RESUMO
This study evaluates the adsorptive capacity of elephant grass (EG) in the removal of Methylene blue (MB) dye from wastewater sourced from two major local dyeing industries in Ogun State, Nigeria. Batch adsorption method was used to determine the optimum conditions, characterization of the adsorbent, equilibrium Isotherm models, kinetics and thermodynamics studies were conducted to evaluate the nature of the adsorption process. The optimum adsorption conditions obtained for the standard solution of MB dye were; pH 7, Temp 40 °C, contact time 180 min and adsorbent dosage 2.0 g. The presence of oxygen containing functional groups and shift or disappearance of bands in the FTIR suggested the suitability of EG for the process. The SEM of EG revealed presence and disappearance of pores before and after the adsorption process. The mechanism of this adsorption is complex, the adsorption data is best fitted to Langmuir isotherm, the mean adsorption energy E (≤6.455 kJ/mol), and activation energy (10.84 kJ/mol) represents physical process but, the thermodynamic studies revealed spontaneity (ΔG° -15.93 to -14.26 kJ mol-1), randomness, and endothermic (ΔH° 40.1 kJ/mol) nature, representing chemisorption. Therefore, local dyers around the study sites can make use of the freely available EG for the remediation of their wastewater.
Elephant grass (EG) abundantly thrives on the study sites where dye wastewater is released by local dyers. This serves as the impetus for this research as no other plants thrive on the dye-polluted environment. A favorable adsorption was obtained with EG as adsorbent for the Methylene blue (MB) dye that is a major constituent of the wastewater from the two major local dyeing industries investigated. Therefore, this study provides scientific support for the local dyers around the study sites to make use of the freely available EG for the remediation of their wastewater.
