ADSORPTION OF ORGANIC ACIDS ON CERTAIN SUBSTRATES

Adsorption is of great importance in catalytic chemical reactions. It is the first step in many inorganic, organic and biochemical reactions. Thousands of different enzymes are present in animal and plant bodies. These enzymes act as biocatalysts and convert substances into different products using adsorption as a starting point in the reaction. Adsorption is an exothermic process and may involve forces like Coulombic and Van der Waals. It may be physical or chemical, depending upon the nature of the forces involved in the process. The present investigation was limited to the study of adsorption of (a) low carbon fatty acids like acetic, oxalic, tartaric and citric acids and (b) high carbon fatty acids like palmitic, oleic and stearic acids, on alumina, cellulose and starch. Acetic acid is a short chain monocarboxylic acid. Palmitic, oleic and stearic acids are long chain monocarboxylic acids. Tartaric and oxalic acids are dicarboxylic acids and citric acid is a tricarboxylic acid. Different kinds of fatty acids were included in the study to see the effect of the hydrocarbon chain length and the number of carboxylic groups on the acid in the adsorption process. Titrimetric and gravimetric methods were employed to measure the rate of adsorption of fatty acids. The titrimetric method was used in case of fatty acids soluble in water, like acetic, oxalic, tartaric and citric acids. The gravimetric method was used for acids soluble only in organic solvents, like benzene. The latter acids included palmitic, oleic and stearic. All experiments to measure the adsorption of fatty acids by alumina, cellulose and starch were conducted at room temperature.