Mechanistic insight on the sonolytic degradation of phenol at interface and bulk using additives

Abstract

Present work investigated the degradation of phenol based on theoretical knowledge of bubble dynamic and experimental studies. Optimum parameters of theoretical knowledge such as initial concentration of phenol: 1.1 mole/L; concentration of additive: 2 g/L; liquid medium temperature: 35 degrees C and pressure of liquid medium: 101325 Pa were considered for the experimental study. The degradation was further explored in the presence of zinc oxide (effect of particle size), hydrogen peroxide (effect on hydroxyl radical concentration), and sodium chloride (effect of a change in liquid properties) and its effect on degradation of phenol. The degradation of phenol increased in the presence catalyst such as 0.61 +/- 0.013 moles L-1 min(-1) (hydrogen peroxide), 0.44 +/- 0.014 moles L-1 min(-1) (zinc oxide), and 0.5 +/- 0.013 moles L-1 min(-1) (sodium chloride) compare to the absence of catalyst 0.24 +/- 0.009 moles L-1 min(-1). The results confirmed that maximum degradation of phenol obtains in the presence of hydrogen peroxide (cavitational yield: 15.9x10(-5) mg/J, the rate constant: 4.8x10(-5) min(-1), and TOC removal 28.5%). The presence of sodium chloride showed the considerable effect on degradation and TOC removal. Results confirmed that the degradation of phenol is driven by the hydroxyl radicals' mechanism and increased with increase in the concentration of hydroxyl radicals. The degradation of phenol was highly dependent on the concentration of phenol near vicinity of the liquid-bubble interface.