MnOx-modified ZnAl-LDOs as high-performance adsorbent for the removal of methyl orange

摘要

MnO_x modified ZnAl layered double oxides (M-LDO) nanocomposites were prepared through an intercalation/ reduction/calcination process. The morphology and crystal structure of M-LDO were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), Thermogravimetric analysis(TGA) and Fourier transform infrared spectroscopy (FT-IR) analysis methods. The results confirmed that the manganese oxide nanoparticles were well distributed on the LDO support. Methyl orange (MO) was chosen as a common water-soluble azo dye probe to evaluate the adsorption performance of M-LDO. The effects of MO initial concentration, agitation time, and temperature on MO adsorption were investigated. It was found that adsorption equilibrium data were best represented by the Langmuir and Redlich-Peterson isotherms and the maximum adsorption capacity was 617.28 mg g~(-1) obtained from the Langmuir isotherm, which was much larger than some reported adsorbents. Besides, the adsorption process was spontaneous and endothermic in nature and followed a pseudo-second-order kinetic model. The mechanism of the adsorption process was elaborated by an intraparticle diffusion model. Moreover, the regeneration test of M-LDO was carried out and it showed that the used M-LDO was feasible for at least five times. In principle, this adsorbent with a high adsorption capacity and great reutilization performance could be a very promising adsorbent for wastewater treatment.