Removal of Aqueous Phenol by Adsorption and Oxidation with Doped Hydrophobic Cryptomelane-Type Manganese Oxide (K−OMS-2) Nanofibers

Abstract

Molecular adsorption and oxidation at manganese oxide/liquid interfaces has attracted increased interest due to its importance in the development of heterogeneous catalysts, microbial fuel cells, and selective adsorption materials. Here we report the adsorption and oxidation of phenolic compounds on Cu2+, Co3+, and Ce4+ doped K−OMS-2 nanofibers. Different metal ion doped K−OMS-2 catalysts show distinct adsorption and oxidation ability. The structure and compositions of doped K−OMS-2 catalysts were characterized by X-ray diffraction and atomic absorption analyses. The relationships of catalyst structure-catalytic properties were discussed. The adsorbed polymeric nanospheres on doped K−OMS-2 nanofibers were investigated by field emission scanning electron microscopy, Fourier transform infared spectroscopy, transmission electron microscopy, and energy dispersive X-ray analyses. These nanospheres were totally oxidized to CO2 in oxygen or air at 553−603 K catalyzed by doped and undoped K−OMS-2 itself. OMS-2 was regenerated with air or oxygen. The chemisorption and oxidation of phenol in an anaerobic environment (N2) demonstrate that lattice oxygen of cryptomelane is involved in these processes. Free-radical mechanisms are proposed for the oxidation of phenol in O2 and for the formation of phenolic nanospheres. Compared with undoped K−OMS-2, metal ion doped K−OMS-2 shows higher adsorption capacity of phenolic compounds and higher phenol removal rate.

Gas phase Catalytic Oxidation of VOCS using Hydrothermally Synthesized Nest-like K-OMS 2 Catalyst

“…The BET surface area of K-OMS 2 catalyst obtained was found to be 49.97 m 2 g -1 . This is consistent with that obtained from other studies (Jothiramalingam et al 2006;Hu et al 2010) but is lower than the surface area of K-OMS 2 catalyst produced in our previous study which is 76.72 m 2 g -1 (Yodsa-nga et al 2015), in which K-OMS 2 catalyst was prepared at aging temperature and time of about 75ºC and 21 h, respectively.…”

Nanofiber-Based Materials for Persistent Organic Pollutants in Water Remediation by Adsorption

“…For instance, temperature was shown to act as a catalyst for phenol adsorption on doped cryptomelane manganese nanofibers, with faster metal oxide surface hydroxylation reported for temperatures from 140 • C (Table 7, N19). The created surface hydroxyl groups can bind to phenol and form phenolic complexes, thus enhancing the adsorption capacity even for a relatively low specific surface area of 40 m 2 /g, impeded by the higher density of metals compared to carbon atoms [47].…”

K0.25Mn2O4nanofiber microclusters as high power cathode materials for rechargeable lithium batteries

“…[32][33][34][35][36] Single-crystalline K 0.25 Mn 2 O 4 could be suitable as a cathode material for lithium ion batteries because its potassium ions can not only maintain the structure, but also increase the ion diffusion rate. [26][27][28][29][30] Solution B was prepared by dissolving 1.5 g of oxone in 10 mL of double de-ionized water.…”