption.
authors.affiliation: Department of Agricultural Chemistry and Soil Science, Faculty of Agriculture, Bidhan Chandra Krishi Viswavidyalaya, Mohanpur, Nadia, West Bengal 741252, India ; Upper Assam Advisory Centre, Tea Research Association, Dikom, Assam 786101, India.
authors.forename: Tanmoy
authors.identifier: 0000-0003-4179-2529
authors.initials: T
authors.lastname: Karak
authors.affiliation: Division of Statistical Genetics, Indian Agricultural Statistics Research Institute, New Delhi 110012, India.
authors.forename: Ranjit Kumar
authors.initials: RK
authors.lastname: Paul
authors.affiliation: Department of Agricultural Chemistry and Soil Science, Faculty of Agriculture, Bidhan Chandra Krishi Viswavidyalaya, Mohanpur, Nadia, West Bengal 741252, India.
authors.forename: D K
authors.initials: DK
authors.lastname: Das
authors.affiliation: Upper Assam Advisory Centre, Tea Research Association, Dikom, Assam 786101, India.
authors.forename: Romesh K
authors.initials: RK
authors.lastname: Boruah
authors.affiliation: Upper Assam Advisory Centre, Tea Research Association, Dikom, Assam 786101, India.
authors.forename: Indira
authors.initials: I
authors.lastname: Sonar
mesh_terms: D065966:Absorption, Physicochemical; D002104:Cadmium / Q000032:analysis / Q000737:chemistry*; D003198:Computer Simulation; D007194:India; D007700:Kinetics; D008422:Materials Testing; D008956:Models, Chemical; D015233:Models, Statistical; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis / Q000737:chemistry*; D013816:Thermodynamics
chemical_list: D012987:Soil; D012989:Soil Pollutants; D002104:Cadmium