Impact of surface functional groups on the adsorption of aliphatic organicacids from aqueous solutions on granular activated charcoal

Adsorption of aliphatic organic acid, such ar Formic, Acetic, Propionic and n-Butyric acids fi om aqueous solutions on the su;face of granular activat ed charcoal was studied as a function of stirring time, concentration of ad sorbate and evacuation temperature (105 degreesC, 300 degreesC and 800 degr eesC). Adsorption equilibrium war found to be established within four hours time in all cares of aliphatic organic acids having concentrations i.e. 0. 005M and 0.01 M at temperature of 25 degreesC, which may be due to the unif orm distribution of dive rites on the surface of adsorbent. Evacuation temperatures (105 degreesC, 300 degreesC and 800 degreesC) showe d a considerable positive effect on the extent of adsorption and it war fou nd that the higher adsorption of the organic acid on the sample evacuated a t 800 degreesC may be due to the decomposition of surface oxides and evolut ion of CO and CO2 at high evacuation temperature, which make the surface no n-polar and thereby increased surface area which result in greater adsorpti on of non-polar or weakly polar organic acid, because of high affinity for organic compounds whereas carbon possess surface functional group having hi gh affinity for water molecules, and thereby decreasing the effective diame ter of the pore opening which result in lower adsorption of organic compoun ds at 105 degreesC. The amount of adsorption of organic acids constantly in creases as the homologous series is ascending Linear form of Freundlich's a nd Langmuir equations were applied to the adsorption isotherms data and it was found that both the equations obeyed them well.