The study first investigated the effects of individual ultrasound and high-speed shearing on emulsification, both obtaining emulsions with average sizes of approximately 1 μm. Subsequently, a combined strategy to utilize shearing instrument producing coarse emulsion for ultrasonic microreactor was proposed. Immiscible liquids were drawn into the stirring chamber by rotating paddles, where they underwent strong shearing and thorough mixing. The pre-mixed liquids were introduced into microchannel and subjected to further processing by oscillating cavitation bubbles. Through optimization of experimental parameters such as residence time and recycle ratio, the average emulsion size was significantly reduced to 522 nm. Finally, a dual-frequency strategy using ultrasound frequencies of 20 and 40 kHz consecutively further reduced the emulsion size to 307 nm. In comparison with conventional sonoreactors and high-pressure homogenizers, this dual-frequency approach demonstrated superior emulsification performance with less surfactant addition and energy input, indicating its high applicability on continuous emulsification process with proper design and optimization.
Dai Hongliang,Lu Xiwu,Peng Yonghong,Yang Zixuan,Zhsssu Huaqing
The HAP crystallization for phosphorus removal from wastewater contributes to an environmental friendly production due to the fact that it helps reduce or eliminate the water eutrophication as well as increases the recovery of mineral resources. However, the generated microcrystalline with poor settleability in high levels of supersaturation solution has a negative effect on the phosphorus recovery efficiency. To overcome the drawback, multiple reagent feed ports (four feed ports) and different recirculation ratio (1.0, 1.5, 2.0, 2.5, 3.0) were investigated to control the levels of supersaturation in an air-agitated reactor with calcite as seeds. Results showed that the approach of multiple reagent feed ports could improve the conversion ratio of orthophosphate, but it had a limited effect (∼3% improvement) on phosphorus recovery efficiency (deposition on the seeds). With the increase of the recirculation ratio, the recovery efficiency was increased gradually and reached an optimal value of 85.63% under the recirculation ratio of 2.5 and four feed ports. This is because the adopted strategies could reduce the level of supersaturation by diluting the concentration of the reagents and inhibit large numbers of microcrystalline coinstantaneous occurrence. Meanwhile, the crystallized products were detected and analyzed by scanning electron micrograph (SEM) with energy-dispersive spectrometry (EDS) and X-ray diffraction (XRD), which were proved to be HAP with a high purity. Collectively, these results demonstrated that supersaturation control using conventional approaches had a limited improvement on the phosphorus recovery efficiency in the form of HAP, and the new control strategies for supersaturation dispersion should be developed in the further study.
危险品化学品经营许可证（带存储）