N. K. Mondal

Eggshell Powder as an Adsorbent for Removal of Fluoride from Aqueous Solution: Equilibrium, Kinetic and Thermodynamic Studies

A new medium, eggshell powder has been developed for fluoride removal from aqueous solution. Fluoride adsorption was studied in a batch system where adsorption was found to be pH dependent with maximum removal efficiency at 6.0. The experimental data was more satisfactorily fitted with Langmuir isotherm model. The kinetics and the factor controlling adsorption process fully accepted by pseudo-second-order model were also discussed. Ea was found to be 45.98u2009kJmol-1 by using Arrhenius equation, indicating chemisorption nature of fluoride onto eggshell powder. Thermodynamic study showed spontaneous nature and feasibility of the adsorption process with negative enthalpy (∆H0) value also supported the exothermic nature. Batch experiments were performed to study the applicability of the adsorbent by using fluoride contaminated water collected from affected areas. These results indicate that eggshell powder can be used as an effective, low-cost adsorbent to remove fluoride from aqueous solution as well as groundwater.

Insight into adsorption equilibrium, kinetics and thermodynamics of lead onto alluvial soil

In the present study, adsorption of lead (II) ions from aqueous solution by alluvial soil of Bhagirathi River was investigated under batch mode. The influence of solution pH, sorbent dose, initial lead (II) concentration, contact time, stirring rate and temperature on the removal process were investigated. The lead adsorption was favored with maximum adsorption at pH 6.0. Sorption equilibrium time was observed in 60xa0min. The equilibrium adsorption data were analyzed by the Freundlich, Langmuir, Dubinin–Radushkevich and Temkin adsorption isotherm models. The kinetics of lead (II) ion was discussed by pseudo first-order, pseudo second-order, intra-particle diffusion, and surface mass transfer models. It was shown that the adsorption of lead ions could be described by the pseudo second-order kinetic model. The activation energy of the adsorption process (Ea) was found to be −38.33xa0kJxa0mol−1 using the Arrhenius equation, indicating exothermic nature of lead adsorption onto alluvial soil. Thermodynamic parameters, such as Gibbs free energy (∆G0), the enthalpy (∆H0), and the entropy change of sorption (∆S0) have also been evaluated and it has been found that the adsorption process was spontaneous, feasible, and exothermic in nature. The results indicated that alluvial soil of Bhagirathi River can be used as an effective and low cost adsorbent to remove lead ions from aqueous solutions.

Influence of Integrated Nutrient Management on Soil Properties of Old Alluvial Soil under Mustard Cropping System

Field experiments were conducted at the fields of Crop Research and Seed Multiplication Farm of Burdwan University, Burdwan, West Bengal, India during the winter seasons of 2005–2006, 2006–2007, and 2007–2008 in old alluvial soil (pH-6-7) to evaluate the influence of integrated nutrient management on soil physicochemical and biological properties under mustard (Brassica campestris cv. ‘B9’) cropping system. In the first year (2005–2006), seven varieties of mustard were cultivated under recommended dose of chemical fertilizer (100:50:50). In the second year of the experiment (2006–2007), six different doses of biofertilizer and chemical fertilizer were applied. In the third year (2007–2008), six different level of compost along with a combined dose of biofertilizer and chemical fertilizer (T3-3/4 Chemical fertilizer: 1/4 biofertilizer) were applied. The results indicated significant improvement in the soil quality by increasing soil porosity and water holding capacity significantly, as well as gradual build-up of soil macronutrient status after harvesting of the crop. Applications of biofertilizers have contributed significantly toward higher soil organic matter, nitrogen (N), available phosphorus (P), and potassium (K). The use of biofertilizers and compost have mediated higher availability of iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), and boron (B) in soil. The use of biofertilizers and compost significantly improved soil bacterial and fungal population count in the soil, thereby increasing the soil health.