Water Ultrasonic Degradation Of P-nitrophenol

Ultrasound is a novel wastewater treament method in recent years .It has many advantages in toxic and no biodegradable organic wastewater treament. Therefore p-Nitrophenol (P-NP), a priority toxic pollutant, is chosen as degradation substance to study the sonochemical technology in this paper .A pulsing sonifer with a frequency at 20kHz is used to study the sonochemical technology .The work is divided into two parts:1 . Sonochemical degradation of P-NP in aqueous solution to affect the degradation efficiencySeveral factors are studied in detail, which include the initial concentration ,the initial pH,the energy density,the reaction temperature and the presence of saturated gas.P-NP could be degraded by a pulsing ultrasound with a frequency at 20kHz.The degradation follows a first-order kinetic under the experimental conditions .The first-order rate constant increases with the increase of the initial concentration, because of the gaseous P-NP in the cavitation bubbles. The gaseous P-NP in the cavitation bubbles decrease the cavitation intensity and degradation rate. Because the presence form of P-NP in aqueous solution is changed by the initial pH , the first order rate constant increases with the decrease of the initial pH. Changes of the reaction temperature have almost no effect on the degradation of the P-NP .The degradation effect is improved with the presence of saturated gas during the process of sonochemical degradation .The degradation follows a first-order kinetic, whether the solution is saturated with air.2. Degradation of P-NP in aqueous solution by ultrasound/Fenton reagent processThe degradation of P-NP in water by ultrasound/Fenton reagent process has an obvious synergistic effect .The effects of several factors such as the initial pH , the proportion of initial H2O2 and FeSO4 ,the initial concentration of H2O2 and the reaction temperature .The first order rate constant increases with the decrease of theinitial pH .The appropriate proportion of initial H2O2 and FeSO4 is 10:1 .The degradation efficiency is great enhanced with increasing of the initial concentration of H2O2. Compared with the process without temperature control, the process with temperature control improve the degradation efficiency of the P-NP .The temperature raise gradually, for the pulsing ultrasound is used .So the invalid decomposition of H2O2 decreases.In conclusion, P-NP could be degraded by a power ultrasound, ultrasound/Fenton regent process could decompose P-NP in aqueous solution efficiently and it has a potential to become an industrial technology for wastewater treament..