No abstract

Mn 3 O 4 −reduced graphene oxide (rGO) hybrids were synthesized, and their catalytic performance in heterogeneous activation of peroxymonosulfate (PMS) to oxidize a target pollutant, Orange II, in aqueous solutions was investigated. The surface morphology and structure of the Mn 3 O 4 −rGO hybrids were characterized by field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), powder X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA). Through an in situ chemical deposition and reduction, Mn 3 O 4 −rGO hybrids with Mn 3 O 4 nanoparticles at an average size of 29.2 nm were produced. The catalytic activity in Orange II oxidative decomposition was evaluated in view of the effects of various processes, pH, PMS concentration, Orange II concentration, and temperature. The combination of Mn 3 O 4 nanoparticles with graphene sheets leads to a much higher catalytic activity than that of pure Mn 3 O 4 or rGO. Graphene was found to play an important role in Mn 3 O 4 dispersion and decomposition of Orange II. Typically, 30 mg/L of Orange II could be completely oxidized in 120 min at 25 °C and 0.05 g/L of Mn 3 O 4 −rGO hybrids, showing a promising application of the catalyst in the oxidative degradation of aqueous organic pollutants. The efficiency of Orange II decomposition increased with increasing temperature (25−55 °C), pH (4.0−11.0), and PMS dosage (0.25−1.5 g/L), but it decreased with increasing initial Orange II concentration (30−90 mg/L). Mn 3 O 4 −rGO hybrids exhibited stable performance without losing activity after four successive runs.

Selective anion extraction is useful for the recovery and purification of valuable chemicals, and in the removal of pollutants from the environment. Here we report that FeII 4L4 cage 1 is able to extract an equimolar amount of ReO4 −, a high‐value anion and a nonradioactive surrogate of TcO4 −, from water into nitromethane. Importantly, the extraction was efficiently performed even in the presence of 10 other common anions in water, highlighting the high selectivity of 1 for ReO4 −. The extracted guest could be released into water as the cage disassembled in ethyl acetate, and then 1 could be recycled by switching the solvent to acetonitrile. The versatile solubility of the cage also enabled complete extraction of ReO4 − (as the tetrabutylammonium salt) from an organic phase into water by using the sulfate salt of 1 as the extractant.

No abstract

No abstract