Adsorptive Removal Of Methylene Blue Dye From Aqueous Solution By Sulfuric Acid Modified Avocado Seed

Abstract

Dyes are complex organic compounds which are widely used in textile, printing, leather, cosmetic and paper industries and hence produce large amount of dye bearing liquid effluents The aim of this study was to examine the removal of methylene blue dye from aqueous solution by using activated avocado seeds modified using sulfuric acid. Various operation parameters such as adsorbent dosage, contact time, effect of pH, initial concentration and temperature were studied and optimized. The optimum dose, pH, concentration, contact time, and temperature were found to be 6g/L, 8, 5mg/L, 1hr and 40°Cfor carbonized avocado seed,10% carbonized avocado seed activated and 20% carbonized avocado seed activated by sulfuric acid. The result showed that the percentage removal of 78.6%, 83.7% and 87.2% for carbonized avocado seed,10% carbonized avocado seed activated and 20% carbonized avocado seed activated by sulfuric acid respectively. The functional groups on the surface of the adsorbents carbonized avocado seed,10% carbonized avocado seed activated and 20% carbonized avocado seed activated(C-H,C=O,C-O,) was investigated from FTIR analysis. The experimental data of adsorption in equilibrium condition were tested by isothermal adsorption like Langmuir and Freundlich at different conditions. According to correlation coefficient both Langmuir and Freundlich model were fitted to the adsorption data of MB dye on to carbonized avocado seed,10% carbonized avocado seed activated and 20% carbonized avocado seed activated surfaces respectively. Comparing the two, Freundlich model is more fitted than Langmuir models. Therefore, the adsorbents showed that MB dye removal with 3.48, 8.92 and 17.12 mg/g adsorption capacity for carbonized avocado seed, 10% carbonized avocado seed activated and 20% carbonized avocado seed activated respectively. The adsorption kinetics was best described by the pseudo-second order model which was based on the assumption that the adsorption rate might be largely controlled by a chemisorption process. Finally, the adsorption efficiency of the activated carbon modified by 20% sulfuric acid was found to be greater than modified by 10% sulfuric acid, while the unmodified avocado seed showed least adsorption efficiency.