Development Of Various Modified Maize Cob As Adsorbents For Methylene Blue Dye Wastewater Treatment

The adsorption of basic dye, Methylene Blue (MB) onto raw maize cob (RMC), acid modified maize cob (AMMC), ferric oxide (Fe3O4), raw maize cob impregnated with ferric oxide (RMC-Fe3O4) and acid modified maize cob impregnated with ferric oxide (AMMC-Fe3O4) have been investigated in this study. The effects of pH, adsorbent dosage, initial dye concentration, contact time and temperature on dye concentration removal and COD reduction were investigated by screening process and optimized by response surface methodology (RSM). All the effects showed statistical significance and the adsorption process using AMMC-Fe3O4 showed the highest effectiveness among the five adsorbents. The adsorption process using AMMC-Fe3O4 obtained the highest percentage of dye concentration removal (99.63%) and COD reduction (99.48%) at the optimum conditions with 0.75 g/100 mL of adsorbent dosage, pH 10.31, 156 mg/L of initial dye concentration for 36 minutes under 38.40 oC. The kinetic experimental data were analyzed using four kinetic equations which include pseudo-first-order model, pseudo-second-order model, external diffusion model and intraparticle diffusion model to determine the mechanism of adsorption and potential rate-controlling step. All five adsorbents showed the best fit with pseudo-second-order kinetic model. The experimental equilibrium data were tested on three isotherm models which included Langmuir isotherm, Fruendlich isotherm, and Temkin isotherm