Preparation of cetyltrimethylammonium bromide modified montmorillonite nanomaterial for adsorption of a textile dye

The main aim of this investigation was to evaluate the efficacy of the cetyltrimethylammonium bromide (CTAB) modified montmorillonite (MMT) nanomaterial for the adsorption of Acid orange 7 (AO7) as an anionic dye in aqueous solutions. The decolorization efficiency (%) was first increased from 52.74% to 94.08% with increasing cation exchange capacity (CEC) from 0.5 to 1.0 CEC and then decreased to 74.89% with increasing the amount of added CTAB to 1.5 CEC. Response surface methodology (RSM) based on central composite design (CCD) was used to evaluate the effect of various operational parameters on the adsorption of AO7. Predicted values of decolorization efficiency were found to be in good agreement with obtained experimental values (R²=0.9649). The maximum decolorization efficiency was predicted to be 87.19% at an AO7 concentration of 49mg/L, adsorbent dosage of 0.8g/L, reaction time of 27min and initial pH of 6. The results of isotherm study fit the Freundlich model (R²>0.9). Moreover, the adsorption of AO7 onto modified MMT was increased with increasing temperature which could be explained by the endothermic nature of the adsorption process.