Enhanced degradation of 2,4-dichlorophenol by ultrasound in a new Fenton like system (Fe/EDTA) at ambient circumstance

This study investigated the effect of ultrasound (US) enhancement on the degradation of 2,4-DCP in a new Fenton like system. An obviously synergistic effect was observed after introduction of US into the Fe/EDTA system. Good correspondences with pseudo-first-order kinetic were found in each reaction system. It was demonstrated that the degradation rate constant (k_obs) of DCP in US/Fe/EDTA was 7 and 32 times higher than those in Fe/EDTA and US system alone. Simultaneously, lower first-order k_obs was also obtained in the investigation of decomposition of EDTA. At 60 min reaction time, Removals of 81% TOC, complete DCP and 89% EDTA were achieved. Low molecular weight organic acids are identified as the main products, which contribute to the solution self-buffer at about pH 6.5 along with the reaction. In addition, the effect of initials condition, i.e., iron addition, EDTA dosage, DCP concentration and US input power as well as reaction temperature were studied and reaction activation energy (E_a) was also calculated.     

Direct comparison of the reactivity of the non-oxidic phase of Ru(0 0 0 1) and the RuO2 phase in the CO oxidation reaction

Applying in situ surface X-ray diffraction (SXRD) together with on-line mass spectrometry during the CO oxidation over Ru(0 0 0 1) allows a direct comparison of the reactivity of the non-oxidic state with that of the RuO₂(1 1 0) covered surface. This comparison reveals that the RuO₂(1 1 0) surface is a catalytically active phase at least as active as the non-oxidic phase. At high CO and O₂ pressures of 200 mbar and temperatures above 550 K, the CO oxidation reaction does not proceed isothermally on the RuO₂(1 1 0) surface. The released reaction heat leads rather to an increase of the sample temperature of up to 130 K accompanied by a self-acceleration of the CO oxidation reaction.