Removal of Methylene Blue from Aqueous Solution Using a Polarizable Nanolayered Manganese Oxide Film

Abstract

A layered manganese oxide film grown electrochemically was applied to remove methylene blue (MB), a cationic dye, from an aqueous solution. A layered MnOx film intercalated with tetraethylammonium (Et4N) cations was deposited potentiostatically at +1.0 V (vs. Ag/AgCl) from an aqueous Mn 2+ solution containing Et4NCl. Et4N cations were sandwiched between negatively charged MnOx layers. When the Et4N/MnOx film was immersed in a solution containing MB alone, the intercalated Et4N cations were replaced with MB in a solution phase by an ion-exchange mechanism. The uptake capacity of the Et4N/MnOx film for MB was estimated to be 45.3 mg per 1.0 g of MnO2. In the presence of KCl, the MB sorption was seriously restricted because the interlayer space was occupied by K + ions. However, the MnOx film anodized at +0.8 V can selectively take up MB molecules from the KCl solution. This can be ascribed to an increase in the interlayer space available to the sorption of MB due to the extraction of K + ions, where the MnOx surface probably has a specific affinity toward MB molecules.

pH-dependent mechanisms of methylene blue reacting with tunneled manganese oxide pyrolusite

“…The dominated mechanism may depend on the forms of manganese oxide [3]. The MB removal using layered manganese oxides have been widely studied, however, the mechanisms of MB removal using tunneled (molecular sieve) manganese oxides are still unknown [27]. Fig.…”

Electrodeposited CuAgHg Multimetallic Thin Films for Improved CO2 Conversion: the Dramatic Impact of Hg Incorporation on Product Selectivity

“…XPS spectra (Figure ) displayed typical spectral features for Cu, Ag, and Hg, respectively: peaks at binding energies of 932 and 952 eV for Cu 2p (copper metal), at 368 and 374 eV for Ag 3d (silver metal), and the spin–orbit coupled doublet of Hg at 101 and 105 eV (mercury metal) . The multimetallic films exhibited spectral features related to CuO (a satellite peak at 945 eV in XPS spectra and XRD patterns; Figures and S4), − which presumably formed due to air exposure during characterization.…”