Removal of azo dye acid orange 7 through adsorption on unmodified and surface-modified zinc oxide catalysts: equilibrium and kinetic studies

Acid orange 7 (AO7), a non-biodegradable azo dye, has received great attention due to its high consumption rate and extensive release into the environment. The adsorption of AO7 on the commercial (ZnO) and surface fluorinated ZnO (F-ZnO), a novel and low-cost adsorbent, was studied by using adsorption isotherms and kinetic models. Freundlich, Langmuir and Dubinin–Radushkevich (D–R) isotherms were used to evaluate adsorption efficiencies. The experimental results revealed that surface fluorination not only enhanced the hydrophobicity of zinc oxide, but it also distinctly increased the adsorption capacity of catalyst for AO7 by about 4.5 times. The kinetic results showed that the resulting adsorption was very fast and the pseudo-second order model closely fitted the experimental data. The k2 value obtained from the pseudo-second order model was 0.113 (g mg-1 min-1).

کلیدواژه ها:

zinc oxide catalysts ، adsorption ، acid orange 7 ، surface fluorination ، water treatment