Synthesis of Hybrid Ion Exchanger for Rhodamine B Dye Removal: Equilibrium, Kinetic and Thermodynamic Studies

A systematic method was employed to synthesize organic–inorganic-based hybrid ion-exchanger for the removal of rhodamine B dye from aqueous solution. Ion exchange capacity of the hybrid ion exchanger was found to be 2.4 mequiv/g. The morphology, chemical structure, and elemental analysis of the synthesized hybrid ion exchanger were investigated by SEM, FTIR, and EDS analytical techniques. Effects of different reaction parameters such as contact time, temperature, and pH were also investigated. The adsorption kinetics of rhodamine B molecules onto synthesized hybrid ion exchanger were studied and compared using psudo-first-order and pseudo-second-order, and it was found that pseudo-second-order best reprented the adsorption process. The Weber–Morris intraparticle diffusion result showed that intraparticle diffusion is not the rate limiting step. The adsorption isotherm model Langmuir, Freundlich, Dubinin–Radushkevich, Tempkin, and Redlich–Peterson isotherms were studied, and it was found that the Langmuir is the best-fitting models for the experimental results. An increase in temperature resulted in a decrease in rhodamine B dye removal, suggesting that the adsorption process was exothermic. Maximum dye removal was found to be 98.3%. The kinetics of adsorption followed a pseudo-second-order rate equation

Ecological risk assessment of metals in roadside agricultural soils: A modified approach

<p>The threat of metal contamination of roadside agricultural soils poses severe ecological risks throughout the globe due to dual contamination by intensive agriculture and traffic-related activities. Therefore, the present study was conducted to assess ecological risks posed by metals (Cd, Co, Cr, Cu, Fe, Mn, Pb, and Zn) in intensively cultivated roadside agricultural soils of Punjab, India. The results of the contamination assessment factors <i>i.e.</i> Contamination Factor (CF) and Enrichment Factor (EF) indicated that the studied soils were moderately to highly contaminated with metals. It was observed that the Modified Risk Index (MRI), which is based upon EF, indicated the ecological risks of metals more efficiently than the traditional Ecological Risk Index (RI), which is based upon CF in the present study. The MRI values indicated that the metals posed considerable to high risk in 67.86% samples as compared to only 7.14% samples based upon RI values. Thus, MRI can be considered as a more efficient risk indicator in comparison to RI. Spatial distribution maps of MRI indicated to higher metal contamination in inner urban parts of study area due to higher traffic and industrial activities.</p