Kinetic and Thermodynamic Study of the Adsorption of some Organic Acids by MnO2

Abstract

In this research work, the adsorption efficiency of three structurally related acids namely, glycolic, mandelic and benzylic acids by MnO2 from their aqueous solutions is investigated.The study is aimed at developing a better understanding of the adsorption mechanism regarding the molecular level. The experiments were achieved as batch methods.The factors affecting the adsorption efficiency such as; contact time, initial concentration, initial pH of the acid medium and temperature are studied. The results obtained showed that, the increase of initial concentration increases the adsorption efficiency. The initial pH of the medium plays an important role in controlling the attachment of acid molecules on the solid surface of MnO2. The highest adsorption efficiency is observed in the acid medium (natural pH of the acid solutions).This study proved that, the acid is connected to the solid surface of absorbent in its anion form.The thermodynamic functions of adsorption are estimated at different initial concentrations (0.005-0.05 N). The study also included the application of the two kinetic models on the adsorption data namely; the pseudo first order and pseudo second order equations. The investigation is performed at certain concentration and various temperatures. The results denoted that, the studied systems are better fit the second order model.