Sonochemical degradation of polycyclic aromatic sulfur hydrocarbons (PASHs) in aqueous solutions exemplified by benzothiophene

Abstract

The degradation of polycyclic aromatic sulfur hydrocarbons (PASHs) in aqueous solutions due to sonochemical processes was studied. Benzothiophene (BT), and dibenzothiophene (DBT) in addition to two polycyclic aromatic hydrocarbons, namely phenanthrene (Phe) and naphthalene (Nap) were compared. Results showed that all polycyclic aromatic compounds were decomposed rapidly following a pseudo-first-order kinetics upon ultrasonic irradiation in aqueous solutions. The rate constant increased with increasing pH and decreased with increasing initial benzothiophene concentration. Whereas, for temperature, the rate increased with temperature up to 50°C then decreased upon further increase in temperature above 50°C. Hydroxybenzothiophenes, dihydroxybenzothiophenes, and benzothiophene-dione were identified as major intermediates. Also evolution of carbon dioxide and sulfite was observed. Hydroxyl radicals play the major role in the decomposition of PASHs. The toxicity of sonochemically treated solutions was evaluated by monitoring the respiration rate of E. coli. Results indicate that a sonochemically treated benzothiophene sample improved the respiration rate of E. coli compared to an untreated sample.

Degradation of alachlor in aqueous solution by using hydrodynamic cavitation

“…Consequently the degradation decreases as hydroxyl radicals are scavenged by protons as pH decreases. Similar effects have been observed in photocatalytic degradation of alachlor [28] and sonochemical degradation of polycyclic aromatic sulfur hydrocarbons in aqueous solutions [12].…”

Degradation of rhodamine B in aqueous solution by using swirling jet-induced cavitation combined with H2O2

“…• OH radicals can attack organic pollutants via (a) addition to the aromatic ring or to double bonds, and (b) electron or hydrogen abstraction [8]. Recently, ultrasonic cavitation has been attracting attention as a AOPs for the elimination of the hazardous chemical substances in water [9][10][11][12][13].…”

Generation Mechanism of Hydroxyl Free Radicals in Micro–Nanobubbles Water and Its Prospect in Drinking Water

“…For instance, methyl orange [127], phenol [114], and rhodamine B [117] were best degraded by MNBs under acidic conditions. Nevertheless, the alachlor [118], benzothiophene (BT) [136], and diethyl phthalate [130] degradation by MNBs were successful under alkaline conditions (Figure 4). This is because the pH affects the free radicals generated by MNBs and the physical and chemical properties of the pollutant itself.…”