Preparation of MnO2@PP MB for Organic Dyes Removal

Abstract

The removal of organic dyes from wastewater using manganese dioxide (MnO₂) and its composites has garnered significant attention, but recycling them remains challenging. In this study, MnO₂ was combined with polypropylene melt-blown nonwoven material (PP MB) in a simple way to prepare a composite material, which makes MnO₂ easy to be recycled and reused. MnO₂ with sea urchin-like structure were synthesized using a hydrothermal method and subsequently anchored onto the surface of PP MB modified by polydopamine (PDA) in various loading concentration, resulting in the preparation of MnO₂@PP MB for removing organic dyes from wastewater. The size of the synthesized MnO₂ is about 6 μm and its specific surface area is 21.73 m²/g. When the loading concentration of MnO₂ is 1 mg/mL, the pH of adsorption solution is 3, and the adsorption solution temperature is 25 °C, the removal efficiencies of MnO₂-1@PP MB for rhodamine B (RhB), methyl blue (MB), methyl orange (MO), and Carmine (CRM) in water all are achieved 99.00% in an impressive rate. Remarkably, even after undergoing twenty adsorption-desorption cycles, the removal efficiency for of MnO₂-1@PP MB for RhB remained consistently around 99.00%. Furthermore, it was found that the removal behavior of MnO₂@PP MB for RhB follows the pseudo-second-order kinetic model, meaning that is the adsorption process is primarily driven by chemical interactions. Compared to pristine PP MB, the mechanical properties of MnO₂-1@PP MB just slightly decrease.