Sangeeta Sahu; Madhurima Pandey; Shilpa Sharma
Abstract
Cadmium is biopersistant. Significant concentration of cadmium is released in the environment by various industrial activities worldwide. Therefore, removal of cadmium from waste water is now receiving greater attention from researcher various techniques for cadmium metal removal from industrial effluents ...
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Cadmium is biopersistant. Significant concentration of cadmium is released in the environment by various industrial activities worldwide. Therefore, removal of cadmium from waste water is now receiving greater attention from researcher various techniques for cadmium metal removal from industrial effluents has been developed. These techniques are: chemical precipitation, chemical reduction, ion exchange, evaporation, membrane processes, and adsorption. Each method has its own advantages and disadvantages among these techniques; adsorption of cadmium metal by using various materials was proved to be a very effective method. Moreover, research is needed to find the commercial and practical utility of low-cost adsorbents.From the current review, adsorption seems to be t he best alternative, help to develop new metal remediation technology and to study the scientific advances of recent years in this area.
Vandana Singha; Sadanand Pandeya;Rashmi Sanghib; Somit Kumar Singha
Abstract
In continuation to our recent study on the synthesis and characterization of starch-silica nanocomposite, in the present study the nanocomposite has been evaluated for the removal of Cd(II) from the aqueous solution. The conditions for the sorption have been optimized and kinetic and thermodynamic studies ...
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In continuation to our recent study on the synthesis and characterization of starch-silica nanocomposite, in the present study the nanocomposite has been evaluated for the removal of Cd(II) from the aqueous solution. The conditions for the sorption have been optimized and kinetic and thermodynamic studies were performed to understand the adsorption behaviour of the composite. Though the cadmium sorption by the nanocomposite takes place in wide pH range, pH 7.5 was found most favorable and at this pH the adsorption equlibrium data were modeled using the Langmuir and Freundlich isotherms at 10°C, 20°C, 30°C and 40°C. At all the temperatures, the data fitted more satisfactorily to Langmuir isotherm indicating unilayer adsorption. Based on Langmuir model, Qmax was calculated to be 769.23 mg/g. The adsorption showed pseudo second order kinetics with a rate constant of 5.65 × 10 -5 g mg -1 min -1 (at 100 mg/L initial Cd(II) concentration) indicating chemisorption. The thermodynamic study revealed the endothermic and spontaneous nature of the adsorption. Effect of electrolyte on the adsorption was also studied. The nanocomposite was sucessfully recycled for six consecutive adsorption-desorption cycles with only a marginal loss in its efficiency indicating its high reusability. The composite was found to be a highly stable photoluminescent Cd(II) adsorbent which may be suitable for sensor applications in detecting the metal ions both in vivo and vitro as the material is natural polymer based.