Tag: adsorption

Recent Articles-IJES

Kinetics of adsorption of crystal violet from aqueous solutions using different natural materials
Author(s)- Kinetics of adsorption of crystal violet from aqueous solutions using different natural materials

ABSTRACT

Adsorption studies of Crystal Violet (CV) on different natural materials were carried out by batch experiments. The parameter studied includes initial dye concentration, adsorbent dose, pH, contact time, agitation speed, particle size of adsorbent and temperature. The linear regression coefficient R2 was used to elucidate the best fitting isotherm model. All isotherm models, Langmuir (R2 = 0.982 to 0.999), Temkin (R2 = 0.973 to 0.998) and Freundlich (R2 = 0.98 to 0.998 and n = 1.886 to 2.294) were found to be best fitting models.  The monolayer (maximum) adsorption capacities (qm) were found to be between 142.857 to 250 mg/g for natural adsorbents under study. Lagergen pseudo -second order model best fits the kinetics of adsorption. The correlation coefficient R2 for second order adsorption model has very high values of R2 for all absorbents (R2 ≈ 0.998) and qe(the) values are in good agreement with with qe(exp) showed that adsorption of CV on these natural materials follwed  second order kinetics and chemosorption playing role in rate determining step. Intra particle diffusion plot showed boundary layer effect and larger intercepts indicates greater contribution of surface sorption in rate determining step. pH was found to be an  important factor in controlling the adsorption of cationic dye. Adsorption of CV on adsorbents was found to increase on increasing pH, increasing temperature and decreasing particle size. Thermodynamic analysis showed that adsorption was favourable and spontaneous, endothermic physical adsorption and increased disorder and randomness at the solid- solution interface of CV with biosorbents. Mangrove plant leaf powder was found have excellent adsorption capacity towards CV than other natural materials under study.

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Recent Articles-IJES

Preparation of Carbonaceous Heavy Metal Adsorbent from Shorea Robusta Leaf Litter Using Phosphoric Acid Impregnation
Author(s)- Surya Narayan Dash, Ramachandra Murthy.V

ABSTRACT

In the present study, Shorea Robusta leaf litter, a non-convectional material, is proposed as a novel material for preparation of carbonaceous adsorbent impregnated with phosphoric acid, used for the reduction of Zinc and Copper metal ions from aqueous phase. For batch process, operating variables studied were adsorbent dose, contact time, initial metal ion concentration, pH and temperature. Sorption experiments indicated that the sorption capacity was dependent on operating variables and the process was strongly pH-dependent. Kinetic measurements showed that the process was uniform and rapid. In order to investigate the mechanism of sorption, kinetic data were modeled using the pseudo-first-order and pseudo-second-order kinetic equations, and intra-particle diffusion model. Among the kinetic models studied, the pseudo-second-order equation was the best applicable model to describe the sorption process. Equilibrium isotherm data were analyzed using the Langmuir, Freundlich and Temkin isotherms. The Langmuir model yields a much better fit than the Freundlich and Temkin models. Isotherms have also been used to obtain the thermodynamic parameters such as free energy, enthalpy, and entropy of sorption. The value of H is negative, indicating that the Zinc and Copper adsorption by the simulated activated carbon are exothermic in nature.

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