BSc/MSc/BTech Chemistry Lab Expt: Verify the Freundlich and Langmuir Isotherms for the Adsorption of Oxalic Acid on Activated Carbon
VERIFY THE FREUNDLICH AND LANGMUIR ISOTHERMS FOR THE ADSORPTION OF OXALIC ACID ON ACTIVATED CARBON Aim: (i) To study the adsorption of oxalic acid on activated charcoal and to Verify (a) Freundlich adsorption isotherm and (b) Langmuir adsorption isotherm. (ii) To determine the strength of unknown oxalic acid using Freundlich adsorption. Principle: Freundlich adsorption isotherm gives the relationship between the amount of adsorbate (x) adsorbed by a particular mass (m) of the adsorbent and the equilibrium concentration (c) of the adsorbate at a particular temperature. Freundlich isotherm is x/m = Kc 1/n log x/m = log K + (1/n) log c where, K and n are constants. If the plot of log (x/m) against log c is a straight line, it means that the adsorption follows Freundlich adsorption isotherm. Since (x/m) and c are fractions (<1), log (x/m) and log c will be negative values. To make it easier, plot with the positive quantities. - log (x/m) = -log K + (1/n) (-...