Effect of substituents types on the adsorption of β-naphthol aniline derivatives over the activated carbon

Abstract

This study included investigation of the adsorption of a number of azo dyes (β-naphthol with aniline and some of its substations).(H,o-NO2,p-NO2 ,m-NO2 ,o-CH3 , m-OH , o-OH ,p-OH) and the effect of substitute in the dye on the percentage ratio of adsorption in addition to the effect of concentration , temperature and pH of the medium.The adsorption equilibrium constant is determined from the ratio between the adsorbed and the un adsorbed dyes . The study was conducted at different temperatures with in the range (10-60)C°¬.This study showed that the optimum condition of adsorption are, concentration arrange (4*10-5 - 1*10-5 )M, and pH range (3.1-3.7) with a best time for reaching equilibrium is (70) min. with a shaking speed (40)rps. The thermodynamic parameters (ΔH, ΔG, and ΔS) are calculated . The values of (ΔH)concluded that the process of adsorption of the dyes on activated carbon is exothermic and physical in nature . The negative values of (ΔG) show that the adsorption process of the dyes is spontaneous in most cases. The (ΔS)values are not affected within the studied temperature range but are changed with varying the type and position of the substitutions.The data collected are applied to adsorption isotherm models of Freundlich and Longmuir which show that both models are correlated satisfactory. Overall results reveal that the inter and intra molecular hydrogen bonding ,other attracting forces , resonance ,inductive effect and steric factor have great influence on the adsorption efficiency.