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.
