Dissertation (Msc Chemistry)The adsorption efficiency of Vangueriainfausta fruit pericap in the removal of Congo red dye from aqueous solution is investigated through batch experiments. Optimum conditions for adsorption process were determined by varying parameters pH, biosorbent dosage, contact time, initial congo red concentration and temperature. The physical characterisitics of the treated and untreated biosorbent were identified using Brunauer–Emmet–Teller (BET) method. Morphology of biosorbent wasviewed using Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). Chemical characterisitics were determined by Fourier Transform Infaredspectrometer (FT-IR) and Energy Dispersive Xray spectrometer (EDX). Quantification of dye was carried out using Ultraviolet-Visible Spectrophotometer. For explanation of the adsorption process, Freundlich and Langmuir isotherm models were used. Pseudo-first and second order was studied for adsorption mechanism and thermodynamic studies were investigated for testing spontaneity of adsorption. Desorption studies were carried out for the regeneration of the biosorbent after use. Adsorption was effective at pH 2, biosorbent dosage of 0.7 g, 180 minutes contact time, initial dye concentration of 10 mg/L at 55℃. The adsorption efficiency for the treated and untreated biosorbentwas92.3% and 50.3% respectively. The negative values of ΔG°(-5.78, -6.57, -7.37, -8.16, -8.95, -9.74 and -10.53 kJ/mol at 25, 30, 35, 40, 45, 50, 55 ℃ respectively) shows spontaneitywhile the positive values of ΔH°(41.42 kJ/mol) and ΔS (158.32 J/mol.K) depicts that adsorption was endothermic in nature with increase in randomness of the molecules. The adsorption processwas well explained by pseudo second order kinetics and the experimental data best fitted to the Langmuir isotherm model. The results depict that, the treated adsorbent from Vangueriainfaustais more effective in the removal of Congo red dye from aqueous solution.