Langmuir, freundlich, temkin and dubinin radushkevich. Pdf abstract the purpose of this study was to investigate the. Sparks, in environmental soil chemistry second edition, 2003. In many textbooks freundlich isotherm is presented as an empirical equation with no or limited explanation on the physical significance of both k and or b 9, and 10 11. Freundlich isotherm equilibrium equastions in determining effectiveness a low cost. Freundlich isotherm equilibrium equastions in determining. Langmuir freundlich isotherm as the base model to describe all our arsenate adsorption data. A general form of langmuir freundlich isotherm equation for. The amount of n in the freundlich equation was table 5. In general, k decreases and m increases with increasing temperature, which equates to less equilibrium adsorption.
The freundlich equation is simple, however, it does not exactly describe the isotherm in a wide pressure range. The freundlich equation or freundlich adsorption isotherm, an adsorption isotherm, is an. Results were analyzed by the freundlich and langmuir equation at different temperatures and determined the. Modelling of single and binary adsorptions of heavy metals. The hill, freundlich and bet equations were ap propriate models. Of the four adsorption isotherm, the r2 value of langmuir isotherm model was the highest. Journal of contaminant hydrology auburn university. The freundlich equation, which was first used to describe gas phase adsorption and solute adsorption, is an empirical adsorption model that has been widely used in environmental.
Then the equation appeared to be sometimes useful in theoreticalconsiderations and it can be derived using the methods of statistical mechanics. Freundlich equation an overview sciencedirect topics. The derivation of srs equation was based on the assumption of an exponential distribution of. A volume of 500 ml is placed in each flask, and the waste has an initial cod of 100 mgl. Plot the data according to freundlich isotherm and determine the values for the constants n and k f. It was observed that the freundlich isotherm model described the adsorption process with high coefficient of determination r2, better than the. Pdf freundlich and langmuir adsorption isotherms and kinetics. Pdf langmuir, freundlich and bet adsorption isotherm studies. Freundlich isotherm is shown by equation 2 the following. This equation is known as the freundlich adsorption equation because freundlich popularized its. Use of the freundlich equation to describe zinc adsorption xdesorption 0 on soils. Adsorption data were adjusted to five isotherm models. Freundlich, temkin and dubininradushkevich drk isotherms. Temkin and dubininradushkevich, in order to determine which.
1249 330 822 492 728 254 114 936 1559 981 918 1251 1481 992 1395 1064 623 1113 678 1351 433 1478 911 647 1381 289 428 527 1167 668 1436 276