Spraying Model PAHs on a Charged TiO₂ Surface for High-Efficiency Degradation

Abstract

The degradation of four model PAH compounds was studied by spraying from a micrometer-sized, grounded nozzle a solution of the PAH in a 1:1 solvent of toluene and isopropanol with a trace of water onto wetted TiO 2 anatase nanoparticles, which were immobilized on an etched stainless-steel support charged at +2 kV. Rubrene was chosen because of its established degradation pathways, and 1-methylpyrene, 2-methylnapththalene, and bis(pyren-1-yl)ethane were chosen because of their molecular structure, containing aromatic islands with short aliphatic groups, representative of a thermally and catalytically processed heavy feed stream. The fractional reaction yield was measured using different support materials and by applying different external voltages to the metal substrate. The optimized method yielding 75% degradation was applied to the other three PAHs, resulting in higher-mass degradation products, apparently formed via radical polymerization.

Spontaneous Reduction-Induced Degradation of Viologen Compounds in Water Microdroplets and Its Inhibition by Host–Guest Complexation

“…In addition to the above mechanistic studies, there is also a fast expansion of practical applications of microdroplet chemistry, including green synthesis, − nanomaterial synthesis, bacterial and contaminant treatment, , biochemical reactions, , CO 2 utilization, etc. In this study, we focus on the self-degradation of several highly toxic viologen compounds, including 1,1′-diethyl-4,4′-bipyridinium diiodide (known as ethyl viologen, EV for short), 1,1′-dimethyl-4,4′-bipyridinium dichloride (known as paraquat, PQ for short), and 1,1′-ethylene-2,2′-bipyridinium dibromide (known as diquat, DQ for short), using water microdroplets.…”