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Ram, Bali
- Adsorption-Desorption Studies of Cadmium in Three Different Soil Orders
Authors
1 Department of Soil Science and Agricultural Chemistry, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi-221 005, IN
2 National Bureau of Soil Survey & Land Use Planning (ICAR), Amravati Road, Nagpur-440 033, IN
3 Department of Chemistry, Hindu University, Varanasi-221 005, IN
4 Division of Soil Biology, Indian Institute of Soil Science, Nabibagh, Berasia Road, Bhopal-462 038, IN
Source
Nature Environment and Pollution Technology, Vol 13, No 3 (2014), Pagination: 559-564Abstract
Sorption isotherms have been widely used to assess the heavy metals retention characteristics of soil particles. Adsorption behaviour of cadmium (Cd) in soils is an important process which exerts a major influence on its uptake by plant ischolar_mains. Desorption behaviour of the retained metals, however, usually differ from that of adsorption, leading to a lack of coincidence in the experimentally obtained adsorption and desorption isotherms. Three soils differing in physico-chemical properties (pH 5.7 to 8.2) and varied taxonomy (Typic Ustochrepts, Typic Rhodustalfs and Entic Chromusterts), were subjected to Cd treatment at various concentrations (0, 2, 4, 8, 15, 30, 45, 75 mg Cd/L). The Cd adsorbed by each soil was calculated as the difference between the amount of Cd present in the solution initially and that remaining after equilibration. Immediately after adsorption, desorption took place using successive dilution method with five consecutive desorption steps. Both, Cd adsorption and desorption data were described by Freundlich equation. The adsorption and desorption reactions, however, did not provide the same isotherms, indicating that hysteresis occurred in Cd adsorption-desorption process. Results indicated that the adsorption capacity of the soils for Cd increased with an increase in the pH or alkalinity of the soils. The rate of adsorption was, however, found to decrease with increased pH. But no specific trend was observed in case of desorption. All the three soils used in this study followed Freundlich adsorption isotherms. The adsorption data, in general, indicated that Cd was in a fixed form at higher pH levels. The Cd adsorption was in the order of Entic Chromusterts > Typic Ustochrepts > Typic Rhodustalfs.Keywords
Adsorption-Desorption, Cadmium, Sorption Isotherms, Soil Orders.Full Text
- Hydrodynamic and Electro-Osmotic Studies on Transport through Nylon-66 Membrane Using Aqueous Aluminium Nitrate as Permeant
Authors
Source
International Journal of Innovative Research and Development, Vol 4, No 3 (2015), Pagination:Abstract
The object of this work was to study the transport phenomena across the nylon-66 membrane of aqueous aluminum nitrate as permeants. Hydrodynamic and electro-osmotic permeability measurements of water and aqueous solutions of Al (NO3)3.9H2O in the concentration range of 10-4 M to 10-3 M have been made. The data obtained have been used to determine the transport equation using the theory of non-equilibrium thermodynamics. Streaming current generated during the transport of various permeants was also measured and its dependence on pressure investigated. Phenomenological coefficients have been determined using the transport equation and Saxen’s relationship verified. Zeta potentials have been evaluated using electro-osmotic permeability and membrane-permeant conductance data. It has been observed that hydrodynamic and electro-osmotic permeabilities depend linearly on applied pressure difference and potential difference respectively.