:The paper includes utlization of zeolite as potential adsorbent to remove a hazardous malachite green from waste water. The adsorption studies were carried out at 298, 308 and 318 K and effects of temperature, contact time, initial concentration on the adsorption were measured. On the basis of adsorption data Langmuir and Freundlich adsorption isotherm model were also confirmed. The equilibrium process was described well by Freundlich isotherm model, showing a selective adsorption by irregular energy of zeolite surface. From determined isotherm constants, zeolite could be employed as effective treatment for removal of malachite green. From kinetic experiments, the adsorption process followed the pseudo second order model, and the adsorption rate constant (k2) decreased with increasing initial concentration of malachite green. Thermodynamic parameters like activation energy, change of free energy, enthalpy, and entropy were also calculated to predict the nature adsorption. The activation energy calculated from Arrhenius equation indicated that the adsorption of malachite green on the zeolite was physical process. The negative free energy change (ΔG o =-6.47~-9.07 kJ/mol) and the positive enthalpy change (ΔH o = +32.414 kJ/mol) indicated the spontaneous and endothermic nature of the adsorption in the temperature range 298~318 K.
Adsorption of metanil yellow onto granular activated carbon were studied in a batch system. Various operation parameters such as adsorbent dosage, pH, initial concentration, contact time and temperature were optimized. Experimental equilibrium adsorption data were analyzed by Langmuir and Freundlich adsorption isotherm. The equilibrium process was described well by Freundlich isotherm model. From determined separation factor (1/n), adsorption of metanil yellow by granular activated carbon could be employed as effective treatment method. By analysis of kinetic experimental data, the adsorption process were found to confirm to the pseudo second order model with good correlation and the adsorption rate constant (k2) decreased with increasing initial concentration. Thermodynamic parameters like activation energy, change of free energy, enthalpy, and entropy were also calculated to predict the nature adsorption in the temperature range of 298∼318 K. The activation energy was determined as 23.90 kJ/mol. It was found that the adsortpion of metanil yellow on the granular activated carbon was physical process. The negative Gibbs free energy change (ΔG = -2.16∼-6.55 kJ/mol) and the positive enthalpy change (ΔH = +23.29 kJ/mol) indicated the spontaneous and endothermic nature of the adsorption process, respectively.
Allura Red (AR) is a water-soluble harmful tar-based food colorant (FD & C Red 40). Batch adsorption studies were performed for the removal of AR using bituminous coal based granular activated carbon as adsorbent by varying the operation parameters such as adsorbent dosage, initial concentration, contact time and temperature. Experimental equilibrium adsorption data were analyzed by Langmuir, Freundlich and Temkin isotherms. The equilibrium process was described well by Freundlich isotherm. From determined separation factor (RL), adsorption of AR by granular activated carbon could be employed as effective treatment method. Temkin parameter, B was determined to 1.62∼3.288 J/mol indicating a physical adsorption process. By estimation of adsorption rate experimental data, the value of intraparticle diffusion rate constant (km) increased with the increasing adsorption temperature. The adsorption process were found to confirm to the pseudo second order model with good correlation. Thermodynamic parameters like change of free energy, enthalpy, and entropy were also calculated to predict the nature adsorption in the temperature range of 298∼318 K. The negative Gibbs free energy change (ΔG =-2.16∼-6.55 kJ/mol) and the positive enthalpy change (ΔH = + 23.29 kJ/mol) indicated the spontaneous and endothermic nature of the adsorption process, respectively.
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