Nano zerovalent iron (NZVI) adsorption performance on acidic dye 36 removal: Optimization of effective factors, isotherm and kinetic study

This study focused on the efficiency of nano zerovalent iron (NZVI) for degrading industrial dye (acidic dye 36). To elucidate NZVI characteristics, some advanced analytical experiments such as FTIR, TGA, EDS, XRD, TEM as well as SEM were measured. The performance evaluation of the adsorbent was carried out within variety of adsorption influencing parameters, including pH, contact time, initial dye dosage and NZVI dosage) with the assistance of central composite design (CCD) as a strong tool suggested by response surface methodology software. The results gained through CCD illustrate that the quadratic model is the suggested one with adjusted R-2 =0.896 and predicted R-2 =0.723. The little difference between actual and predicted values proves the power of the model to satisfactorily and reliably predict the efficiency removal. Applying mathematical equations reveal that initial dye dosage and interactive contribution of pH and dye dosage are the most influential single and combined factors, respectively. The optimized condition obtained by RSM for NZVI adsorption process was determined at pH = 5.5, NZVI = 0.5, dye solution = 30mg/L, and 90s of contact time. The adsorption kinetic was performed, introducing the second order as the best one and the Langmuir isotherm gained high agreement with experimental data as well.