Adsorption of methyl orange on ZnO supported by seawater-modified red mud

Abstract

In this study, a novel adsorbent (SRM-ZnO) was prepared using zinc oxide supported on red mud in a seawater medium and was used for the adsorption of methyl orange (MO). It is expected to solve the recycling of red mud and prepare an economical adsorbent with high efficiency to adsorb dye wastewater. Material composition and morphology analyses showed that hydrotalcite compounds were attached on the surface of SRM-ZnO. The hydrotalcite compounds can increase the surface area of the modified red mud and thus increase the adsorption capacity of MO. The adsorption of MO dye on modified red mud conforms to the Temkin isotherm model and pseudo-second-order kinetic model. The adsorption behavior mainly includes physical interaction, supplemented with chemical interactions. Result also found that the adsorption of MO on SRM-ZnO is a spontaneous exothermic process. HIGHLIGHTS A novel adsorbent was prepared using ZnO supported on red mud in seawater.; Hydrotalcite compounds formed on the surface of SRM-ZnO can improve adsorbing capacity.; The adsorption complies with the Temkin isotherm model and pseudo-second-order kinetic model.; The adsorption is mainly physisorption, supplemented with chemical adsorption.;

Keywords

• adsorption
• methyl orange
• red mud
• seawater
• zinc oxide