Investigations in physical mechanism of the oxidative desulfurization process assisted simultaneously by phase transfer agent and ultrasound

Abstract

This paper attempts to discern the physical mechanism of the oxidative desulfurization process simultaneously assisted by ultrasound and phase transfer agent (PTA). With different experimental protocols, an attempt is made to deduce individual beneficial effects of PTA and ultrasound on the oxidative desulfurization system, and also the synergy between the effects of PTA and ultrasound. Effect of PTA is more marked for mechanically stirred system due to mass transfer limitations, while intense emulsification due to ultrasound helps overcome the mass transfer limitations and reduces the extent of enhancement of oxidation by PTA. Despite application of PTA and ultrasound, the intrinsic factors and properties of the reactants such as polarity (and hence partition coefficient) and diffusivity have a crucial effect on the extent of oxidation. The intrinsic reactivity of the oxidant also plays a vital role, as seen from the extent of oxidation achieved with performic acid and peracetic acid. The interfacial transport of oxidant in the form of oxidant-PTA complex reduces the undesired consumption of oxidant by the reducing species formed during transient cavitation in organic medium, which helps effective utilization of oxidant towards desulfurization.

Ultrasonically treated liquid interfaces for progress in cleaning and separation processes

“…transesterification for the production of biodiesel, hydrolysis for degradation of compounds 85 including polymers, 86 acid or base-catalyzed methanolysis, 87 oxidative desulfurization, 88 demulsification 89 and nanoemulsification, 90 amongst others). transesterification for the production of biodiesel, hydrolysis for degradation of compounds 85 including polymers, 86 acid or base-catalyzed methanolysis, 87 oxidative desulfurization, 88 demulsification 89 and nanoemulsification, 90 amongst others).…”

Mechanistic investigation of Sono–Phosphotungstic acid/phase transfer agent assisted oxidative desulfurization of liquid fuel

“…The experimental protocols with detail experimental summary of the present study are depicted in Table . The optimum values that is volume ratio of organic to aqueous phase and amount of H 2 O 2 was fixed as per our results of previous paper . The experiments were carried out in different oxidants system with combinations of formic acid, acetic acid, and/or phosphotungustic acid are as follows: (a) Acetic acid + H 2 O 2 + TBAB, (b) formic acid + H 2 O 2 + TBAB, (c) Phosphotungustic acid + Formic acid + H 2 O 2 + TBAB.…”

“…Generation of microemulsification through ultrasound enhances the liquid–liquid interfacial area that is important for cavitation of microbubble . In previous papers, it has been reported that ultrasound assisted oxidative desulfurization process can significantly improve the reaction efficiency under phase transfer agents (PTA) . The aim of this study is to investigate the physical and chemical effect of ultrasound on oxidative desulfurization of DBT with coupling of phosphotungstic acid and PTA.…”

Intensification of Wastewater Treatment using Sono-hybrid Processes: An Overview of Mechanistic Synergism

“…If the static pressure is raised above acoustic pressure amplitude and the radial bubble motion transform into stable oscillatory one. In this case, all chemical effects of transient cavitation are eliminated [12,37,38], and the system resembles a mechanically stirred mixed system. It should be noted that the ultrasound wave phenomenon remains unaffected by static pressure.…”