Effect of Substituents Type on the Adsorption of Aromatic Carboxylic Acids and their Relation to Concentration, Temperature and pH

The study involved investigation of the adsorption of aromatic carboxylic acids carrying various substituents such as OH, NH2 and SH. The effects of concentration, temperature and pH were induced. The results indicated that increasing the temperature from 15 to 30 oC reduces the adsorption ratio, while dilution of carboxylic acid solution to a little value showed high adsorptivity. This point is of a valuable interest because most of carboxylic acids as pollutants present in a minute amounts.
Effect of pH showed that the natural pH is the best condition for the removal which is arreptable for the treatment of industrial water. According to the literature we assumed that after one hour of extraction the system will be in equilibrium. Therefore, from this point we determined the thermodynamic functions for each system under investigation. The study revealed that the hydrogen bond present in the system and other attraction forces with the resonance have great effect on the adsoption.