Pingfang Han

Study on degradation of dimethoate solution in ultrasonic airlift loop reactor

In this work, the degradation of dimethoate solution in ultrasonic airlift loop reactor (UALR) assisted with advanced oxidation processes was studied. The effects of O3 flow rate, ultrasonic intensity, pH value and reaction temperature on the degradation rate were investigated. UALR imposed a synergistic effect combining sonochemical merit with high O3 transfer rate. Under the optimal operation conditions: ultrasonic irradiation time was 4h, O3 flow rate was 0.41 m3h(-1), ultrasonic intensity was 4.64 W cm(-2), pH value was 10.0, reaction temperature was 25 degrees C, and initial concentration of dimethoate was 20 mg L(-1), degradation rate of dimethoate increased to 90.8%. The experimental results indicated that the method of UALR degradation of organic pollutants in the presence of gas could reduce reaction time and improve degradation rate. UALR was an advisable choice for treating organic waste waters and this device could be easily scale up. Thus this process has wide application prospect in industry.

Pretreatment of Crude Oil by Ultrasonic-electric United Desalting and Dewatering

Abstract A technology of ultrasonic-electric united desalting and dewatering of crude oil is studied. The ultrasonic setup is designed to form a standing-wave field, which is more efficient for agglomeration of water particles. The desalting and dewatering results of the ultrasonic-electric united process are compared with those of the electric process. For high salt-contenting crude oil (40-70 mg·L −1 ), the salt content is still above 10.0 mg·L −1 after crude oil has been treated by two-stage electric desalting process in refinery, which cannot meet the need of refinery. Ultrasonic-electric united process is a novel technology for treating the high salt-contenting oil. On the optimal operating conditions of the ultrasonic-electric united process, the salt content of crude oil can be reduced from 67.5 mg·L −1 to 3.97 mg·L −1 by one-stage ultrasonic-electric united process, and the water content falls below 0.3% (by volume). The results show that the ultrasonic-electric united process is more effective than the electric process in high salt-contenting oil desalting. This technology should be useful in the refinery process.

Effect of the Ultrasound Generated by Flat Plate Transducer Cleaning on Polluted Polyvinylidenefluoride Hollow Fiber Ultrafiltration Membrane

Abstract Polyvinylidenefluoride (PVDF) hollow fiber ultrafiltration membrane is frequently employed in water treatment. However, the fouling of ultrafiltration membranes affects the economic effectiveness of such process significantly. The ultrasound generated by flat plate transducer (UFPT) was used to clean the polluted PVDF ultrafiltration membrane with 2 g·L −1 of citric acid aqueous solution in our study. The effects of UFPT intensity on the membrane surface were studied. The new membrane was easy to be polluted by the saturated CaCl 2 solution. A synergistic effect of UFPT and 2 g·L −1 citric acid aqueous solution could remove the foul of the membrane, and its flux could be recovered about 81%. The flux recovery of old membrane polluted was increased to 73.2% after 7 h soaking in citric acid aqueous solution, but its flux recovery without soaking was only increased to 56.2%.

Treatment of Dimethoate Aqueous Solution by Using Ultrasonic Airlift Loop Reactor

Ultrasonic airlift loop reactor (UALR) shows potential and wide application for wastewater treatment. In this paper the performance and efficiency of UALR in dimethoate degradation were presented. The effects of O3 flow rate, ultrasonic intensity and initial concentration of dimethoate on degradation rate were investigated. UALR imposed a synergistic effect combining sonochemical merit with high O3 transfer rate. The results showed that UALR not only increased degradation rate, but also was better than the simple sum of degradation by O3 and ultrasound separately. Under the operation conditions of O3 flow of 0.34m^3•h^(-1), ultrasonic intensity 3.71W•cm^(-2), and initial concentration of dimethoate at 20 mg•L^(-1), the degradation rate of dimethoate increased to 80%. UALR seems an advisable choice for treating organic wastewater and this process may have wide application prospect in industry.