A detailed investigation of MnO2 nanorods to be grown onto activated carbon. High efficiency towards aqueous methyl orange adsorption/degradation

Abstract

Herein, we report a one-pot wet chemical method adopted to synthesize ad hoc MnO 2 nanoparticles. By varying both the manganese salt precursors (e.g. sulphate or chloride) and the oxidizing agents (e.g. ammonium persulphate, potassium permanganate or potassium bromate), we succeeded in tailoring MnO 2 structural, morphological and surface features. Hence, owing to nanopowders peculiar properties, they were exploited as adsorbents for aqueous Methyl Orange (MO) removal. Particularly, novel MnO 2 nanorods (from manganese sulphate and potassium bromate, namely MS_Br) showed the highest removal efficiency probably due to both its polymorphic composition and its highest percentage of pores with diameter under 20 nm. Then, this powder was grown on Activated Carbon (AC40, sample MS_Br@AC40) pellets to either enhance its adsorption properties or to facilitate the adsorbent removal at the end of the kinetic test. Novel MS_Br@AC40 shows superior MO removal capabilities, achieving the almost total pollutant disappearance, thanks to the synergistic adsorption/oxidation features between carbon (high surface area, i.e. 1200 m 2 g À1) and MnO 2. By means of HPLC-MS on eluates, we also managed to investigate MS_Br and MS_Br@AC40 degradative power towards MO molecules, thus leading to a novel degradation pathway. Finally, the adsorbent regeneration capability has been evaluated, showing very promising results.

The preparation of synthetic graphite materials with hierarchical pores from lignite by one-step impregnation and their characterization as dye absorbents

“…This indicates that ILG-2700 has a better recycling performance and economic value compared with other adsorption materials. [52][53][54][55] The gradual decrease in the adsorption capacity may be due to the fact that methyl orange without desorption occupies the adsorption site; this results in a slight decrease in subsequent adsorption or change in the ILG-2700 structure during desorption and regeneration. Therefore, further studies are required to improve the desorption rate to ensure that the surface of ILG-2700 aer desorption has less residual methyl orange.…”

Single-step synthesis of eucalyptus sawdust magnetic activated carbon and its adsorption behavior for methylene blue

“…10 Compared with other methods of water pollution control, such as coagulation/occulation, advanced oxidation processes, ozonation, membrane ltration and biological treatment, 11 adsorption is considered to be a high efficient, green, low cost and easy to use procedure for the removal of dyes. 12 Activated carbon, as one of the most commonly used adsorbents, could be used to adsorb the organic pigment [13][14][15][16][17][18][19][20] during the treatment of wastewater, as it has rich pore structure and excellent specic surface area.…”

A Novel Au@Cu2O-Ag Ternary Nanocomposite with Highly Efficient Catalytic Performance: Towards Rapid Reduction of Methyl Orange Under Dark Condition

“…For instance, Chen et al prepared layered double hydroxides decorated biomass-derived porous carbons to reduce MO from aqueous solution [12]. Pargoletti et al synthesized activated carbon-based MnO 2 nanoparticles by hydrothermal method and realized the adsorption and degradation of MO [13]. Unfortunately, regeneration difficulties, high cost, high carbon emission, and large losses of carbon source restrict their practical application [9].…”