Cadmium mobility in sediments and soils from a coal mining area on Tibagi River watershed: Environmental risk assessment (original) (raw)

Cadmium Sorption by Some Alkaline Soils of North-West India

The 2005 Annual Meeting, 2005

Cadmium adsorption on five alkaline soils of north-west India followed Langmuir equation. The analogues shape of Linear Langmuir plot in each soils at 298 and 313 0 K elucidate that temperature does not change the nature of reaction but influence the bonding energy constant and adsorption maxima for Cd ion. The magnitude of adsorption maxima enhanced with increase in CaCO 3 and organic content in soils. The positive and constant value of differential isosteric heat of adsorption (ΔH) on each soil between 298 and 313 o K elucidate that adsorption of Cd is an endothermic process which leads to precipitation of Cd rather than physical adsorption. However, the variation of ΔH within different soils might be due to variation in their physico-chemical characteristics. Solubility isotherm diagram revealed that CdCO 3 reaction product formed in equilibrated soil-Cd system used for adsorption study. It was concluded from Linear Langmuir plots, differential isosteric heat of adsorption ΔH and solubility isotherm studies that adsorption of Cd in alkaline soils occurred due to precipitation of CdCO 3 mineral.

Study of Cadmium Desorption Kinetics from Riverine Sediments

2021

In natural streams, the majority of heavy metal ions are generally associated ‎with ‎sediment particles. Under some environmental conditions, these metal ions may release from ‎the ‎sediment particles.‎ In such conditions, the desorption rate of heavy metals is very important for decision-makers of ‎water quality assessment. In this study, the effect of cadmium desorption ‎from the river bed ‎sediments has been ‎experimentally investigated. Artificially contaminated sediments were used ‎for performing batch desorption ‎experiments. The experiments were conducted by adding 1 gr of contaminated ‎sediment (D50 = 0.53 mm) with a known concentration and shaking until observing a ‎roughly ‎constant cadmium concentration in the solution. It was concluded that the cadmium ions were strongly bond to the river bed sediment; meanwhile, at the ‎equilibrium time, up to about 7 to 29 percent of cadmium ions were ‎released from the‎ artificially contaminated sediments. The experiments were followe...

Sorption of cadmium in some arable and forest soils

Journal of Radioanalytical and Nuclear Chemistry, 2000

The behavior of cadmium labeled with 109 Cd in different depth horizons of arable and forest soils were studied under static (batch) conditions in three interconnected processes, which consist of sorption, desorption and extraction. In the sorption, Cd 2+ was applied in the aqueous calcium nitrate solution. Both untreated soils and peroxide treated soils were used in order to remove organic matter from some of the soil samples used in parallel. The influence of the V/m ratio on the sorption coefficients was investigated in preliminary experiments with untreated soils. Contrary to the usually short-term sorption, a long-term sorption of cadmium was investigated in untreated and treated soil horizons, which lasted more than fortnight. Kinetic studies of sorption were carried out and cadmium concentration dependence in aqueous phase of the second order kinetic constants was observed. For evaluation of sorption and desorption processes Freundlich isotherms were used. It was found that the Freundlich adsorption intensity coefficient is more time dependent than the absorption capacity coefficient, and the sorption itself consists of rapid and slow processes according to the soil constituents. Desorption and extraction processes revealed the possibility of cadmium recovery from various soil horizons. Based on the obtained results two-or three-stage theory of cadmium retention in soils was proposed. Some new insight into the role of organic matter in the sorption/desorption process of cadmium is also presented.

Thermodynamics of Cadmium Sorption on Different Soils of West Bengal, India

The Scientific World Journal, 2014

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 ( 0 ), Gibbs free energy at a particular temperature (Δ 0 ), and change of enthalpy (Δ 0 ) and change of entropy at temperature (Δ 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 0 , Δ 0 , Δ 0 , and Δ 0 were increased on reaction temperatures. The spontaneous sorption reaction can be concluded due to high values of Δ 0 . The positive values of Δ 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.

