Modified nano-γ-alumina with 2, 4-‌dinitrophenyl hydrazine as an efficient adsorbent for the removal of everzol red 3BS dye from aqueous solutions

In the presented study, a new and efficient sorbent for the removal of Everzol Red 3BS dye from aqueous solutions was prepared by immobilization of 2,4­dinitrophenyl hydrazine (DNPH) on γalumina (γAl2O3) ­nanoparticles coated with sodium dodecyl sulfate (DNPH­­­­γalumina). The structure and morphology of the produced sorbents were characterized by Fourier Transform Infrared (FTIR) and Scanning electron microscopy (SEM). Batch studies were performed to study the effect of various experimental parameters such as contact time, initial dye concentration, adsorbent dose and solution pH on the adsorption process. The experimental data were analyzed using the Langmuir and Freundlich isotherm models. The isotherm studies showed that the adsorption experimental data were fitted by Langmuir isotherm model. The maximum monolayer adsorption capacity (qmax) ­obtained from the Langmuir model was 10.21 and 86.96 mg/g for Everzol Red 3BS dye on nanoγalumina and DNPH modified γalumina nanoparticles (DNPH­­­­γalumina), respectively. Meanwhile, thermodynamic parameters such as Gibbs free energy (∆G°), enthalpy (∆H°) and entropy (∆S°) were evaluated. We found out that ∆G°, ∆H°, and ∆S° for nanoγalumina and DNPH modified γalumina nanoparticles (DNPH­­­­γalumina) are 11.07 and 4.84 kJ/mol, 1.40and 3.55 kJ/mol, and 0.037 and 0.025 kJ/molK, respectively. The negative values of Gibbs free energy change (∆G°) ­show that the adsorption was feasible as the spontaneous and positive values of enthalpy change (∆H°) confirm the endothermic adsorption­­. The obtained results indicate that γalumina (γAl2O3) ­nanoparticles modified with 2, 4dinitrophenyl hydrazine (DNPH γalumina) can be used as an efficient adsorbent material for the adsorption of anionic dyes from aqueous solutions.