Adsorption of cadmium on bed sediments of river Hindon: Adsorption models and kinetics

Water, Air, & Soil Pollution, 2002

The adsorption characteristics of cadmium on bed sediments of river Hindon in western Uttar Pradesh (India) have been studied. The effect of various operating variables, viz., initial concentration, solution pH, sediment dose, contact time, particle size and temperature has been studied. The optimum equilibration time was found to be 60 min, which was independent of initial concentration of cadmium ions. The adsorption curves were smooth and continuous leading to saturation, suggesting the possible monolayer coverage of cadmium ions on the surface of the adsorbent. The adsorption of cadmium increased with an increase in pH. Furthermore the adsorption of cadmium increased with increasing adsorbent concentration and decreased with adsorbent particle size. The important geochemical phases, iron and manganese oxide, support the adsorption of cadmium ions. The adsorption data were analysed using the Langmuir and Freundlich adsorption models to determine the mechanistic parameters related to the adsorption process. Thermodynamic parameters, viz., free energy change, enthalpy change and entropy change, were also determined. The negative values of free energy change ( G • ) indicated the spontaneous nature of the adsorption and positive values of enthalpy change ( G • ) suggested the endothermic nature of the adsorption process. The intraparticle diffusion of cadmium through pores in the adsorbent was found be the main rate-limiting step.

Study of multi-stage cadmium adsorption by riverine sediments

Advances in Environmental Technology, 2020

Most riverine sediments have the high capability to adsorb and store heavy metal ions. In the present study, the adsorption capacity of the bed sediments collected from the Karaj River (Iran) were experimentally studied for cadmium ion adsorption. Multi-stage batch adsorption experiments were carried out for a constant sediment concentration of 20 g/L and different initial cadmium concentrations of 0.2, 0.5, 1, 10, 20, and 50 mg/L. The cadmium solutions with known concentrations were added to the bed sediment with the mean diameter of 0.53 mm in five stages to characterize the capacity of the sediments to adsorb cadmium. The batch adsorption experiments were conducted as both kinetics and equilibrium. The results showed that by adding cadmium ions to the sediment at each stage, the adsorption capacity was less than the previous stage, and for a cadmium concentration of 0.2 mg/L, the adsorption percent and the amount of adsorbed cadmium was reduced from 88 to 70% and 9 to 6.8 mg/kg, respectively. These changes decreased with increasing initial Cd concentrations. This process is useful for seasonal rivers in which a certain concentration of heavy metal pollution may occasionally flow over the bed.

Cadmium desorption behaviour in selected sub-tropical soils: Effects of soil properties

Journal of Geochemical Exploration, 2014

To predict the environmental fate and mobility of contaminants, it is critical to study desorption behaviour of contaminants in soil system. Cadmium (Cd) desorption kinetics studies were conducted in ten sub-tropical soils of the northern part of Iran, with a wide range of physico-chemical properties. Treatments consisted of two levels of cadmium (15 and 30 mg kg −1 as CdCl 2 ). Soils were incubated at 20% moisture (w/w) level and 25 ± 1 ºC. After weeks, cadmium desorption pattern was investigated by Diethylene Triamine Pentaacetic Acid (DTPA) extraction with equilibration periods from 30 to 960 min. Results showed that two constant rate, parabolic diffusion and simple Elovich equations best described Cd desorption in these soils. The coefficients of kinetic equations had significant correlation with each other. The findings of this investigation indicated that pH, cation exchange capacity, organic matter, and oxalate extractable Fe are the most important soil characteristics in controlling Cd desorption behaviour in sub-tropical soils.

Adsorption of Cadmium, Copper and Chromium by an Agricultural Soil Impacted by Mining Activities

Water, Air, & Soil Pollution, 2017

Batch adsorption studies for cadmium (Cd), copper (Cu) and chromium (Cr) onto an agricultural soil impacted by mining activities were conducted in singleand multi-component systems. The effect of initial concentration, pH and competing ions (Fe 3+ , Ca 2+ , Co 2+ , Mg 2+ , K + , Ni 2+ and Zn 2+) on adsorption was studied. The soil exhibited high adsorption capacities for the elements at all initial concentrations with the adsorption process better described by the Freundlich isotherm. Adsorption was found to proceed via an ion exchange mechanism. The pseudo second-order kinetic model described the adsorption of the elements (R 2 > 0.999), indicating a chemisorption process. The adsorption of Cd increased with pH in both systems while that for Cu decreased. The adsorption of Cr decreased with pH in the single-component system, but increased in the multicomponent system. The adsorption of Cd was affected more by competing ions while Cu and Cr were not significantly affected (p > 0.05). Elemental speciation under varying conditions was studied using the PHREEQC geochemical modelling code. The observed high capacity of the soil for the elements pointed to the soil's potential as a repository, a feature that would change depending on the speciation of the elements and soil conditions.